[ILUG] Return of the 'Unable to fork' monster

[Tony Bolger]

Paul Jakma wrote:
> 
> On Thu, 16 Mar 2000, Tony Bolger wrote:
> 
> > One of my rather overspeced linux servers had an attack of the old
> > 'Unable to fork' problem on Sunday. Normally, this would be annoying
> > enough, but on a server with 400MB of free RAM, its just not on. 
> did the log say why it was unable to fork? i doubt it's due to 
> swap/ram. 

Inetd created lots of entries like:

Mar 14 14:12:09 turboapps inetd[1042]: fork: Cannot allocate memory

And Apache:

[Tue Mar 14 14:15:26 2000] [error] [client 192.168.26.10] (12)Cannot
allocate memory: couldn't spawn child process:
/home/httpd/cgi-bin/ssirand.cgi 

It eventually got to the stage that shell programs gave unable to fork
errors too. 

And it looks like the sunday reboot didn't keep it happy long, since its
complaining again :(  

>More likely you've hit a resource limit like file descriptors or number
> of processes. both of which can be tweaked via /proc/sys/kernel.

That also seems to be a problem. It occasionally complained about
max_files reached. 

> see src/linux/Documentation/sysctl/kernel.txt or something
> similar.
> 
> What kind of use does your box get?

Not much, maybe 20 concurrent apache connections. Delivers about 25000
emails a day on maillists. A fair few pop connections, maybe 10 a
minute. Same of SMTP. And a little FTP use. Nothing much. Load average
in the range 0.2-0.4

	Tony.