Re: threads & /proc

[FORT David <popo.enlighted@free.fr>]

Peter Zaitsev wrote:

>Hello Anton,
>
>Saturday, November 24, 2001, 8:38:57 AM, you wrote:
>
>
>I would confirm the problem exists from the first 2.4.x kernels. Also
>programs "w","vmstat","snmpd" hangs.  It seems to happen both for
>UP/SMP kernels. I have seen this only on High Memory (1-2G), therefore
>I do not have much low memory machines loaded.  The workload seems to
>be the thing to affect this - I do not remember any hang on low VM
>load system (for example Web Server) therefore it's offen happens
>then there are a lot of I/O  and swapping goes (i.e Mysql Server).
>Often this happens after appearing some of new __order allocation
>failed errors.
>
>
>
>
>Other issue which looks like connected to this - a thread hangs in
>"D" state forever and it's unable to be killed in this case even
>reboot -f does not work.
>
>AP> Hi Guys,
>
>AP> Well, I'm a bit surprised that nobody asked it yet. Do we have sound
>AP> thread support? I am able to put my linux-2.4.15-pre{1,7} --
>AP> definitely, and if I remember right, 2.4.14-pre{7,8} too in some strange
>AP> state, when any program like top, killall or ps that wanna get some
>AP> information from /proc (even midnight commander if you are trying to
>AP> look at state of any process) blocks indefinitely. It goes to unclean
>AP> shutdown, for example. kill doesn block, but do nothing. (I tried to
>AP> kill processes from ls /proc list). And I see it only after several
>AP> [unsuccessful] runs of my multithreaded program. Well, I can't say 
>AP> it's a correctly written program, I am still looking for bugs there. 
>AP> I don't have 100% way to get into this state, but I suspect some locking
>AP> issues with /proc. 
>
>
>
I've also seen the case on a UP, ps was locking. And i had launched a
lot of multi-threaded processes(but i don't know if it's related).
I can had that i had also launched a lot of gdb on the multi-threaded
program. The program i was debugging is forking a process in a thread
that dies after the fork.

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