Re: 1023rd thread crashes 2.4.0-test8 from non-root user

From: Ted Deppner (ted@psyber.com)
Date: Mon Sep 25 2000 - 09:47:08 EST


On Mon, Sep 25, 2000 at 10:33:06AM +0200, Ingo Molnar wrote:
> On Mon, 25 Sep 2000, Ted Deppner wrote:
>
> > I ask because on my perl-threads test case, I can't create more than 1023
> > threads, but I get a kernel crash when I've _attempted_ to create more
> > than 1023 and hit ctrl-c.
>
> could you test this with the kernel/signal.c:max_queued_signals
> initialization change i suggested? Does it still crash?

With max_queued_signals=4096, I can still only create 1022 threads under
perl-5.005-threads.

With more than 1023 threads the process no longer responds to ctrl-c, or a
kill -INT on it. A kill -9 will kill it however with no kernel lockup.

Under 1023 threads the process responds to ctrl-c.

It seems like the bug is definately involved in signal handling, and that
max_queued_signals affects it in some way...

My ulimit -a from bash... you can see open files at 1024, but I'm not
doing open files stuff in my test program (threadcrash.pl).

core file size (blocks) 0
data seg size (kbytes) unlimited
file size (blocks) unlimited
max locked memory (kbytes) unlimited
max memory size (kbytes) unlimited
open files 1024
pipe size (512 bytes) 8
stack size (kbytes) 8192
cpu time (seconds) unlimited
max user processes 4093
virtual memory (kbytes) unlimited

I upped my open-files to 2048 and still was unable to get more than 1022
threads running. I wonder if perl-5.005-threads might have a static limit
set somewhere inside it. Maybe I'll try to recompile it tonight and see
what happens.

-- 
Ted Deppner
http://www.psyber.com/~ted/

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