[EP-tech] Re: Eprints Server Freezes Often

[yurj at alfa.it (Yuri)]

Lower the number of child and forked processes in apache config. The 
default config is usual for static pages. For example I've:

<IfModule mpm_prefork_module>
     StartServers          4
     MinSpareServers       2
     MaxSpareServers       8
     MaxClients           30
     MaxRequestsPerChild  1000
</IfModule>

It seems to work quite well. Also, I had to install mod_bw in apache to 
limit the max number of connection from the same ip, to calm down search 
engines and bots that download every pdf they find in the world... :-)

Il 19/05/2012 13:22, Francis Jayakanth ha scritto:
> Dear Members, Our eprints server freezes (stops responding) almost every
> week or so. The only solution to bring up the server again is to do a hard
> boot.
>
> I have looked into the Web Server error log file and find that around the
> time the system freezes, the following error is recorded in the error log
> file:
>
> [Thu May 18 06:10:05 2012] [error] (12)Cannot allocate memory: fork:
> Unable to fork new process
>
> So, the obvious reason for the system freeze is, the system is running
> out of main memory. Once the server is re-booted, everything is back to
> normal, but with the passage of time, the free memory keeps gradually
> dropping.
>
> The 'top' command issued right ofter the re-boot, gives the
> following output:
>
> top - 12:41:49 up 2 days, 55 min,  1 user,  load average: 0.90, 0.52, 0.35
> Tasks: 167 total,   1 running, 166 sleeping,   0 stopped,   0 zombie
> Cpu(s):  1.1%us,  0.2%sy,  0.0%ni, 97.3%id,  1.3%wa,  0.0%hi,  0.0%si,
> 0.0%st
> Mem:   4051536k total,  1162736k used,  2888800k free,    23300k buffers
> Swap:  8193108k total,   378836k used,  7814272k free,   438404k cached
>
> Over the period of few hours, the the usage of the main memory gradually
> goes up.
>
> The output of the 'top' command after 3 hours is:
>
> top - 15:42:07 up 2 days,  4:02,  1 user,  load average: 0.23, 0.22, 0.18
> Tasks: 173 total,   1 running, 172 sleeping,   0 stopped,   0 zombie
> Cpu(s):  0.0%us,  0.0%sy,  0.0%ni, 99.6%id,  0.4%wa,  0.0%hi,  0.0%si,
> 0.0%st
> Mem:   4051536k total,  3048740k used,  1002796k free,   129020k buffers
> Swap:  8193108k total,   378828k used,  7814280k free,   796732k cached
>
> For a time gap of 3 hours, the free memory size has come down from
> 2888800k to 1002796k. The drop will continue over the period of time and
> eventually, the system freezes.
>
> I restarted the apache server after about 3 hours and the output of the
> 'top' command is:
>
> top - 15:52:59 up 2 days,  4:07,  1 user,  load average: 0.11, 0.14, 0.16
> Tasks: 168 total,   1 running, 167 sleeping,   0 stopped,   0 zombie
> Cpu(s):  0.0%us,  0.0%sy,  0.0%ni, 99.6%id,  0.4%wa,  0.0%hi,  0.0%si,
> 0.0%st
> Mem:   4051536k total,  1686412k used,  2365124k free,   130712k buffers
> Swap:  8193108k total,   378820k used,  7814288k free,   801620k cached
>
> More than 1.3 GB of memory has been freed after restarting the apache
> server.
>
> How do I ensure that memory level doesn't gradually drop and eventually
> cause the server to freeze? Should something be done at the apache
> configuration level?
>
> Any help/pointers to overcome the said problem will of great help to us.
>
> We have recently upgraded our eprints software from eprints-3.2.8 to
> eprints-3.3.9. The above behaviour was very much there with the 3.2.8
> version as well.
>
> Apache Server version: Apache/2.2.3 on 64-bit RHES
>
> Many thanks in advance for your attention.
>
>
>    - Francis
>
> JRD Tata Memorial Library
> IISc, Bengaluru, India
>