Re: COND_WAIT in modperl_tipool

[Philippe M . Chiasson]

On 28-Mar-07, at 12:06 PM, Torsten Foertsch wrote:

Hi,


implementation but instead Perl's COND_... and MUTEX_... macros?

is there a reason not to use APR mutex and condition variables in the tipool

at that time or something.

But as far as I can tell, it doesn't really make much of a difference.

I know I wondered about that exact same thing a long time ago, and if memory serves me right, it was an early doug'ism. Think APR wasn't quite there yet

The reason I am asking is that after some heavy load generated with ab over a GBit link I have seen request timeouts and what is worse apache processes hanging around not accepting connections. Then I patched mod_perl/ mod_status to report the waiting in COND_WAIT via the scoreboard and saw there were some

requests hanging in this state after all traffic has been finished.


practically lowered by ThreadsPerChild.

The really bad thing about that is that the hanging process is alive for the master apache. So, it's share of the scoreboard is blocked and MaxClients is

showed you where this might be hapenning ?

That's strange, and could indicate some bug somewhere. Something not playing by the tipool's usage rules and causing these hangs. Any change your investigation

I have then changed the tipool implementation to use apr_thread_cond_timedwait with a timeout of 0.5 sec instead of COND_WAIT. The problem seems gone.

another one ;-)

Hrm, that sounds like you just worked around one problem, most likely causing

I know the problem lies probably not in mod_perl but in the pthread lib on my Linux (NPTL 2.5). But maybe it is saver programming not to wait forever. The

more as it is not determined in what order threads are awakened by a
pthread_cond_signal

code path was jamming.

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Philippe M. Chiasson     GPG: F9BFE0C2480E7680 1AE53631CB32A107 88C3A5A5
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Can you tell where these child were stuck in COND_WAIT ? I'm curious about what

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