MySQL Bugs: #87652: InnoDB: Warning: a long semaphore wait:

Bug #87652	InnoDB: Warning: a long semaphore wait:
Submitted:	4 Sep 2017 9:35	Modified:	4 Sep 2017 19:40
Reporter:	Dominik Müller	Email Updates:
Status:	Can't repeat	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S1 (Critical)
Version:	mysql Ver 14.14 Distrib 5.5.57, for deb	OS:	Debian (Jessie)
Assigned to:	MySQL Verification Team	CPU Architecture:	Any
Tags:	innodb semaphore crashs

Description:
This Error happens every few days. It is a shared hosting Server with only about 15 customers on it. The Databases that lead to this error seems to be owncloud/nextcloud-Installations.

The error leads to a crash of mysql, and a long restart time when it is manually (or automatically by monitoring) restarted. In meanwhile the mysql-service is not usable, not reachable.

How to repeat:
not known, it just happens on this one system (I have running several systems with same configuration and even much more customers)

Hi,

There is no crash in the log you provided, only a shutdown/restart and bunch of errors accessing disk during startup.. probably your startup scripts are not ok but since this does not look like mysql binary those scripts are also not provided by us but probably by your distro.

InnoDB monitor log does show congestion but this does not look like a bug but a problem with storage subsystem (maybe that shared hosting has slow disks?, low iops capacity?), in any way this is something you can sort out with our Support team and properly configure your system, I don't see a bug here.

best regards
Bogdan