[EP-tech] Re: Eprints Server Freezes Often

Francis Jayakanth franc at ncsi.iisc.ernet.in
Tue May 22 07:43:14 BST 2012


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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