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[EP-tech] Re: Eprints Server Freezes Often

On Mon, 21 May 2012, Yuri wrote:


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... :-)
Thanks, Yuri, for the suggestions. I have incorporated the above changes in the apache config file. Keeping a watch on the web server behaviour. Will let the list know if the changes made to the apache config file is helping us or not.
Also, I have noticed that the following error message has been reported quite often in the web server error log file: 

-----------------EPrints System Error ----------------------------
Error connecting to MySQL server: Too many connections. To fix this increase max_connections in my.cnf: 

[mysqld]
max_connections=300

------------------------------------------------------------------
Should I incorporate the above 'mysqld' directive or will the changes made in the apache config take care of the MySQL error? 

Thanks once again.

 - Francis

JRDTML, IISc
Bengaluru, India

eprints.iisc.ernet.in



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



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