On Sunday 26 February 2012 19.59.07 Tomas Vondra wrote:
i.e. about 200 MB of free memory, but apache fails because of segfaults
when forking a child process:

[16:49:51 2012] [error] (12)Cannot allocate memory: fork: Unable to
fork new process
[16:51:17 2012] [notice] child pid 2577 exit signal Segmentation
fault (11)
In general things can get quite bad with relatively high memory pressure and
no swap.

That said, one thing that comes to mind is stacksize. When forking the linux
kernel needs whatever the current stacksize is to be available as (free + free

Also, just because you see Y bytes free doesn't mean you can successfully
malloc that much (fragmentation, memory zones, etc.).

or when processing requests:

[26 16:30:16 2012] [error] [client] PHP Fatal error: Out
of memory (allocated 262144) (tried to allocate 523800 bytes) in
Unknown on line 0

The memory_limit in PHP is set to 32MB, so it's not the case. Similar
issues happen to PostgreSQL:

16:42:01 CET pid%04 db=xxxxxx-drupal user=xxxxxx FATAL: out of
16:42:01 CET pid%04 db=xxxxxx-drupal user=xxxxxx DETAIL: Failed on
request of size 2488.
16:42:01 CET pid$38 db= user= LOG: could not fork new process for
connection: Nelze alokovat pam??
16:42:01 CET pid$38 db= user= 4f4a5247.986:21 LOG: could not fork
new process for connection: cannot allocate memory

I have absolutely no clue what's causing this / how to fix it. According
to free/vmstat there's about 200MB of free RAM all the time, so I have
no idea why the alloc calls fail.
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postedFeb 26, '12 at 1:59p
activeFeb 28, '12 at 5:01p

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Tomas Vondra: 3 posts Peter Kjellström: 1 post



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