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Re: fork/exec for hooks scripts with a large FSFS cache

From: Peter Samuelson <peter_at_p12n.org>
Date: Thu, 15 Nov 2012 09:28:59 -0600

[Philip Martin]
> If I configure a server with an FSFS cache that uses about 50% of
> available memory and then I use the server so the cache is in use I
> find that hook scripts fail to run because the fork/exec cannot
> allocate memory.

You didn't say what OS this is. It matters. Some are configured to
overcommit RAM allocation, because a lot of software tends to allocate
far more RAM than it actually needs. (fork() is only one case of
this.)

The other reason the OS matters is that some OSes support a vfork()
call which would avoid this issue entirely. Unfortunatley it seems
apr_proc_create() has no option to use vfork() instead of fork(), even
for OSes (Linux and most Unixes) that support it.

Peter
Received on 2012-11-15 16:29:43 CET

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