jmmv.dev

test, [, and [[

A little essay on the amusement or horror that may bring to learn that both test and [ are binaries on your typical Unix system, and that [[ is subject to completely different rules.

March 25, 2020 · Tags: shell
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macOS terminal stalls running a binary

Here I am, confined to my apartment due to the COVID-19 pandemic and without having posted anything for almost two months. Fortunately, my family and I are still are in good condition, and I’m even more fortunate to have a job that can employ me remotely without problems. Or can they? For over a year, my team and I have been working on allowing our mobile engineers to work from their laptops (as opposed to from their powerful workstations).

March 23, 2020 · Tags: fuse, macos
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FOSDEM navigation 101

FOSDEM 2020 is over. As I type this, I’m on my way back home from the conference in Brussels. And it has been nice. In the end. I must confess I was frustrated by the middle of the first day, though things got better after that. Here is the thing: FOSDEM is not your usual conference. There are lots of things going on at once and all of them are crowded.

February 3, 2020 · Tags: conference
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Ensuring system rewrites are truly necessary

You probably know that software rewrites, while very tempting, are expensive and can be the mistake that kills a project or a company. Yet they are routinely proposed as the solution to all problems. Is there anything you can do to minimize the risk? In this post, I propose that you actively improve the old system to ensure the new system cannot make progress in a haphazard way. This forces the new system to be designed in such a way that delivers breakthrough improvements and not just incremental improvements.

January 24, 2020 · Tags: bazel, essay, featured, sre
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The OSXFUSE, hard links, and dladdr puzzle

Hello everyone and welcome to this new decade! It’s already 2020 and I’m only 17 days late in writing a first post. I was planning to start with an opinion article, but as its draft is taking longer than I wanted… I’ll present you the story of a recent crazy bug that has kept me busy for the last couple of days. Java crashes with Bazel and sandboxfs On a machine running macOS Catalina, install sandboxfs and build Bazel with sandboxfs enabled, like this:

January 17, 2020 · Tags: bazel, fuse, internals, programming
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Tree artifacts and transient files

To conclude the deep dive into Bazel’s dynamic spawn strategy, let’s look at the nightmare that tree artifacts have been with the local lock-free feature. And, yes, I’m double-posting today because I really want to finish these series before the end of the decade1! Tree artifacts are a fancy name for action outputs that are directories, not files. What’s special about them is that Bazel does not know a priori what the directory contents are: the rule behind the action just specifies that there will be a directory with files, and Bazel has to treat that as the unit of output from the action.

December 31, 2019 · Tags: bazel
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Lifting the local lock for dynamic execution

In the previous post, we saw how accounting for artifact download times makes the dynamic strategy live to its promise of delivering the best of local and remote build times. Or does it? If you think about it closely, that change made it so that builds that were purely local couldn’t be made worse by enabling the dynamic scheduler: the dynamic strategy would always favor the local branch of a spawn if the remote one took a long time.