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Author: mattchung

  • Daily Review: Day ending in 2020/11/11

    Daily Review: Day ending in 2020/11/11

    The last couple days at work have taken a toll on me emotionally. To lift me up, Jess used her arts and crafts skills to make a doll — made from Metric’s shedded hair (see featured image).

    Family

    • Felt myself tear up when pushing Elliott in the stroller. The two of us were having a blast while walking the dogs at the local park this morning. With Elliott strapped into her stroller, I pushed her across the green grassy park, the two of us racing against our imaginary nascar opponents. Elliott had such a blast and there was a little wrinkle in her nose and she put on a wide smile. And in that moment, a tremendous amount of sadness poured over me — totally unexpected emotion. Suddenly I was reminded of my own child hood and how often I felt alone … I never want Elliott to feel that same way. Isn’t that the point of parenting? Making our children’s lives a little (or a lot) better than ours? It’s true when they say that your children will bring out your best and worst memories from childhood. And this was my first experience of own childhood creeping back into my parenting life … I wonder what’s in store for me in the future.

    Work

    • Reviewed pull requests from multiple colleagues. As a project lead, I’m trying my best to divide my own time between implementing features while ensuring that the project makes forward progress.
    • Read through the description and lightly scanned all the outstanding pull requests against our code base. With 50+ developers working on the team, it’s nearly impossible to stay on top of what features are being developed. One way to stay in touch is to simply read through the pull requests that are coming through.
    • Finished filling out the threat model for a security review that I’m submitting. Many of the questions are unrelated to the feature that I’m launching.

    Graduate School

    • Laid out the threading model that allows me and my project partner to use synchronous communication over gRPC while achieving asynchronous handling.

    Writing

    • Published a blog post on how to build and easily test grpc service using a command line tool. After writing up the blog post that targets other students enrolled in my advanced operating systems course, I posted the link on Piazza and it was nice to see that my write up will assist other students, the entire point of me spending an extra 30 minutes writing the documentation.
  • Testing your gRPC services using grpc_cli

    Testing your gRPC services using grpc_cli

    This post may be helpful for you if you are building gRPC services and want a convenient way to test your service using a command line tool. Similar to using cURL when testing HTTP(s) services, I wanted an easy way to test the gRPC services that I’m building.

    Originally, I had originally planned to whip together a tiny C++ program that sends protobuf messages to my MapReduce service that I’m building for advanced operating systems course. Fortunately, a testing tool already exists: grpc_cli. Even better is that the tool ships with the grpc source code.

    So follow along if you want to install the grpc command line tool, enable server reflection, and execute a few examples.

    Note: This post assumes that you are programming in C++ and your operating system is Ubuntu

    Install grpc_cli

    Follow the steps below if you are running on Ubuntu. If you are running gRPC on your mac, then you’ll want to substitute the apt-get command with brew install, as described in the grpc command line documentation.

    1. Clone the grpc repository

      [code lang=”bash”]git clone git@github.com:grpc/grpc.git[/code]

    2. Add submodules

      [code lang=”bash”]$ git submodule update –init[/code]

    3. Install libflags-dev

      [code lang=”bash”]$ sudo apt-get install libgflags-dev[/code]

    4. Compile grpc

      [code lang=”bash”]$ mkdir -p cmake/build
      $ cd cmake/build
      $ cmake -DgRPC_BUILD_TESTS=ON ../..
      $ make grpc_cli
      [/code]

    Enable Reflection for your service

    In your grpc service code, before you bind and listen, you’ll need to enable reflection. Although not entirely necessary for interacting with your service, not having reflection enabled means you cannot use many of the grpc_cli commands like list.

    [code lang=”bash”]
    grpc::reflection::InitProtoReflectionServerBuilderPlugin();
    grpc::ServerBuilder builder;
    builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
    builder.RegisterService(&service);
    …
    [/code]

    Add grpc++_reflection library

    Make sure that you are adding grpc++ library when building your project. If you are a student in advanced operating systems, you’ll need to update GeneratedProtos.cmake and link the gRPC::grpc++_reflection library as follows:

    [code lang=”bash”]
    % git diff
    diff –git a/src/GenerateProtos.cmake b/src/GenerateProtos.cmake
    index c6a80bc..cce2d51 100644
    — a/src/GenerateProtos.cmake
    +++ b/src/GenerateProtos.cmake
    @@ -75,5 +75,5 @@ add_custom_command(
    )

    add_library(p4protolib ${ProtoHeaders} ${ProtoSources})
    -target_link_libraries(p4protolib PUBLIC protobuf::libprotobuf gRPC::grpc++)
    +target_link_libraries(p4protolib PUBLIC protobuf::libprotobuf gRPC::grpc++ gRPC::grpc++_reflection)
    target_include_directories(p4protolib PUBLIC ${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR})
    [/code]

     

    Using grpc_cli

    I’d encourage you to explore the grpc_cli by checking out the official user guide. However, for the purpose of this post, I want to show you how to list your service as well as how to invoke the “MapReduce” service.

    Examples

    Start your gRPC service

    In the example below, I’m staring my worker process that listens on localhost:50051. Here’s a snippet of my very bare service:

    [code lang=”proto3″]
    service MapReduce {
    rpc map(MapRequest) returns (MapResponse) {}
    rpc reduce(ReduceRequest) returns (ReduceResponse) {}
    [/code]

    Starting the service

    [code lang=”bash”]
    $ ./mr_worker localhost:50051
    Listening on ip address: localhost
    Listening on port: 50051
    Server listening on localhost:50051
    [/code]

    List the services

    After starting my service (that has reflection enabled), the service shows up when I execute the list command:

    [code lang=”bash”]
    $ ./grpc_cli ls localhost:50051
    masterworker.MapReduce
    grpc.reflection.v1alpha.ServerReflection
    grpc.health.v1.Health
    [/code]

    Invoking “MapReduce”

    [code lang=”bash”]
    $ ./grpc_cli call localhost:50051 masterworker.MapReduce.map "shard_data: ‘123’"
    connecting to localhost:50051
    Rpc succeeded with OK status
    [/code]

    Passing in multiple fields

    [code lang=”bash”]
    $ ./grpc_cli call localhost:50051 masterworker.MapReduce.reduce "filename: ‘123’ worker_hostname: ‘localhost’ worker_port: 50051"
    connecting to localhost:50051
    Rpc succeeded with OK status
    [/code]

    References

    • https://grpc.github.io/grpc/cpp/md_doc_server_reflection_tutorial.html
    • https://github.com/grpc/grpc/blob/master/doc/command_line_tool.md
    • https://stackoverflow.com/questions/61641174/unable-to-link-the-grpc-libraries-in-windows
  • 3 tips on getting eyeballs on your code review

    3 tips on getting eyeballs on your code review

    “Why is nobody reviewing my code?”

    I sometimes witness new engineers (or even seasoned engineers new to the company) submit code reviews that end up sitting idle, gaining zero traction. Often, these code reviews get published but comments never flow in, leaving the developer left scratching their head, wondering why nobody seems to be taking a look. To help avoid this situation, check out the 3 tips below for more effective code reviews.

    3 tips for more effective code reviews

    Try out the three tips for more effective code reviews. In short, you should:

    1. Assume nobody cares
    2. Strive for bite sized changes
    3. Add a descriptive summary

    1. Assume nobody cares

    After you hit the publish button, don’t expect other developers to flock to your code review. In fact, it’s safe to assume that nobody cares. I know, that sounds a bit harsh but as Neil Strauss suggests,

    “Your challenge is to assume — to count on — the completely apathy of the reader. And from there, make them interested.”

    At some point in our careers, we all fall into this trap. We send out a review, one that lacks a clear description (see section below “Add a descriptive summary”) and then the code review would sometimes sits there, patiently waiting for someone to sprinkle comments. Sometimes, those comments never come.

    Okay, it’s not that people don’t necessary care. It has more to do with the fact people are busy, with their own tasks and deliverable. They too are writing code that they are trying to ship. So your code review essentially pulls them away from delivering their own work. So, make it as easy as possible for them to review.

    One way to do gain their attention is simply by giving them a heads up.

    Before publishing your code review, send them an instant message or e-mail, giving them a heads up. Or if you are having a meeting with that person, tell them that you plan on sending out a code review and ask them if they can take a look at the code review. This puts your code review on their radars. And if you don’t see traction in an appropriate (which varies, depending on change and criticality), then follow up with them.

    2. Strive for bite sized code reviews

    Anything change beyond than 100-200 lines of code requires a significant amount of mental energy (unless the change itself is a trivial updates to comments or formatting). So how can you make it easier for your reviewer?

    Aim for small, bite sized code reviews.

    In my experience, a good rule of them is submit less than 100 lines of code. What if there’s no way your change can squeeze into double digits? Then consider breaking down the single code review into multiple, smaller sized code reviews and once all those independent code reviews are approved, submit a single code review that merges all those changes in atomically.

    And if you still cannot break down a large code review into these lengths and find that it’s unavoidable to submit a large code review, then make sure you schedule a 15-30 minute meeting to discuss your large code review (I’ll create a separate blog post for this).

    3. Add a descriptive summary for the change

    I’m not suggesting you write a miniature novel when adding a description to your code review. But you’ll definitely need to write something with more substance than a one-liner: “Adds new module”. Rob Pike put’s it succinctly and his criteria for a good description includes “What, why, and background”.

    In addition to adding this criteria, be sure to describe how you tested your code — or, better yet, ship your code review with unit tests. Brownie points if you explicitly call out what is out of scope. Limiting your scope reduces the possibility of unnecessary back-and-forth comments for a change that falls outside your scope.

    Finally, if you want some stricter guidelines on how to write a good commit message, you might want to check out Kabir Nazir’s blog post on “How to write good commit messages.”

    Summary

    If you are having trouble with getting traction on your code reviews, try the above tips. Remember, it’s on you, the submitter of the code review, to make it as easy as possible for your reviews to leave comments (and approve).

    Let’s chat more and connect! Follow me on Twitter: @memattchung

  • Daily Review – Day ending in 2020/11/05

    Daily Review – Day ending in 2020/11/05

    Family

    • Assembled our Berkey water filtering system. The instructions are quite complicated, actually. In addition to reading the manuals, I had to pull up a couple instructional YouTube videos to make sure that I was priming the filters correctly.
    • Took Elliott on a late night walk. She had missed her nap and we needed to stretch her and keep her awake until her 7pm bed time.

    Work

    • Spent about an hour or so chipping away at codifying our operational dashboard, as part of hackathon.
    • Read through a ton of documentation and watched a couple videos on virtual private connection (VPC). I should’ve read and watched all this training when I first joined the organization. Oh well. At least the material makes more sense now, now that I’ve had first hand exposure to the dataplane code. Anyways, all this material helped me build a better mental model needed to deliver my tech talk.

    Graduate School

    • The word coordinator kept popping up in the lectures. This coordinator often shows up in different code bases and systems within Amazon and I didn’t realize that the term has roots in the theory of distributed systems.
    • Learning more about the value of checkpoints. I can definitely see me adopting and integrating checkpoints into the software I design and build, at least for the stateful applications that need to have robust recovery mechanisms.
    • I’d like to learn more about two phase commit protocol. Similar to the word coordinator, two phase commit protocol term continues to pop up in the lectures and I bet it’s worth learning more about the specifics of this transaction strategy.
    • Window of vulnerability. The trade off between persisting in memory log records to disk
  • Daily Review – Day ending in 2020/11/04

    Daily Review – Day ending in 2020/11/04

    My favorite part of the day was waking up to a video that Jess recorded while I was asleep, a video capturing a little frog dancing on our window facing the backyard. My wife: she’s super cute.

    Work

    • Hosted and moderated a tech panel on career growth and promotions. On behalf of Asians@ at Amazon, I lead a conversational fire side chat with four (Asian) senior software development engineers about some of the non technical barriers that our community often faces throughout our career. Not speaking up. Not advocating for one self. Everyone on the panel nailed it (despite how nervous they were) and I look forward to creating and hosting new events in the future.

    Health

    • Fought off a killer headache that kicked in after I ate che (a Vietnamese dessert). My body rejects processed sugars and when I consume too much of it, my body sends me a strong signal in the form of a painful headache that lasts several hours, the only way to fight it off is to gulp down as much water as possible and flush the sugars out of my system.

    Daily Photo

    Dancing frog on the window
  • Daily Review – Day ending in 2020/11/03

    Daily Review – Day ending in 2020/11/03

    Family

    • Jess and I felt nervous about the presidential election results while watching the news online. Despite Biden leading in the polls, just as Hilary four years ago back in 2016, I’m sitting at the edge of my seat as the results come in, not confident at all that Biden can pull off a victory. Again, as I mentioned in earlier posts, although I cast my vote for Biden, I’m more voting to get Trump out.

    Graduate School

    • Learned of a brilliant technique to simplify crash recovery by removing an edge case and exercising the same code as the abort transaction. Technique from RioVista papers. The crash recovery is also idempotent so it can withstand power failure during the crash recovery itself. Idempotent. First heard of this term when I was learning Ansible back in the day. Something to think about again.

    Work

    • Checked in some GRE header code that basically implements RFC 2784 and 2890. Stepping through the RFC, I learned how much unnecessary overhead the protocol carries with it. A 3 bit version field that MUST always be zero? Granted, I understand that the protocol designers were trying to future proof the protocol but now I understand why a protocol like IPIP prevails given that IPIP will encapsulate only IP.

     

  • Daily Review – Day ending in 2020/11/02

    Daily Review – Day ending in 2020/11/02

    Family

    Elliott and I drove to Lowe’s home improvement store and picked up a new faucet. Normally, Elliott will cry after sitting in the car for more than 10 minutes but not this trip. She did amazing and the two us had a blast at Lowe’s and she helped me select our new faucet since the one installed in our kitchen busted, causing water to leak into and underneath the sink. Luckily, my dad is in town and helped replace the existing broken faucet with the one I just purchased.

    Graduate School

    Submitted project 3 assignment on gRPC and multi-threading. Similar to project 2, I partnered up with another Seattle based student (who also happens to be Vietnamese as well) and we divided the work down the middle and stitched our code together.

    Watched half the lectures on RioVista. This lecture series seems to be a continuation of the last lecture series (on lightweight recoverable virtual machines), adding on top of the idea of using transactions to keep a log record of changes to the virtual memory address space. The key different with RioVista though is that they are targeting performance as their primary goal.

    Health

    Walked about 3 miles on the treadmill yesterday while working and studying. Last week, I could not find the remote that controls my treadmill but luckily Jess found it buried in the back of my office and luckily I was able to get some exercise in.

    Work

    Held a dry-run kick off meeting for a panel that I’m hosting and moderating this upcoming Wednesday. The purpose of the panel is to give people a sense of what it looks like to grow one’s career as a software engineer at Amazon.

  • Weekly Review – Week ending in 2020/11/01

    Weekly Review – Week ending in 2020/11/01

    No Halloween this year

    I used to love Halloween growing up, not so much the dressing up part but the knocking on doors and getting handed fist fulls of candy. Now, as an adult, I love returning the favor and always think about giving out larger than average candy and chocolate.

    But not this year, thanks to COVID-19.

    Hopefully 2020 will be the one and only year that we skip Halloween …

    Starting writing my first e-book

    I’m compiling all my blog posts on “advanced operating systems refresher” into a single, nicely formatted e-book. The book will provide a summary and detailed notes on Udacity’s Advanced Refresher course.

    Media Consumption

    Watched the first two episodes of “This is Us”. Again, as I mentioned in my blog posts, the writer’s (and cast and crew) deserve a huge applaud for pivoting and incorporating two major events in history — the COVID-19 pandemic and police brutality on black lives — into the story line. That’s no easy feat but they are pulling it off.

    Watched Borat subsequent film. I found the film hilarious and ingenious. Reveals how complicated people can be. For example, two trump supporters end up taking Borat into their homes and at one point, they even speak up on behalf of women.

    Home Care

    I’m super motivated keeping our new home in tip top shape. I had learned that the previous owner’s took a lot of pride in the house, the retired couple out in the front or back yard on a daily basis, the two of them maintaining the lawn and plants.

    Learning how to take care of the lawn. That includes learning the different modes of mowing (i.e. mulching, side discharge, bagging), the difference between slow release and fast release nitrogen, the importance of aerating, the importance of applying winterizer two weeks before the last historical freeze day, how to edge properly and so on.

    Family

    Still working from home and still appreciate the little gestures from Jess throughout the day. I sometimes get lost in a black hole of thoughts and troubleshooting, not drinking any water or eating snacks for hours at a time. So the little snacks that Jess drops off go a long way.

    Health

    Although taking care of mental health, not so much physical health. Only exercised once last week which was basically jogging on the treadmill.

    Graduate School

    Applied theory of lightweight recoverable virtual machine to work. In advanced operating systems, I took the concept of the abort transaction and suggested that we install a similar handler in our control plane code.

  • Daily Review – Day ending in 2020/11/01

    Daily Review – Day ending in 2020/11/01

    What a weird morning. Totally forgot the the time changed, the clock moving back an hour (i.e. we gain an hour), and found myself studying and working at 03:30 AM (instead of 04:30 AM). When I first woke up and glanced at my Casio watch, I debated whether to get out of bed or not since I was my body was telling me it needed a little more rest. However, knowing that Elliott would soon wake me up and knowing that I had a very small window of time to myself, I rolled out of bed. Parent life.

    Home care

    • Manually aerated the front yard using core aeration tool. The video advertisements for aerating make the process of aerating seem so pleasant. It’s not. It’s actually a lot of hard work and I broke a massive sweat aerating the front yard.I totally understand now why people rent aerating machines at Home Depot (or Lowe’s) for $20.00 bucks an hour. Renting a machine would make the work so much easier.
    • Fed the lawn fertilizer. After aerating the lawn, I poured about 2.2 pounds of fertilizer into the Ace branded bucket, transferred the food into the spreader, and then dispensed the it all over the front yard.

    Family

    • Family trip to Lam’s seafood located in Tequila. This Lam’s seafood location blows the other location (i.e. International District) out of the water. The location in Tequila is not only larger, but it’s cleaner and closely resembles the layout and feel of Uwajimaya.  Shopping in the store reminds me of growing up in Little Saigon, all the Vietnamese chatter and all the people bustling in the background.
    • Dropped off our ballot at the library located across the street. Just before sliding the ballot into the drop off box, I sat in the front seat of the car (with the two dogs next to me) with the Stranger’s cheat sheet opened up, filling out the last few choices that I was undecided.

     

  • Five tips for surviving (or thriving) in the OMSCS program as a computer science graduate student

    Five tips for surviving (or thriving) in the OMSCS program as a computer science graduate student

    Overview

    In this post, I’m sharing five tips that I’ve picked up over the last 2 years in the program. At the time of this writing, I’m wrapping up my 7th course (advanced operating systems) in the OMSCS program. This means that I have 3 more courses to complete until I graduate with my masters in computer science from Georgia Tech.

    This post assumes that you are already enrolled as a student in the program. If you are still on the fence as to whether or not you should join the program, check out Adrian’s blog post on “Georgia Tech Review: yes, maybe, no”. Very shortly, I’ll post my own thoughts and recommendations on whether or not I think you should join the program.

    Five Tips

    Prerequisites

    Before enrolling in a course, check the course’s homepage for recommended prerequisites. Once you are officially accepted into the program,  you’ll soon discover that unlike undergraduate, you can enroll in courses despite not meeting prerequisites. The upside of this relaxed approach is that students who are really eager to take a course can do so (assuming seats are available). The downside is that if you are not prepared for the course, you’ll be way in over your head and likely will drop the course within the first few weeks since many courses are front loaded.  For example, thinking about taking advanced operating systems? Before jumping the gun, take the diagnostic exam. Doing so will help you gauge whether or not you set up for success.

    Time management

    Manage your time by setting and schedule and sticking to it. If you are an early bird like me, carve out 50 minutes early in the morning, take a shot of your expresso, and get cracking.  Set specific times in which you will sit down and study (e.g. watch lectures, review notes, work on a project) and aim to stick to that schedule (as a new parent, I understand that plans often can easily be foiled).

    Trade offs

    Know when and what to slip or sacrifice. This is super important. We all 24 hours in a day. And we all have other responsibilities such as a full time job or children to take care of. Or something unexpectedly will just pop up in your life that demands your attention. That’s okay. Graduate school (and doing well in graduate school) is important. But there will be other competing motivators and sometimes, you’ll have to sacrifice your grade. That’s okay.

    Expectations

    Know what you want to get out of the program. What are you trying to get out of the program? Or what are you trying to get out of the current course you are enrolled in? Are you here to learn and improve your craft? Then focus on that. Or are you here to get a good grade? Then do that. Are you here to expand your network and potentially apply to a PhD program? Then make sure you attend the office hours and meet with the professors.

    Course reviews

    Read the reviews on OMSCentral.  If you haven’t read reviews on OMSCentral.com for the courses you plan to take (or are currently taking), please go and do that. Right now. On that website, you’ll find reviews from former students. They give you a better sense of what you’ll learn, what projects you’ll tackle, how engaged the professor is , whether the grades are curved, how difficulty the exams are, and maybe most important: how many hours you should expect to put into the course.

    Notifications

    Create e-mail (or text) notifications in your calendar for upcoming due dates. It sucks when you forget that an upcoming assignment is due soon. Sucks even more when you find out that the due date has passed. Although you can rely on Canvas (Georgia Tech’s current system for managing their courses), I still recommend using your own system.

    Summary

    The above tips do not guarantee a smooth journey. Chaos will somehow creep its way into our time and things will get derailed. That’s okay. Take a deep breathe and revisit the tip above on prioritization. Remind yourself why you are in graduate school. Now go out there and kick some ass.