[EP-tech] New system, crashing periodically b/c MySQL Locking

[Fran Callaghan]

Hi Everybody,

We have a (reasonably) new install that has been grinding to a halt every
week or two. When I look at 'top' on the command line (Red Hat) mysqld is
hogging 100% CPU. When I use mysqladmin processlist I can see a number of
sessions queuing behind this...

| 104558 | doras | localhost | doras | Query   | 1587 |
statistics                   | INSERT INTO `cache17312`(`pos`, `eprintid`)
SELECT @i:=@i+1, `eprintid` FROM (SELECT `eprint`.`eprin | 0.000    |

The other processes (queued) are all waiting for table level lock and look
like this...


| 105134 | doras | localhost | doras | Query   | 487  | Waiting for table
level lock | UPDATE `eprint` SET `edit_lock_user`='1037',
`edit_lock_since`='1550139932', `edit_lock_until`='1550 | 0.000    |

| 105135 | doras | localhost | doras | Query   | 486  | Waiting for table
level lock | SELECT
`eprintid`,`rev_number`,`eprint_status`,`userid`,`importid`,`source`,`dir`,`datestamp_year`,`
| 0.000


Eventually the max http processes is reached and the system crashes. The
only remedy is to restart httpd and mariadb.


Any ideas what this insert into cache is and why it's locking the the
system?

Thanks for any guidance
Fran Callaghan
Dublin City University

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