From: "Ludovic Courtès" <ludo@gnu.org>
To: ericbavier@centurylink.net
Cc: 37510@debbugs.gnu.org, Eric Bavier <bavier@member.fsf.org>
Subject: [bug#37510] [PATCH 1/1] compile: Fix race condition on completion progress.
Date: Thu, 26 Sep 2019 11:28:28 +0200 [thread overview]
Message-ID: <87pnjnpfsz.fsf@gnu.org> (raw)
In-Reply-To: <20190925020706.6034-1-ericbavier@centurylink.net> (ericbavier@centurylink.net's message of "Tue, 24 Sep 2019 21:07:06 -0500")
Hello,
ericbavier@centurylink.net skribis:
> From: Eric Bavier <bavier@member.fsf.org>
>
> This prevent a race condition where multiple compilation threads could report
> the same completion.
>
> * guix/build/compile.scm (compile-files)<completed>: Increment in same mutex
> region as the compilation is reported.
>
>
> Further reading:
>
> When compiling many scheme files, or with '-j1', this is not usually a
> problem, but with multiple build jobs and a handful of scheme files to update,
> you may encounter unexpected output. E.g. I recently saw this from `make -j2`:
>
> ```
> Compiling Scheme modules...
> [ 25%] LOAD gnu/packages/haskell.scm
> ;;; note: source file ./gnu/packages/haskell.scm
> ;;; newer than compiled /home/bavier/projects/guix/gnu/packages/haskell.go
> ;;; note: source file ./gnu/packages/haskell.scm
> ;;; newer than compiled /home/bavier/projects/guix/gnu/packages/haskell.go
> [ 50%] LOAD gnu/packages/idris.scm
> ;;; note: source file ./gnu/packages/idris.scm
> ;;; newer than compiled /home/bavier/projects/guix/gnu/packages/idris.go
> ;;; note: source file ./gnu/packages/idris.scm
> ;;; newer than compiled /home/bavier/projects/guix/gnu/packages/idris.go
> [ 75%] GUILEC gnu/packages/haskell.go
> [ 75%] GUILEC gnu/packages/idris.go
I think it’s expected: it shows completion at the time we started to
build these files. Compilation of haskell.scm and idris.scm started at
the same time, and at that point we had built 75% of the files. I agree
it’s confusing though. :-)
> +++ b/guix/build/compile.scm
> @@ -173,7 +173,8 @@ files are for HOST, a GNU triplet such as \"x86_64-linux-gnu\"."
>
> (define (build file)
> (with-mutex progress-lock
> - (report-compilation file total completed))
> + (report-compilation file total completed)
> + (set! completed (+ 1 completed)))
Here ‘completed’ is incremented before the thing is even started.
Anyway, LGTM! :-)
Ludo’.
next prev parent reply other threads:[~2019-09-26 9:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 2:07 [bug#37510] [PATCH 1/1] compile: Fix race condition on completion progress ericbavier
2019-09-26 9:28 ` Ludovic Courtès [this message]
2019-09-26 13:42 ` Eric Bavier
2019-09-26 20:57 ` Ludovic Courtès
2019-09-28 4:01 ` bug#37510: " Eric Bavier
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