Tag Archives: data

Protecting Personal Data in Grab’s Imagery

Post Syndicated from Grab Tech original https://engineering.grab.com/protecting-personal-data-in-grabs-imagery

Image Collection Using KartaView

Starting a few years ago, we realised the strong demand to better understand the streets where our drivers and clients go, with the purpose to better fulfil their needs and also to be able to quickly adapt ourselves to the rapidly changing environment in the Southeast Asia cities.

One way to fulfil that demand was to create an image collection platform named KartaView which is Grab Geo’s platform for geotagged imagery. It empowers collection, indexing, storage, retrieval of imagery, and map data extraction.

KartaView is a public, partially open-sourced product, used both internally and externally by the OpenStreetMap community and other users. As of 2021, KartaView has public imagery in over 100 countries with various coverage degrees, and 60+ cities of Southeast Asia. Check it out at www.kartaview.com.

Figure 1 - KartaView platform
Figure 1 – KartaView platform

Why Image Blurring is Important

Many incidental people and licence plates are in the collected images, whose privacy is a serious concern. We deeply respect all of them and consequently, we are using image obfuscation as the most effective anonymisation method for ensuring privacy protection.

Because manually annotating the regions in the picture where faces and licence plates are located is impractical, this problem should be solved using machine learning and engineering techniques. Hence we detect and blur all faces and licence plates which could be considered as personal data.

Figure 2 - Sample blurred picture
Figure 2 – Sample blurred picture

In our case, we have a wide range of picture types: regular planar, very wide and 360 pictures in equirectangular format collected with 360 cameras. Also, because we are collecting imagery globally, the vehicle types, licence plates, and human environments are quite diverse in appearance, and are not handled well by off-the-shelf blurring software. So we built our own custom blurring solution which yielded higher accuracy and better cost-efficiency overall with respect to blurring of personal data.

Figure 3 - Example of equirectangular image where personal data has to be blurred
Figure 3 – Example of equirectangular image where personal data has to be blurred

Behind the scenes, in KartaView, there are a set of cool services which are able to derive useful information from the pictures like image quality, traffic signs, roads, etc. A big part of them are using deep learning algorithms which potentially can be negatively affected by running them over blurred pictures. In fact, based on the assessment we have done so far, the impact is extremely low, similar to the one reported in a well known study of face obfuscation in ImageNet [9].

Outline of Grab’s Blurring Process

Roughly, the processing steps are the following:

  1. Transform each picture into a set of planar images. In this way, we further process all pictures, whatever the format they had, in the same way.
  2. Use an object detector able to detect all faces and licence plates in a planar image having a standard field of view.
  3. Transform the coordinates of the detected regions into original coordinates and blur those regions.
Figure 4 - Picture’s processing steps [8]
Figure 4 – Picture’s processing steps [8]

In the following section, we are going to describe in detail the interesting aspects of the second step, sharing the challenges and how we were solving them. Let’s start with the first and most important part, the dataset.

Dataset

Our current dataset consists of images from a wide range of cameras, including normal perspective cameras from mobile phones, wide field of view cameras and also 360 degree cameras.

It is the result of a series of data collections contributed by Grab’s data tagging teams, which may contain 2 classes of dataset that are of interest for us: FACE and LICENSE_PLATE.

The data was collected using Grab internal tools, stored in queryable databases, making it a system that gives the possibility to revisit the data and correct it if necessary, but also making it possible for data engineers to select and filter the data of interest.

Dataset Evolution

Each iteration of the dataset was made to address certain issues discovered while having models used in a production environment and observing situations where the model lacked in performance.

Dataset v1 Dataset v2 Dataset v3
Nr. images 15226 17636 30538
Nr. of labels 64119 86676 242534

If the first version was basic, containing a rough tagging strategy we quickly noticed that it was not detecting some special situations that appeared due to the pandemic situation: people wearing masks.

This led to another round of data annotation to include those scenarios.
The third iteration addressed a broader range of issues:

  • Small regions of interest (objects far away from the camera)
  • Objects in very dark backgrounds
  • Rotated objects or even upside down
  • Variation of the licence plate design due to images from different countries and regions
  • People wearing masks
  • Faces in the mirror – see below the mirror of the motorcycle
  • But the main reason was because of a scenario where the recording, at the start or end (but not only), had close-ups of the operator who was checking the camera. This led to images with large regions of interest containing the camera operator’s face – too large to be detected by the model.

An investigation in the dataset structure, by splitting the data into bins based on the bbox sizes (in pixels), made something clear: the dataset was unbalanced.

We made bins for tag sizes with a stride of 100 pixels and went up to the max present in the dataset which accounted for 1 sample of size 2000 pixels. The majority of the labels were small in size and the higher we would go with the size, the less tags we would have. This made it clear that we would need more targeted annotations for our dataset to try to balance it.

All these scenarios required the tagging team to revisit the data multiple times and also change the tagging strategy by including more tags that were considered at a certain limit. It also required them to pay more attention to small details that may have been missed in a previous iteration.

Data Splitting

To better understand the strategy chosen for splitting the data we need to also understand the source of the data. The images come from different devices that are used in different geo locations (different countries) and are from a continuous trip recording. The annotation team used an internal tool to visualise the trips image by image and mark the faces and licence plates present in them. We would then have access to all those images and their respective metadata.

The chosen ratios for splitting are:

  • Train 70%
  • Validation 10%
  • Test 20%
Number of train images 12733
Number of validation images 1682
Number of test images 3221
Number of labeled classes in train set 60630
Number of labeled classes in validation set 7658
Number of of labeled classes in test set 18388

The split is not so trivial as we have some requirements and need to complete some conditions:

  • An image can have multiple tags from one or both classes but must belong to just one subset.
  • The tags should be split as close as possible to the desired ratios.
  • As different images can belong to the same trip in a close geographical relation we need to force them in the same subset, thus avoiding similar tags in train and test subsets, resulting in incorrect evaluations.

Data Augmentation

The application of data augmentation plays a crucial role while training the machine learning model. There are mainly three ways in which data augmentation techniques can be applied. They are:

  1. Offline data augmentation – enriching a dataset by physically multiplying some of its images and applying modifications to them.
  2. Online data augmentation – on the fly modifications of the image during train time with configurable probability for each modification.
  3. Combination of both offline and online data augmentation.

In our case, we are using the third option which is the combination of both.

The first method that contributes to offline augmentation is a method called image view splitting. This is necessary for us due to different image types: perspective camera images, wide field of view images, 360 degree images in equirectangular format. All these formats and field of views with their respective distortions would complicate the data and make it hard for the model to generalise it and also handle different image types that could be added in the future.

For this we defined the concept of image views which are an extracted portion (view) of an image with some predefined properties. For example, the perspective projection of 75 by 75 degrees field of view patches from the original image.

Here we can see a perspective camera image and the image views generated from it:

Figure 5 - Original image
Figure 5 – Original image
Figure 6 - Two image views generated
Figure 6 – Two image views generated

The important thing here is that each generated view is an image on its own with the associated tags. They also have an overlapping area so we have a possibility to contain the same tag in two views but from different perspectives. This brings us to an indirect outcome of the first offline augmentation.

The second method for offline augmentation is the oversampling of some of the images (views). As mentioned above, we faced the problem of an unbalanced dataset, specifically we were missing tags that occupied high regions of the image, and even though our tagging teams tried to annotate as many as they could find, these were still scarce.

As our object detection model is an anchor-based detector, we did not even have enough of them to generate the anchor boxes correctly. This could be clearly seen in the accuracy of the previous trained models, as they were performing poorly on bins of big sizes.

By randomly oversampling images that contained big tags, up to a minimum required number, we managed to have better anchors and increase the recall for those scenarios. As described below, the chosen object detector for blurring was YOLOv4 which offers a large variety of online augmentations. The online augmentations used are saturation, exposure, hue, flip and mosaic.

Model

As of summer of 2021, the “to go” solution for object detection in images are convolutional neural networks (CNN), being a mature solution able to fulfil the needs efficiently.

Architecture

Most CNN based object detectors have three main parts: Backbone, Neck and (Dense or Sparse Prediction) Heads. From the input image, the backbone extracts features which can be combined in the neck part to be used by the prediction heads to predict object bounding-boxes and their labels.

Figure 7 - Anatomy of one and two-stage object detectors [1]
Figure 7 – Anatomy of one and two-stage object detectors [1]

The backbone is usually a CNN classification network pretrained on some dataset, like ImageNet-1K. The neck combines features from different layers in order to produce rich representations for both large and small objects. Since the objects to be detected have varying sizes, the topmost features are too coarse to represent smaller objects, so the first CNN based object detectors were fairly weak in detecting small sized objects. The multi-scale, pyramid hierarchy is inherent to CNNs so [2] introduced the Feature Pyramid Network which at marginal costs combines features from multiple scales and makes predictions on them. This or improved variants of this technique is used by most detectors nowadays. The head part does the predictions for bounding boxes and their labels.

YOLO is part of the anchor-based one-stage object detectors family being developed originally in Darknet, an open source neural network framework written in C and CUDA. Back in 2015 it was the first end-to-end differentiable network of this kind that offered a joint learning of object bounding boxes and their labels.

One reason for the big success of newer YOLO versions is that the authors carefully merged new ideas into one architecture, the overall speed of the model being always the north star.

YOLOv4 introduces several changes to its v3 predecessor:

  • Backbone – CSPDarknet53: YOLOv3 Darknet53 backbone was modified to use Cross Stage Partial Network (CSPNet [5]) strategy, which aims to achieve richer gradient combinations by letting the gradient flow propagate through different network paths.
  • Multiple configurable augmentation and loss function types, so called “Bag of freebies”, which by changing the training strategy can yield higher accuracy without impacting the inference time.
  • Configurable necks and different activation functions, they call “Bag of specials”.

Insights

For this task, we found that YOLOv4 gave a good compromise between speed and accuracy as it has doubled the speed of a more accurate two-stage detector while maintaining a very good overall precision/recall. For blurring, the main metric for model selection was the overall recall, while precision and intersection over union (IoU) of the predicted box comes second as we want to catch all personal data even if some are wrong. Having a multitude of possibilities to configure the detector architecture and train it on our own dataset we conducted several experiments with different configurations for backbones, necks, augmentations and loss functions to come up with our current solution.

We faced challenges in training a good model as the dataset posed a large object/box-level scale imbalance, small objects being over-represented in the dataset. As described in [3] and [4], this affects the scales of the estimated regions and the overall detection performance. In [3] several solutions are proposed for this out of which the SPP [6] blocks and PANet [7] neck used in YOLOv4 together with heavy offline data augmentation increased the performance of the actual model in comparison to the former ones.

As we have evaluated the model; it still has some issues:

  • Occlusion of the object, either by the camera view, head accessories or other elements:

These cases would need extra annotation in the dataset, just like the faces or licence plates that are really close to the camera and occupy a large region of interest in the image.

  • As we have a limited number of annotations of close objects to the camera view, the model has incorrectly learnt this, sometimes producing false positives in these situations:

Again, one solution for this would be to include more of these scenarios in the dataset.

What’s Next?

Grab spends a lot of effort ensuring privacy protection for its users so we are always looking for ways to further improve our related models and processes.

As far as efficiency is concerned, there are multiple directions to consider for both the dataset and the model. There are two main factors that drive the costs and the quality: further development of the dataset for additional edge cases (e.g. more training data of people wearing masks) and the operational costs of the model.

As the vast majority of current models require a fully labelled dataset, this puts a large work effort on the Data Entry team before creating a new model. Our dataset increased 4x for it’s third version, still there is room for improvement as described in the Dataset section.

As Grab extends its operation in more cities, new data is collected that has to be processed, this puts an increased focus on running detection models more efficiently.

Directions to pursue to increase our efficiency could be the following:

  • As plenty of unlabelled data is available from imagery collection, a natural direction to explore is self-supervised visual representation learning techniques to derive a general vision backbone with superior transferring performance for our subsequent tasks as detection, classification.
  • Experiment with optimisation techniques like pruning and quantisation to get a faster model without sacrificing too much on accuracy.
  • Explore new architectures: YOLOv5, EfficientDet or Swin-Transformer for Object Detection.
  • Introduce semi-supervised learning techniques to improve our model performance on the long tail of the data.

References

  1. Alexey Bochkovskiy et al.. YOLOv4: Optimal Speed and Accuracy of Object Detection. arXiv:2004.10934v1
  2. Tsung-Yi Lin et al. Feature Pyramid Networks for Object Detection. arXiv:1612.03144v2
  3. Kemal Oksuz et al.. Imbalance Problems in Object Detection: A Review. arXiv:1909.00169v3
  4. Bharat Singh, Larry S. Davis. An Analysis of Scale Invariance in Object Detection – SNIP. arXiv:1711.08189v2
  5. Chien-Yao Wang et al. CSPNet: A New Backbone that can Enhance Learning Capability of CNN. arXiv:1911.11929v1
  6. Kaiming He et al. Spatial Pyramid Pooling in Deep Convolutional Networks for Visual Recognition. arXiv:1406.4729v4
  7. Shu Liu et al. Path Aggregation Network for Instance Segmentation. arXiv:1803.01534v4
  8. http://blog.nitishmutha.com/equirectangular/360degree/2017/06/12/How-to-project-Equirectangular-image-to-rectilinear-view.html
  9. Kaiyu Yang et al. Study of Face Obfuscation in ImageNet: arxiv.org/abs/2103.06191
  10. Zhenda Xie et al. Self-Supervised Learning with Swin Transformers. arXiv:2105.04553v2

Join Us

Grab is the leading superapp platform in Southeast Asia, providing everyday services that matter to consumers. More than just a ride-hailing and food delivery app, Grab offers a wide range of on-demand services in the region, including mobility, food, package and grocery delivery services, mobile payments, and financial services across 428 cities in eight countries.

Powered by technology and driven by heart, our mission is to drive Southeast Asia forward by creating economic empowerment for everyone. If this mission speaks to you, join our team today!

Processing ETL tasks with Ratchet

Post Syndicated from Grab Tech original https://engineering.grab.com/processing-etl-tasks-with-ratchet

Overview

At Grab, the Lending team is focused towards building products that help finance various segments of users, such as Passengers, Drivers, or Merchants, based on their needs. The team builds products that enable users to avail funds in a seamless and hassle-free way. In order to achieve this, multiple lending microservices continuously interact with each other. Each microservice handles different responsibilities, such as providing offers, storing user information, disbursing availed amounts to a user’s account, and many more.

In this tech blog, we will discuss what Data and Extract, Transform and Load (ETL) pipelines are and how they are used for processing multiple tasks in the Lending Team at Grab. We will also discuss Ratchet, which is a Go library, that helps us in building data pipelines and handling ETL tasks. Let’s start by covering the basis of Data and ETL pipelines.

What is a Data Pipeline?

A Data pipeline is used to describe a system or a process that moves data from one platform to another. In between platforms, data passes through multiple steps based on defined requirements, where it may be subjected to some kind of modification. All the steps in a Data pipeline are automated, and the output from one step acts as an input for the next step.

Data Pipeline
Data Pipeline (Source: Hazelcast)

What is an ETL Pipeline?

An ETL pipeline is a type of Data pipeline that consists of 3 major steps, namely extraction of data from a source, transformation of that data into the desired format, and finally loading the transformed data to the destination. The destination is also known as the sink.

Extract-Transform-Load
Extract-Transform-Load (Source: TatvaSoft)

The combination of steps in an ETL pipeline provides functions to assure that the business requirements of the application are achieved.

Let’s briefly look at each of the steps involved in the ETL pipeline.

Data Extraction

Data extraction is used to fetch data from one or multiple sources with ease. The source of data can vary based on the requirement. Some of the commonly used data sources are:

  • Database
  • Web-based storage (S3, Google cloud, etc)
  • Files
  • User Feeds, CRM, etc.

The data format can also vary from one use case to another. Some of the most commonly used data formats are:

  • SQL
  • CSV
  • JSON
  • XML

Once data is extracted in the desired format, it is ready to be fed to the transformation step.

Data Transformation

Data transformation involves applying a set of rules and techniques to convert the extracted data into a more meaningful and structured format for use. The extracted data may not always be ready to use. In order to transform the data, one of the following techniques may be used:

  1. Filtering out unnecessary data.
  2. Preprocessing and cleaning of data.
  3. Performing validations on data.
  4. Deriving a new set of data from the existing one.
  5. Aggregating data from multiple sources into a single uniformly structured format.

Data Loading

The final step of an ETL pipeline involves moving the transformed data to a sink where it can be accessed for its use. Based on requirements, a sink can be one of the following:

  1. Database
  2. File
  3. Web-based storage (S3, Google cloud, etc)

An ETL pipeline may or may not have a loadstep based on its requirements. When the transformed data needs to be stored for further use, the loadstep is used to move the transformed data to the storage of choice. However, in some cases, the transformed data may not be needed for any further use and thus, the loadstep can be skipped.

Now that you understand the basics, let’s go over how we, in the Grab Lending team, use an ETL pipeline.

Why Use Ratchet?

At Grab, we use Golang for most of our backend services. Due to Golang’s simplicity, execution speed, and concurrency support, it is a great choice for building data pipeline systems to perform custom ETL tasks.

Given that Ratchet is also written in Go, it allows us to easily build custom data pipelines.

Go channels are connecting each stage of processing, so the syntax for sending data is intuitive for anyone familiar with Go. All data being sent and received is in JSON, providing a nice balance of flexibility and consistency.

Utilising Ratchet for ETL Tasks

We use Ratchet for multiple ETL tasks like batch processing, restructuring and rescheduling of loans, creating user profiles, and so on. One of the backend services, named Azkaban, is responsible for handling various ETL tasks.

Ratchet uses Data Processors for building a pipeline consisting of multiple stages. Data Processors each run in their own goroutine so all of the data is processed concurrently. Data Processors are organised into stages, and those stages are run within a pipeline. For building an ETL pipeline, each of the three steps (Extract, Transform and Load) use a Data Processor for implementation. Ratchet provides a set of built-in, useful Data Processors, while also providing an interface to implement your own. Usually, the transform stage uses a Custom Data Processor.

Data Processors in Ratchet
Data Processors in Ratchet (Source: Github)

Let’s take a look at one of these tasks to understand how we utilise Ratchet for processing an ETL task.

Whitelisting Merchants Through ETL Pipelines

Whitelisting essentially means making the product available to the user by mapping an offer to the user ID. If a merchant in Thailand receives an option to opt for Cash Loan, it is done by whitelisting that merchant. In order to whitelist our merchants, our Operations team uses an internal portal to upload a CSV file with the user IDs of the merchants and other required information. This CSV file is generated by our internal Data and Risk team and handed over to the Operations team. Once the CSV file is uploaded, the user IDs present in the file are whitelisted within minutes. However, a lot of work goes in the background to make this possible.

Data Extraction

Once the Operations team uploads the CSV containing a list of merchant users to be whitelisted, the file is stored in S3 and an entry is created on the Azkaban service with the document ID of the uploaded file.

File upload by Operations team
File upload by Operations team

The data extraction step makes use of a Custom CSV Data Processor that uses the document ID to first create a PreSignedUrl and then uses it to fetch the data from S3. The data extracted is in bytes and we use commas as the delimiter to format the CSV data.

Data Transformation

In order to transform the data, we define a Custom Data Processor that we call a Transformer for each ETL pipeline. Transformers are responsible for applying all necessary transformations to the data before it is ready for loading. The transformations applied in the merchant whitelisting transformers are:

  1. Convert data from bytes to struct.
  2. Check for presence of all mandatory fields in the received data.
  3. Perform validation on the data received.
  4. Make API calls to external microservices for whitelisting the merchant.

As mentioned earlier, the CSV file is uploaded manually by the Operations team. Since this is a manual process, it is prone to human errors. Validation of data in the data transformation step helps avoid these errors and not propagate them further up the pipeline. Since CSV data consists of multiple rows, each row passes through all the steps mentioned above.

Data Loading

Whenever the merchants are whitelisted, we don’t need to store the transformed data. As a result, we don’t have a loadstep for this ETL task, so we just use an Empty Data Processor. However, this is just one of many use cases that we have. In cases where the transformed data needs to be stored for further use, the loadstep will have a Custom Data Processor, which will be responsible for storing the data.

Connecting All Stages

After defining our Data Processors for each of the steps in the ETL pipeline, the final piece is to connect all the stages together. As stated earlier, the ETL tasks have different ETL pipelines and each ETL pipeline consists of 3 stages defined by their Data Processors.

In order to connect these 3 stages, we define a Job Processor for each ETL pipeline. A Job Processor represents the entire ETL pipeline and encompasses Data Processors for each of the 3 stages. Each Job Processor implements the following methods:

  1. SetSource: Assigns the Data Processor for the Extraction stage.
  2. SetTransformer: Assigns the Data Processor for the Transformation stage.
  3. SetDestination: Assigns the Data Processor for the Load stage.
  4. Execute: Runs the ETL pipeline.
Job processors containing Data Processor for each stage in ETL
Job processors containing Data Processor for each stage in ETL

When the Azkaban service is initialised, we run the SetSource(), SetTransformer() and SetDestination() methods for each of the Job Processors defined. When an ETL task is triggered, the Execute() method of the corresponding Job Processor is run. This triggers the ETL pipeline and gradually runs the 3 stages of ETL pipeline. For each stage, the Data Processor assigned during initialisation is executed.

Conclusion

ETL pipelines help us in streamlining various tasks in our team. As showcased through the example in the above section, an ETL pipeline breaks a task into multiple stages and divides the responsibilities across these stages.

In cases where a task fails in the middle of the process, ETL pipelines help us determine the cause of the failure quickly and accurately. With ETL pipelines, we have reduced the manual effort required for validating data at each step and avoiding propagation of errors towards the end of the pipeline.

Through the use of ETL pipelines and schedulers, we at Lending have been able to automate the entire pipeline for many tasks to run at scheduled intervals without any manual effort involved at all. This has helped us tremendously in reducing human errors, increasing the throughput of the system and making the backend flow more reliable. As we continue to automate more and more of our tasks that have tightly defined stages, we foresee a growth in our ETL pipelines usage.

References

https://www.alooma.com/blog/what-is-a-data-pipeline

http://rkulla.blogspot.com/2016/01/data-pipeline-and-etl-tasks-in-go-using

https://medium.com/swlh/etl-pipeline-and-data-pipeline-comparison-bf89fa240ce9

Join Us

Grab is the leading superapp platform in Southeast Asia, providing everyday services that matter to consumers. More than just a ride-hailing and food delivery app, Grab offers a wide range of on-demand services in the region, including mobility, food, package and grocery delivery services, mobile payments, and financial services across 428 cities in eight countries.

Powered by technology and driven by heart, our mission is to drive Southeast Asia forward by creating economic empowerment for everyone. If this mission speaks to you, join our team today!

Data Engineers of Netflix — Interview with Kevin Wylie

Post Syndicated from Netflix Technology Blog original https://netflixtechblog.com/data-engineers-of-netflix-interview-with-kevin-wylie-7fb9113a01ea

Data Engineers of Netflix — Interview with Kevin Wylie

This post is part of our “Data Engineers of Netflix” series, where our very own data engineers talk about their journeys to Data Engineering @ Netflix.

Kevin Wylie is a Data Engineer on the Content Data Science and Engineering team. In this post, Kevin talks about his extensive experience in content analytics at Netflix since joining more than 10 years ago.

Kevin grew up in the Washington, DC area, and received his undergraduate degree in Mathematics from Virginia Tech. Before joining Netflix, he worked at MySpace, helping implement page categorization, pathing analysis, sessionization, and more. In his free time he enjoys gardening and playing sports with his 4 kids.

His favorite TV shows: Ozark, Breaking Bad, Black Mirror, Barry, and Chernobyl

Since I joined Netflix back in 2011, my favorite project has been designing and building the first version of our entertainment knowledge graph. The knowledge graph enabled us to better understand the trends of movies, TV shows, talent, and books. Building the knowledge graph offered many interesting technical challenges such as entity resolution (e.g., are these two movie names in different languages really the same?), and distributed graph algorithms in Spark. After we launched the product, analysts and scientists began surfacing new insights that were previously hidden behind difficult-to-use data. The combination of overcoming technical hurdles and creating new opportunities for analysis was rewarding.

Kevin, what drew you to data engineering?

I stumbled into data engineering rather than making an intentional career move into the field. I started my career as an application developer with basic familiarity with SQL. I was later hired into my first purely data gig where I was able to deepen my knowledge of big data. After that, I joined MySpace back at its peak as a data engineer and got my first taste of data warehousing at internet-scale.

What keeps me engaged and enjoying data engineering is giving super-suits and adrenaline shots to analytics engineers and data scientists.

When I make something complex seem simple, or create a clean environment for my stakeholders to explore, research and test, I empower them to do more impactful business-facing work. I like that data engineering isn’t in the limelight, but instead can help create economies of scale for downstream analytics professionals.

What drew you to Netflix?

My wife came across the Netflix job posting in her effort to keep us in Los Angeles near her twin sister’s family. As a big data engineer, I found that there was an enormous amount of opportunity in the Bay Area, but opportunities were more limited in LA where we were based at the time. So the chance to work at Netflix was exciting because it allowed me to live closer to family, but also provided the kind of data scale that was most common for Bay Area companies.

The company was intriguing to begin with, but I knew nothing of the talent, culture, or leadership’s vision. I had been a happy subscriber of Netflix’s DVD-rental program (no late fees!) for years.

After interviewing, it became clear to me that this company culture was different than any I had experienced.

I was especially intrigued by the trust they put in each employee. Speaking with fellow employees allowed me to get a sense for the kinds of people Netflix hires. The interview panel’s humility, curiosity and business acumen was quite impressive and inspired me to join them.

I was also excited by the prospect of doing analytics on movies and TV shows, which was something I enjoyed exploring outside of work. It seemed fortuitous that the area of analytics that I’d be working in would align so well with my hobbies and interests!

Kevin, you’ve been at Netflix for over 10 years now, which is pretty incredible. Over the course of your time here, how has your role evolved?

When I joined Netflix back in 2011, our content analytics team was just 3 people. We had a small office in Los Angeles focused on content, and significantly more employees at the headquarters in Los Gatos. The company was primarily thought of as a tech company.

At the time, the data engineering team mainly used a data warehouse ETL tool called Ab Initio, and an MPP (Massively Parallel Processing) database for warehousing. Both were appliances located in our own data center. Hadoop was being lightly tested, but only in a few high-scale areas.

Fast forward 10 years, and Netflix is now the leading streaming entertainment service — serving members in over 190 countries. In the data engineering space, very little of the same technology remains. Our data centers are retired, Hadoop has been replaced by Spark, Ab Initio and our MPP database no longer fits our big data ecosystem.

In addition to the company and tech shifting, my role has evolved quite a bit as our company has grown. When we were a smaller company, the ability to span multiple functions was valued for agility and speed of delivery. The sooner we could ingest new data and create dashboards and reports for non-technical users to explore and analyze, the sooner we could deliver results. But now, we have a much more mature business, and many more analytics stakeholders that we serve.

For a few years, I was in a management role, leading a great team of people with diverse backgrounds and skill sets. However, I missed creating data products with my own hands so I wanted to step back into a hands-on engineering role. My boss was gracious enough to let me make this change and focus on impacting the business as an individual contributor.

As I think about my future at Netflix, what motivates me is largely the same as what I’ve always been passionate about. I want to make the lives of data consumers easier and to enable them to be more impactful. As the company scales and as we continue to invest in storytelling, the opportunity grows for me to influence these decisions through better access to information and insights. The biggest impact I can make as a data engineer is creating economies of scale by producing data products that will serve a diverse set of use cases and stakeholders.

If I can build beautifully simple data products for analytics engineers, data scientists, and analysts, we can all get better at Netflix’s goal: entertaining the world.

Learning more

Interested in learning more about data roles at Netflix? You’re in the right place! Keep an eye out for our open roles in Data Science and Engineering by visiting our jobs site here. Our culture is key to our impact and growth: read about it here. To learn more about our Data Engineers, check out our chats with Dhevi Rajendran and Samuel Setegne.

Data Engineers of Netflix — Interview with Kevin Wylie was originally published in Netflix TechBlog on Medium, where people are continuing the conversation by highlighting and responding to this story.

The UEFA EURO 2020 final as seen online by Cloudflare Radar

Post Syndicated from John Graham-Cumming original https://blog.cloudflare.com/the-uefa-euro-2020-final-as-seen-online-by-cloudflare-radar/

The UEFA EURO 2020 final as seen online by Cloudflare Radar

Last night’s Italy-England match was a nail-biter. 1-1 at full time, 1-1 at the end of extra time, and then an amazing penalty shootout with incredible goalkeeping by Pickford and Donnarumma.

Cloudflare has been publishing statistics about all the teams involved in EURO 2020 and traffic to betting websites, sports newspapers, streaming services and sponsors. Here’s a quick look at some specific highlights from England’s and Italy’s EURO 2020.

Two interesting peaks show up in UK visits to sports newspapers: the day after England-Germany and today after England’s defeat. Looks like fans are hungry for analysis and news beyond the goals. You can see all the data on the dedicated England EURO 2020 page on Cloudflare Radar.

The UEFA EURO 2020 final as seen online by Cloudflare Radar

But it was a quiet morning for the websites of the England team’s sponsors.

The UEFA EURO 2020 final as seen online by Cloudflare Radar

Turning to the winners, we can see that Italian readers are even more interested in knowing more about their team’s success.

The UEFA EURO 2020 final as seen online by Cloudflare Radar

And this enthusiasm spills over into visits to the Italian team’s sponsors.

The UEFA EURO 2020 final as seen online by Cloudflare Radar

You can follow along on the dedicated Cloudflare Radar page for Italy in EURO 2020.

Visit Cloudflare Radar for information on global Internet trends, trending domains, attacks and usage statistics.

Data Engineers of Netflix — Interview with Dhevi Rajendran

Post Syndicated from Netflix Technology Blog original https://netflixtechblog.com/data-engineers-of-netflix-interview-with-dhevi-rajendran-a9ab7c7b36e5

Data Engineers of Netflix — Interview with Dhevi Rajendran

Dhevi Rajendran

This post is part of our “Data Engineers of Netflix” interview series, where our very own data engineers talk about their journeys to Data Engineering @ Netflix.

Dhevi Rajendran is a Data Engineer on the Growth Data Science and Engineering team. Dhevi joined Netflix in July 2020 and is one of many Data Engineers who have onboarded remotely during the pandemic. In this post, Dhevi talks about her passion for data engineering and taking on a new role during the pandemic.

Before Netflix, Dhevi was a software engineer at Two Sigma, where she was most recently on a data engineering team responsible for bringing in datasets from a variety of different sources for research and trading purposes. In her free time, she enjoys drawing, doing puzzles, reading, writing, traveling, cooking, and learning new things.

Her favorite TV shows: Atlanta, Barry, Better Call Saul, Breaking Bad, Dark, Fargo, Succession, The Killing

Her favorite movies: Das Leben der Anderen, Good Will Hunting, Intouchables, Mother, Spirited Away, The Dark Knight, The Truman Show, Up

Dhevi, so what got you into data engineering?

While my background has mostly been in backend software engineering, I was most recently doing backend work in the data space prior to Netflix. One great thing about working with data is the impact you can create as an engineer.

At Netflix, the work that data engineers do to produce data in a robust, scalable way is incredibly important to provide the best experience to our members as they interact with our service.

Beyond the really interesting technical challenges that come with working with big data, there are lots of opportunities to think about higher-level domain challenges as a data engineer. In college, I had done human-computer interaction research on subtitles for the Deaf and hard-of-hearing as well as computational genomics research on Alzheimer’s disease. I’ve always enjoyed learning about new areas and combining this knowledge with my technical skills to solve real-world problems.

What drew you to Netflix?

Netflix’s mission and its culture primarily drew me to Netflix. I liked the idea of being a part of a company that brings joy to so many members around the world with an incredibly powerful platform for their stories to be heard. The blend of creativity and a strong engineering culture at Netflix really appealed to me.

The culture was also something that piqued my interest. I was pretty skeptical of Netflix’s culture memo at first. Many companies have lofty ideals that don’t necessarily translate into the reality of the company culture, so I was surprised to see how consistently the culture memo aligns with the actual culture at the company. I’ve found the culture of freedom and responsibility empowering.

Rather than the typical top-down approach many companies use, Netflix trusts each person to make the right decisions for the company by using their deep knowledge of the problems they’re solving along with the context they gather from their leaders and stakeholders.

This means a lot less red tape, a lot less friction, and a lot more freedom for everyone at the company to do what’s best for the business. I also really appreciate the amount of visibility and input we get into broader strategic decisions that the company makes.

Finally, I was also really excited about joining the Growth Data Engineering team! My team is responsible for building data products relating to how we connect with our new members around the world, which is high-impact and has far-reaching global significance. I love that I get to help Netflix connect with new members around the world and help shape the first impression we make on them.

What is your favorite project or a project that you’re particularly proud of?

I have been primarily involved in the payments space. Not a project per se, but one of the things I’ve enjoyed being involved in is the cross-functional meetings with peers and stakeholders who are working in the payments space. These meetings include product managers, designers, consumer insights researchers, software engineers, data scientists, and people in a wide variety of other roles.

I love that I get to work cross-functionally with such a diverse group of people looking at the same set of problems from a variety of unique perspectives.

In addition to my day-to-day technical work, these meetings have provided me with the opportunity to be involved in the high-level product, design, and strategic discussions, which I value. Through these cross-functional efforts, I’ve also really gotten to learn and appreciate the nuances of payments. From using credit cards (which are fairly common in the US but not as widely adopted outside the US) to physically paying in person, members in different countries prefer to pay for our subscription in a wide variety of ways. It’s incredible to see the thoughtful and deeply member-driven approach we use to think about something as seemingly routine, straightforward, and often taken for granted as payments.

What was it like taking on a new role during the pandemic?

First off, I feel very lucky to have found a new role in this very difficult period. With the amount of change and uncertainty, the past year brought, it somehow felt both fitting and imprudent to voluntarily add a career change to the mix. The prospect was daunting at first. I knew there would be a bunch for me to learn coming into Netflix, considering that I hadn’t worked with the technologies my team uses (primarily Scala and Spark). Looking back now, I’m incredibly grateful for the opportunity and glad that I took it. I’ve already learned so much in the past six months and am excited about how much more I can learn and the impact I can make going forward.

Onboarding remotely has been a unique experience as well. Building relationships and gathering broader context are more difficult right now. I’ve found that I’ve learned to be more proactive and actively seek out opportunities to get to know people and the business, whether through setting up coffee chats, reading memos, or attending meetings covering topics I want to learn more about. I still haven’t met anyone I work with in person, but my teammates, my manager, and people across the company have been really helpful throughout the onboarding process.

It’s been incredible to see how gracious people are with their time and knowledge. The amount of empathy and understanding people have shown to each other, including to those who are new to the company, has made taking the leap and joining Netflix a positive experience.

Learning more

Interested in learning more about data roles at Netflix? You’re in the right place! Keep an eye out for our open roles in Data Science and Engineering here. Our culture is key to our impact and growth: read about it here.

Data Engineers of Netflix — Interview with Dhevi Rajendran was originally published in Netflix TechBlog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Securing and managing multi-cloud Presto Clusters with Grab’s DataGateway

Post Syndicated from Grab Tech original https://engineering.grab.com/data-gateway

Introduction

Data is the lifeblood of Grab and the insights we gain from it drive all the most critical business decisions made by Grabbers and our leaders every day.

Grab’s Data Engineering (DE) team is responsible for maintaining the data platform, which consists of data pipelines, job schedulers, and the query/computation engines that are the key components for generating insights from data. SQL is the core language for analytics at Grab and as of early 2020, our Presto platform serves about 200 user groups that add up to 500 users who run 350,000 queries every day. These queries span across 10,000 tables that process up to 1PB of data daily.

In 2016, we started the DataGateway project to enable us to manage data access for the hundreds of Grabbers who needed access to Presto for their work. Since then, DataGateway has grown to become much more than just an access control mechanism for Presto. In this blog, we want to share what we’ve achieved since the initial launch of the project.

The problems we wanted to solve

As we were reviewing the key challenges around data access in Grab and assessing possible solutions, we came up with this prioritized list of user requirements we wanted to work on:

  • Use a single endpoint to serve everyone.
  • Manage user access to clusters, schemas, tables, and fields.
  • Provide seamless user experience when presto clusters are scaled up/down, in/out, or provisioned/decommissioned.
  • Capture audit trail of user activities.

To provide Grabbers with the critical need of interactive querying, as well as performing extract, transform, load (ETL) jobs, we evaluated several technologies. Presto was among the ones we evaluated, and was what we eventually chose although it didn’t meet all of our requirements out of the box. In order to address these gaps, we came up with the idea of a security gateway for the Presto compute engine that could also act as a load balancer/proxy, this is how we ended up creating the DataGateway.

DataGateway is a service that sits between clients and Presto clusters. It is essentially a smart HTTP proxy server that is an abstraction layer on top of the Presto clusters that handles the following actions:

  1. Parse incoming SQL statements to get requested schemas, tables, and fields.
  2. Manage user Access Control List (ACL) to limit users’ data access by checking against the SQL parsing results.
  3. Manage users’ cluster access.
  4. Redirect users’ traffic to the authorized clusters.
  5. Show meaningful error messages to users whenever the query is rejected or exceptions from clusters are encountered.

Anatomy of DataGateway

The DataGateway’s key components are as follows:

  • API Service
  • SQL Parser
  • Auth framework
  • Administration UI

We leveraged Kubernetes to run all these components as microservices.

Figure 1. DataGateway Key Components
Figure 1. DataGateway Key Components

API Service

This is the component that manages all users and cluster-facing processes. We integrated this service with the Presto API, which means it appears to be the same as a Presto cluster to a client. It accepts query requests from clients, gets the parsing result and runs authorization from the SQL Parser and the Auth Framework.

If everything is good to go, the API Service forwards queries to the assigned clusters and continues the entire query process.

Auth Framework

This handles both authentication and authorization requests. It stores the ACL of users and communicates with the API Service and the SQL Parser to run the entire authentication process. But why is it a microservice instead of a module in API Service, you ask? It’s because we keep evolving the security checks at Grab to ensure that everything is compliant with our security requirements, especially when dealing with data.

We wanted to make it flexible to fulfill ad-hoc requests from the security team without affecting the API Service. Furthermore, there are different authentication methods out there that we might need to deal with (OAuth2, SSO, you name it). The API Service supports multiple authentication frameworks that enable different authentication methods for different users.

SQL Parser

This is a SQL parsing engine to get schema, tables, and fields by reading SQL statements. Since Presto SQL parsing works differently in each version, we would compile multiple SQL Parsers that are identical to the Presto clusters we run. The SQL Parser becomes the single source of truth.

Admin UI

This is a UI for Presto administrators to manage clusters and user access, as well as to select an authentication framework, making it easier for the administrators to deal with the entire ecosystem.

How we deployed DataGateway using Kubernetes

In the past couple of years, we’ve had significant growth in workloads from analysts and data scientists. As we were very enthusiastic about Kubernetes, DataGateway was chosen as one of the earliest services for deployment in Kubernetes. DataGateway in Kubernetes is known to be highly available and fully scalable to handle traffic from users and systems.

We also tested the HPA feature of Kubernetes, which is a dynamic scaling feature to scale in or out the number of pods based on actual traffic and resource consumption.

Figure 2. DataGateway deployment using Kubernetes
Figure 2. DataGateway deployment using Kubernetes

Functionality of DataGateway

This section highlights some of the ways we use DataGateway to manage our Presto ecosystem efficiently.

Restrict users based on Schema/Table level access

In a setup where a Presto cluster is deployed on AWS Amazon Elastic MapReduce (EMR) or Elastic Kubernetes Service (EKS), we configure an IAM role and attach it to the EMR or EKS nodes. The IAM role is set to limit the access to S3 storage. However, the IAM only provides bucket-level and file-level control; it doesn’t meet our requirements to have schema, table, and column-level ACLs. That’s how DataGateway is found useful in such scenarios.

One of the DataGateway services is an SQL Parser. As previously covered, this is a service that parses and digs out schemas and tables involved in a query. The API service receives the parsing result and checks against the ACL of users, and decides whether to allow or reject the query. This is a remarkable improvement in our security control since we now have another layer to restrict access, on top of the S3 storage. We’ve implemented an SQL-based access control down to table level.

As shown in the Figure 3, user A is trying run a SQL statement select * from locations.cities. The SQL Parser reads the statement and tells the API service that user A is trying to read data from the table cities in the schema locations. Then, the API service checks against the ACL of user A. The service finds that user A has only read access to table countries in schema locations. Eventually, the API service denies this attempt because user A doesn’t have read access to table cities in the schema locations.

Figure 3. An example of how to check user access to run SQL statements
Figure 3. An example of how to check user access to run SQL statements

The above flow shows an access denied result because the user doesn’t have the appropriate permissions.

Seamless User Experience during the EMR migration

We use AWS EMR to deploy Presto as an SQL query engine since deployment is really easy. However, without DataGateway, any EMR operations such as terminations, new cluster deployment, config changes, and version upgrades, would require quite a bit of user involvement. We would sometimes need users to make changes on their side. For example, request users to change the endpoints to connect to suitable clusters.

With DataGateway, ACLs exist for each of the user accounts. The ACL includes the list of EMR clusters that users are allowed to access. As a Presto access management platform, here the DataGateway redirects user traffics to an appropriate cluster based on the ACL, like a proxy. Users always connect to the same endpoint we offer, which is the DataGateway. To switch over from one cluster to another, we just need to edit the cluster ACL and everything is handled seamlessly.

Figure 4. Cluster switching using DataGateway
Figure 4. Cluster switching using DataGateway

Figure 4 highlights the case when we’re switching EMR from one cluster to another. No changes are required from users.

We executed the migration of our entire Presto platform from an AWS EMR instance to another AWS EMR instance using the same methodology. The migrations were executed with little to no disruption for our users. We were able to move 40 clusters with hundreds of users. They were able to issue millions of queries daily in a few phases over a couple of months.

In most cases, users didn’t have to make any changes on their end, they just continued using Presto as usual while we made the changes in the background.

Multi-Cloud Data Lake/Presto Cluster maintenance

Recently, we started to build and maintain data lakes not just in one cloud, but two – in AWS and Azure. Since most end-users are AWS-based, and each team has their own AWS sub-account to run their services and workloads, it would be a nightmare to bridge all the connections and access routes between these two clouds from end-to-end, sub-account by sub-account.

Here, the DataGateway plays the role of the multi-cloud gateway. Since all end-users’ AWS sub-accounts have peered to DataGateway’s network, everything becomes much easier to handle.

For end-users, they retain the same Presto connection profile. The DE team then handles the connection setup from DataGateway to Azure, and also the deployment of Presto clusters in Azure.

When all is set, end-users use the same endpoint to DataGateway. We offer a feature called Cluster Switch that allows users to switch between AWS Presto cluster and Azure Presto Cluster on the fly by filling in parameters on the connection string. This feature allows users to switch to their target Presto cluster without any endpoint changes. The switch works instantly whenever they do the change. That means users can run different queries in different clusters based on their requirements.

This feature has helped the DE team to maintain Presto Cluster easily. We can spin up different Presto clusters for different teams, so that each team has their own query engine to run their queries with dedicated resources.

Figure 5. Sub-account connections and Queries
Figure 5. Sub-account connections and Queries

Figure 5 shows an example of how sub-accounts connect to DataGateway and run queries on resources in different clouds and clusters.

Figure 6. Sample scenario without DataGateway
Figure 6. Sample scenario without DataGateway

Figure 6 shows a scenario of what would happen if DataGatway doesn’t exist. Each of the accounts would have to maintain its own connections, Virtual Private Cloud (VPC) peering, and express link to connect to our Presto resources.

Summary

DataGateway is playing a key role in Grab’s entire Presto ecosystem. It helps us manage user access and cluster selections on a single endpoint, ensuring that everyone is running their Presto queries on the same place. It also helps distribute workload to different types and versions of Presto clusters.

When we started to deploy the DataGateway on Kubernetes, our vision for the Presto ecosystem underwent an epic change as it further motivated us to continuously improve. Since then, we’ve had new ideas on deployment method/pipeline, microservice implementations, scaling strategy, resource control, we even made use of Kubernetes and designed an on-demand, container-based Presto cluster provisioning engine. We’ll share this in another engineering blog, so do stay tuned!.

We also made crucial enhancements on data access control as we extended Presto’s access controls down to the schema/table-level.

In day-to-day operations, especially when we started to implement data lake in multiple clouds, DataGateway solved a lot of implementation issues. DataGateway made it simpler to switch a user’s Presto cluster from one cloud to another or allow a user to use a different Presto cluster using parameters. DataGateway allowed us to provide a seamless experience to our users.

Looking forward, we’ve more and more ideas for our Presto ecosystem, such Spark DataGateway or AWS Athena integrations, to keep our data safe at any time and to provide our users with a smoother experience when dealing with data used for analysis or research.

Authored by Vinnson Lee on behalf of the Presto Development Team at Grab – Edwin Law, Qui Hieu Nguyen, Rahul Penti, Wenli Wan, Wang Hui and the Data Engineering Team.

Join us

Grab is more than just the leading ride-hailing and mobile payments platform in Southeast Asia. We use data and technology to improve everything from transportation to payments and financial services across a region of more than 620 million people. We aspire to unlock the true potential of Southeast Asia and look for like-minded individuals to join us on this ride.

If you share our vision of driving South East Asia forward, apply to join our team today.