Loris comments

content/log/2022/how-uber-uses-zig.md

@@ -9,11 +9,11 @@ Disclaimer: I work at Uber and am partially responsible for bringing `zig cc`
 to serious internal use. Opinions are mine, this blog post is not affiliated
 with Uber.
 
-I talked at [Zig Milan][zig-milan] meetup about "Onboarding Zig at Uber".
+I talked at the [Zig Milan][zig-milan] meetup about "Onboarding Zig at Uber".
 This post is a little about "how Uber uses Zig", and more about "my experience
 of bringing Zig to Uber", from both technical and social aspects.
 
-The video is [here][milan-youtube]. The rest of the post is a loose
+<big>The video is [here][milan-youtube]</big>. The rest of the post is a loose
 transcript, with some commentary and errata.
 
 {{<img src="_/2022/uber-zig-frank-tweet.jpg"
@@ -26,10 +26,12 @@ transcript, with some commentary and errata.
 
 TLDR:
 
-* Uber uses zig to compile its C/C++ code. Now only in the [Go
+* Uber uses Zig to compile its C/C++ code. Now only in the [Go
   Monorepo][go-monorepo] via [bazel-zig-cc][bazel-zig-cc], with plans to
   possibly expand use of `zig cc` to other languages that need a C/C++
   toolchain.
+* Main selling points of C/C++ toolchain on top of zig-cc over the
+  alternatives: configurable versions of glibc and macOS cross-compilation.
 * Uber does not have any plans to use zig-the-language yet.
 * Uber signed a support agreement with Zig Software Foundation (ZSF) to
   prioritize bug fixes. The contract value is disclosed in the ZSF financial
@@ -61,11 +63,11 @@ thousand engineers. In short, it's big.
     hint="graph"
     >}}
 
-I can't tell this better than my colleague [Abhinav Gupta][abg] from the Go
+I can't say this better than my colleague [Abhinav Gupta][abg] from the Go
-Platform team (the transcript is available in the "alt" attribute):
+Platform team (a transcript is available in the "alt" attribute):
 
 At this point of the presentation, since I explained (thanks abg!) how Uber
-uses zig, I could end the talk. But you all came in for the process, so after
+uses Zig, I could end the talk. But you all came in for the process, so after
 an uncomfortable pause, I decided to tell more about it.
 
 {{<div-clear>}}
@@ -102,7 +104,7 @@ it also was not painful *enough* to be picked up.
 At this point it is important to understand the limitations of a non-hermetic
 C++ toolchain:
 - Cannot cross-compile. So we can't compile Linux executables on a Mac if they
-  have CGo (which many of our services do). This was worked around by... not
+  require CGo (which many of our services do). This was worked around by... not
   cross-compiling.
 - CGo executables would link to a glibc version that was found on the system.
   That means: when upgrading the OS (multi-month effort), the build fleet must
@@ -131,7 +133,7 @@ Bazel's toolchain documentation, and I didn't find a good example to rely on.
 In January of 2021 I found Andrew Kelley's blog post [`zig cc`: a Powerful
 Drop-In Replacement for GCC/Clang][zig-cc-andrewrk]. I recommend reading the
 article; it changed how I think about compilers (and it will help you
-understand the remaining article better, because I gave the talk to the Zig
+understand the remaining article better, because I gave the talk to a Zig
 audience). To sum up the Andrew's article, `zig cc` has the following
 advantages:
 
@@ -151,8 +153,8 @@ of `zig ar`, which Bazel relies on.
 
 ### 2021 Feb: asking for attention
 
-I [reported bugs][zig-motiejus-issues] to zig. Nothing happened for a
+I [reported bugs][zig-motiejus-issues] to Zig. Nothing happened for a
-week. I donated $50/month, expecting "the zig folks" to prioritize what I've
+week. I donated $50/month, expecting "the Zig folks" to prioritize what I've
 reported. A week of silence again. And then I dropped the bomb in
 `#zig:libera.chat`:
 
@@ -162,7 +164,7 @@ reported. A week of silence again. And then I dropped the bomb in
 <andrewrk> did you get a different impression somewhere?
 ```
 
-Oops. At the time I hoped that whoever notice the conversation will immediately
+Oops. At the time I hoped that whoever notice the conversation would immediately
 forget it. Well, here it is again, more than a year later, over here, for your
 enjoyment.
 
@@ -190,35 +192,36 @@ CI. It failed almost all tests.
 Most of the failures were caused by dependencies on system libraries. At this
 point it was clear that, to truly onboard bazel-zig-cc and compile **all** it's
 C/C++ code, there needs to be quite a lot of investment to remove the
-dependency on system libraries and undoing of a lot of tech debt.
+dependency on system libraries and undoing of a lot of technical debt.
 
 ### 2021 End: recap
 
 - Various places at Uber would benefit from a hermetic C++ cross-compiler, but
-  it's not funded due to a large investment and not enough justification.
+  it's not funded due to requiring a large investment and not naving enough
+  justification.
 - bazel-zig-cc kinda works, but both bazel-zig-cc and zig cc have known bugs.
 - I can't realistically implement the necessary changes or bug fixes. I tried
   implementing `zig ar`, a trivial front-end for llvm's `ar`, and failed.
 - Once an issue had been identified as a Zig issue, getting attention from Zig
   developers was unpredictable. Some issues got resolved within days, some took
-  more than 6 months. Donations don't change `zig cc` priorities.
+  more than 6 months, and donations din't change `zig cc` priorities.
 - The monorepo-onboarding diff was simmering and waiting for it's time.
 
 ### 2021 End: Uber needs a cross-compiler
 
 I was tasked to evaluate arm64 for Uber. Evaluation details aside, I needed to
 compile software for linux-arm64. Lots of it! Since most of our low-level infra
-is in Go monorepo, I needed a cross-compiler there first.
+is in the Go monorepo, I needed a cross-compiler there first.
 
 A business reason for a cross-compiler landed on my lap. Now now both time and
 money can be invested there. Having a "WIP diff" with `zig cc` was a good
-start, but was still very far from over: teams were not convinced it's the
+start, but was still very far from over: teams were not convinced it was the
 right thing to do, the diff was too much of a prototype, and both zig-cc and
 bazel-zig-cc needed lots of work before they could be used at any capacity at
 Uber.
 
 When onboarding such a technology in a large corporation, the most important
-thing to manage is risk. As zig is a novel technology (not even 1.0!), it was
+thing to manage is risk. As Zig is a novel technology (not even 1.0!), it was
 truly unusual to suggest compiling all of our C and C++ code with it. We should
 be planning to stick with it for at least a decade. Questions were raised and
 evaluated with great care and scrutiny. For that I am truly grateful to the Go
@@ -235,26 +238,26 @@ Given that we now needed a cross-compiler, we had two candidates:
   uncertain, used-by-nobody, but quite a tempting solution.
 
 `zig cc` provides a few extra features on top of `bazel-toolchain`:
-- configurable glibc version. In grailbio case you would need a sysroot
+- configurable glibc version. With `grailbio` you would need a sysroot
   (basically, a chroot with the system libraries, so the programs can be linked
-  against them), which needs to be maintained.
+  against them), which would need to be maintained.
 - a working, albeit still buggy, hermetic (cross-)compiler for macOS.
 
-Glibc we can handle in either case. However, `bazel-toolchain` will unlikely
+We would be able to handle glibc with either, however, `grailbio` is unlikely
-ever have a way to compile to macOS, let alone cross-compile. Relying on the
+to ever have a way to compile to macOS, let alone cross-compile. Relying on the
-system compiler is undesirable on developer laptops, and Go Platform feels that
+system compiler is undesirable on developer laptops, and the Go Platform feels
-first-hand, especially during macOS upgrades.
+that first-hand, especially during macOS upgrades.
 
-The prospect of a hermetic toolchain for macOS targets tripped the scales
+The prospect of a hermetic toolchain for macOS targets tipped the scales
 towards `zig cc`, with all its warts, risks and instability.
 
-There was another, attention problem: if we were considering the use of Zig in
+There was still another problem, one of attention: if we were considering the
-a serious capacity, we knew we will hit problems, but would be unlikely to have
+use of Zig in a serious capacity, we knew we will hit problems, but would be
-the expertise to solve them. How can we, as a BigCorp, de-risk the engagement
+unlikely to have the expertise to solve them. How can we, as a BigCorp, de-risk
-question, making sure that bugs important to us are handled timely? We were
+the engagement question, making sure that bugs important to us are handled
-sure of good intentions of ZSF: it was obvious that, if we find and report a
+timely? We were sure of good intentions of ZSF: it was obvious that, if we find
-legitimate bug, it would get fixed. But how can we put an upper bound on
+and report a legitimate bug, it would get fixed. But how can we put an upper
-latency?
+bound on latency?
 
 ### Money
 
@@ -269,11 +272,11 @@ Contract terms were roughly as follows:
 - Hack hack hack hack hack.
 - When done, Loris enters the number of hours worked on the issue.
 
-Uber has the right to *time* of ZSF members. We have no decision or voting
+Uber has a right to ZSF members' *time*. We have no decision or voting power
-power whatsoever with regards to Zig. We have right to offer suggestions, but
+whatsoever with regards to Zig. We have right to offer suggestions, but they
-they have been and will be treated just like from any other third-party
+have been and will be treated just like from any other third-party bystander.
-bystander. We did not ask for special rights, it's explicit in the contract,
+We did not ask for special rights, it's explicit in the contract, and we don't
-and we don't want that.
+want that.
 
 The contract was signed, the wire transfer completed, and in 2022 January we
 had:
@@ -284,7 +287,7 @@ had:
   and hermetic.
 
 {{<img src="_/2022/uber-zig-deposit.png"
-    alt="Wire transfer of $52800 from Uber to Zig Software Foundation"
+    alt="Wire of $52800 from Uber to Zig Software Foundation"
     caption="The amount of money that changed hands is public, because ZSF is a nonprofit."
     hint="graph"
     >}}
@@ -341,7 +344,7 @@ sister teams in Seattle and Bay Area are hiring too. Ping me.
 Credits
 -------
 
-Many thanks Abhinav Gupta for reading drafts of this.
+Many thanks Abhinav Gupta and Loris Cro for reading drafts of this.
 
 [^1]: Errata: I incorrectly said "by an order of magnitude". The order of
   magnitude is the same.