Thread:Project:Support desk/Memory Leak? Memory running out./reply

mysqld is the Mysql database server, not MediaWiki (MediaWiki is handled by php and your webserver). You may need to configure mysql server properly according to your available memory.

Note that databse servers usually need to consume more memory to buffer query results and data that's accessed more frequently, so retrieving that data doesn't require to fetch it from the disk (which would be slow). Reducing the available memory for the database may make database access slower.