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Re: maintainer mode parallel make issue
From: |
Ralf Wildenhues |
Subject: |
Re: maintainer mode parallel make issue |
Date: |
Mon, 20 Apr 2009 22:11:12 +0200 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
Hi Eric,
* Eric Blake wrote on Mon, Apr 20, 2009 at 06:44:17PM CEST:
> Ralf Wildenhues <Ralf.Wildenhues <at> gmx.de> writes:
>
> > You can try this; test against git next of Automake.
> > However, it also causes a hang on Cygwin, so there may be an independent
> > bug (in the test or in perl); the lock() called from the thread seems to
> > never complete.
>
> Hmm. On some systems flock(2) is documented as being per-process only (that
> is, you can't lock a file from yourself in a multi-threaded app[1]).
Oh. I didn't know that. My test was a rather quick hack anyway, good
to have a good reason now not to commit it.
> I'm not
> sure if flockfile(3) (at the FILE*) level, or fcntl(2)/lockf() at the fd
> level,
> do any better, but that doesn't matter since perl's flock states that whether
> it was implemented with flock or fcntl depends on how perl was configured.
It doesn't really matter: nothing within Automake requires file locking
at the perl threads level. Well, it may matter for the implementation
issues that the Cygwin developers work on.
> Therefore, is this test even valid, since you did it via perl threads as
> opposed to independent processes?
Likely not.
> But the point remains that we DO want perl's
> flock to work for cross-process locking (automake and autoconf both need a
> lock
> on autom4te.cache/requests, to block whichever task starts late).
Yes, definitely. And a testsuite addition to Autoconf or Automake to
ensure this would be good, I guess.
Thanks for doing the research!
Cheers,
Ralf
- maintainer mode parallel make issue, Eric Blake, 2009/04/16
- Re: maintainer mode parallel make issue, Ralf Wildenhues, 2009/04/16
- Re: maintainer mode parallel make issue, Eric Blake, 2009/04/16
- Re: maintainer mode parallel make issue, Eric Blake, 2009/04/16
- Re: maintainer mode parallel make issue, Ralf Wildenhues, 2009/04/16
- Re: maintainer mode parallel make issue, Ralf Wildenhues, 2009/04/18
- Re: maintainer mode parallel make issue, Eric Blake, 2009/04/18
- Re: maintainer mode parallel make issue, Ralf Wildenhues, 2009/04/19
- Re: maintainer mode parallel make issue, Eric Blake, 2009/04/20
- Re: maintainer mode parallel make issue,
Ralf Wildenhues <=
- Re: maintainer mode parallel make issue, Ralf Wildenhues, 2009/04/22
- Re: maintainer mode parallel make issue, Eric Blake, 2009/04/16
- Re: maintainer mode parallel make issue, Eric Blake, 2009/04/16