[rt-users] Can't fork at Mailer.pm

[Tim Cutts]

On 8 Oct 2012, at 09:42, Martin Drasar <drasar at ics.muni.cz> wrote:

> On 5.10.2012 19:05, Thomas Sibley wrote:
>> On 10/05/2012 02:31 AM, Martin Drasar wrote:
>>> after upgrading to RT 4.0.6 I am having problems with mail sending. This
>>> line starts to appear in log:
>>> 
>>> Scrip Commit 6 died. - Can't fork at /usr/share/perl5/Mail/Mailer.pm
>>> line 145
>>> 
>>> and no mail can be sent until I restart the Apache.
>>> 
>>> Do you have any idea why it is happening? And more importantly - how can
>>> I solve this so it does not happen again?
>> 
>> Can't fork means your operating system is dangerously out of memory.
>> You should tune Apache and anything else on the box (your database
>> server?) to coexist peacefully.
>> 
>> What MailCommand are you using in RT?
> 
> Hi Thomas,
> 
> I am using sendmail as a mail command, but you are most likely right
> about insufficient memory. I have checked the logs and Apache processes
> were dying of memory starvation. I have doubled the memory (it was only
> 1 gig) and will check if it keeps happening.

Make sure you have plenty of swap allocated; you may not need the memory as physical.  I run the RT web server on a machine with only 2GB of RAM, and it's fine.  I don't run the database on the same machine, though.  You have to remember that when Apache/perl forks to exec the sendmail binary, temporarily you double the virtual memory requirement of the Apache/perl setup.  You either have to have virtual memory overcommit turned on (which I think is the default on most Linux systems these days) or to have enough swap allocated to cope.  

vm.overcommit_memory = 0

in /etc/sysctl.conf is probably what you want.  You probably actively don't want it to be set to 2.

Tim

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