MariaDB Galera Cluster Table locking issue after mysqldump execution

Description

We updated MariaDB Galera Version to 5.5.41 on 19th of January.
We start a daily mysqldump on 21:00 CET. This worked for ~ 1 year without any issues.
Last night (18th of FEB), the following issue happend at 21:00 (9 p.m.):

  • mysqldump starts on Node 1 with the following parameters:
    mysqldump -uroot -p --create-options {DATABASE_NAME} -f

  • simultaneously, the following query did not complete on Node 1 and remains with the state "sql end" on the server:
    INSERT INTO `{DBNAME}`.`{TABLE_NAME}` (isin, date, count )\n VALUES ('XXXX12345', CURDATE() , 1 )\n ON DUPLICATE KEY UPDATE count=count+1

  • full mysqldump on Node 1 completed with a duration of only a minute without any issues like every day, dumps are valid and complete

  • new incoming connections on Node 1 try to access the same table, but are waiting in state "Waiting for table level lock"
    INSERT INTO `{DBNAME}`.`{TABLE_NAME}` (isin, date, count )\n VALUES ('YYYY67890', CURDATE() , 1 )\n ON DUPLICATE KEY UPDATE count=count+1

  • INSERT/UPDATE statements on the same table on Node 2/3 do also not complete. Sessions are haning with similar statements in states "update" and "query end", first sessions appeared on 21:00

  • Number of connections increases on all 3 nodes, since all nodes are waiting for first INSERT statement on Node 1 to complete, therefore replication stopped.

  • Nodes 2 and 3 ran out of free connections and resources at ~ 21:10

  • INSERT statement on Node 1 could not be killed, whole Cluster needed to be shut down and restarted

  • Errorlogs do not show any issues until the high amount of connections leads to service unavailability

  • Nodes did not write any Core Dumps

  • This Incident is (hopefully) not reproducable, as already mentioned the cluster ran wihtout any issues about a year, the mysqldump is made every day at the same time.

Environment

CentOS release 6.5 2.6.32-431.3.1.el6.x86_64
VM, 4GB RAM
MariaDB Galera Cluster consists of 3 nodes

Status

Assignee

Nirbhay Choubey

Reporter

Tobias Kleinke

External issue ID

None

External issue ID

None

Time tracking

2h

Components

Affects versions

5.5.41-galera

Priority

Critical