I figured it out. The problem was somewhere else completely - with
python itself. I copied the patches from the FreeBSD port of python,
and so far it is looking good.
On 04/21/2012 05:20 PM, Volker Braun wrote:
I guess the os.wait() throws an OSError with errno = EINTR because the
SIGALARM fires? If that is the case we should probably ignore it in
use_fork.py
On Saturday, April 21, 2012 3:36:44 PM UTC-4, Stephen Montgomery-Smith
wrote:
I did some research, and I found that you are completely correct. I
don't know why FreeBSD is misbehaving, because the os.wait command
definitely triggers the OSError exception. signal.getsignal(SIGCHLD)
shows that it is correctly set to signal.SIG_DFL. So I am mystified.
Thank you for setting me straight.
On 04/21/2012 08:58 AM, Volker Braun wrote:
> I don't have a FreeBSD box to try this on, but note that children
> shouldn't just disappear when they finish. They remain as zombies
> (<defunct> in ps) until they are collected by os.wait()
>
>
>
> On Saturday, April 21, 2012 12:39:13 AM UTC-4, Stephen
Montgomery-Smith
> wrote:
>
> In parallel/use_fork.py, around line 120, there seems to be a race
> problem. This seems to be a genuine problem with my FreeBSD build:
> sage -t -force_lib "devel/sage/sage/parallel/decorate.py"
> goes into a permanent loop.
>
> Suppose that timeout has been set, and the forked process is too
slow.
> So then SIGALRM is sent by the alarm before the "os.wait()[0]" is
> completed. But now suppose that after the alarm has triggered, the
> forked process manages to finish before getting to the
"os.kill(pid,9)"
> command. Then "len(workers)" is still positive, so the while loop
> continues. But now the "os.wait()[0]" command has nothing to wait for
> (since it should be waiting for "pid" to die), and everything ends up
> stalling.
>
> Also if you do an os.kill command on a non-existent pid, you get an
> OSError.
>
> I really don't understand the full logic of this code, otherwise I
> would
> give you guys a patch.
>
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