[OSM-dev] Reducing size on mediawiki server

[Robert (Jamie) Munro]

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Nick Hill wrote:
> Given we have trouble with services quitting on mediawiki, presumably through an 
> out of memory condition on the virtual server instance, anything we can do to 
> reduce the memory footprint of the services supporting the wiki should improve 
> reliability.
> 
> MySQL appears by far the hungriest service, so should get first attention.
> 
> According to top:
>    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>   1483 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.10 mysqld
>   1489 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.00 mysqld
>   1490 mysql     18   0 54032  24m 4992 S  0.0 10.7   0:00.00 mysqld
>   1491 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.00 mysqld
>   1492 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.01 mysqld
>   1493 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.01 mysqld
>   1502 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.00 mysqld
>   1503 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.00 mysqld
>   1506 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.01 mysqld
>   1568 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.05 mysqld
>   1573 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.87 mysqld
>   1817 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.26 mysqld
>   1898 mysql     15   0 54032  24m 4992 S  0.0 10.7   0:00.25 mysqld

This may be completely wrong or irrelevant, but I read somewhere that
disabling php's persistent connections can reduce the number of mysql
processes that are needed because the connections can be closed before
the php's output has been sent to the client. The overhead introduced by
the need to create a connection is usually very small if the database is
on the same machine as the php code.

Try disabling persistent connections in php.ini (or if they are
disabled, I suppose you could try enabling them :-) ).

Robert (Jamie) Munro


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