Subject: bug#35139: Rust builds systematically time out

From: Ivan Petkov <[email-masked]>
Date: Thu, 4 Apr 2019 10:37:03 -0700

Danny’s got a patch for turning on parallel tests in #35126

Not sure why the previous tests were running sequentially, but there is a comment somewhere saying it’s to avoid EAGAIN errors.

--Ivan

> On Apr 4, 2019, at 9:06 AM, Ludovic Courtès <[email-masked]> wrote:
> 
> Ivan Petkov <[email-masked]> skribis:
> 
>>> On Apr 4, 2019, at 1:59 AM, Ludovic Courtès <[email-masked]> wrote:
>>> 
>>> The build nodes may be slower than the front-end, but still, it seems
>>> unlikely that it would take more than 6h there.  (That could happen if
>>> the test suite, which lasts 2.1h, were “embarrassingly parallel”, but
>>> we’re running tests with ‘-j1’.)
>>> 
>>> To summarize, there are two problems:
>>> 
>>> 1. Rust takes too long to build.  What can we do about it?  Enable
>>>    parallel builds?
>> 
>> Rust tests are designed to run in parallel, as long as you have enough
>> RAM, file descriptors, etc. available on the machine for the amount of
>> concurrency being used. The compiler test suite is largely just compiling
>> files, so the most important resource is probably available RAM/swap.
> 
> Perhaps we could start with:
> 
>  "-j" (number->string (min (parallel-job-count) 2))
> 
> ?
> 
>> Maybe if the bootstrapped versions don’t ever change skipping the check
>> phase will be safe, but I think we should try running parallel tests first
>> and see how far that gets us.
> 
> Sounds like a good start.
> 
> So the only reason we’re running tests sequentially is because of memory
> usage concerns?
> 
> Thanks,
> Ludo’.