More data on 7.2-RELEASE "hangs"

[Steven Hartland]

----- Original Message ----- 
From: "Marc G. Fournier" <scrappy at hub.org>

> Right now, IO is running ~775 processes ... at the time of the vmstat I 
> provided earlier, it was up to 1400 processes ... since there is only 5 
> minutes between script runs, something is causing it to go from zero swap 
> -> high swap within a very short period of time, but since things get 
> badly locked up when it happens, I can't isolate where ...

We've seen things similar to this when an process uncommon process does
a query which locks the a table for a large amount of time on mysql.

In our example this turned out to be an admin query in vbulletin. When
it happened it turned a machine which was purring along quite nicely
into a totally unresponsive machine in a matter of a few seconds as
apache spawned more process that also then instantly stalled...

So its likely the overloaded diagnosis could well be correct, but as
you say it hard to diagnose with the machine in such an unusable state.

Reducing max handlers etc on apache will help with this prevent the
machine becoming unusable and hence give you time and resources to
determine what the real issue is.

    Regards
    Steve

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