Setting wsrep_desync=1 after FTWRL blocks a node
Affects | Status | Importance | Assigned to | Milestone | ||
---|---|---|---|---|---|---|
Percona XtraDB Cluster moved to https://jira.percona.com/projects/PXC | Status tracked in 5.6 | |||||
5.5 |
Won't Fix
|
Undecided
|
Unassigned | |||
5.6 |
Fix Released
|
High
|
Unassigned | |||
5.7 |
Fix Released
|
Undecided
|
Unassigned |
Bug Description
Tested the problem below on PXC 5.5.37, 5.6.20 and Maria Cluster 10.0.13.
percona33 mysql> flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)
-- err log on the same node:
2014-09-17 12:46:25 16422 [Note] WSREP: Provider paused at c3b203a1-
percona33 mysql> set global wsrep_desync=1;
... (waiting)
-- percona33 err log:
2014-09-17 12:47:35 16422 [Note] WSREP: Member 2.0 (percona33) desyncs itself from group
2014-09-17 12:47:35 16422 [Note] WSREP: Shifting SYNCED -> DONOR/DESYNCED (TO: 249)
-- remaining nodes err log:
2014-09-17 12:47:35 19275 [Note] WSREP: Member 2.0 (percona33) desyncs itself from group
-- second mysql session, opened before the test:
percona33 mysql> show processlist;
+----+-
| Id | User | Host | db | Command | Time | State | Info | Rows_sent | Rows_examined |
+----+-
| 1 | system user | | NULL | Sleep | 265 | NULL | NULL | 0 | 0 |
| 2 | system user | | NULL | Sleep | 265 | wsrep aborter idle | NULL | 0 | 0 |
| 3 | system user | | NULL | Sleep | 265 | NULL | NULL | 0 | 0 |
| 4 | root | localhost | NULL | Query | 74 | Opening tables | set global wsrep_desync=1 | 0 | 0 |
| 5 | root | localhost | NULL | Query | 0 | init | show processlist | 0 | 0 |
+----+-
5 rows in set (0.00 sec)
No new connections are accepted on percona33 node.
Ctrl+c in the session when desync mode was turned on does not work, also after killing it:
percona33 mysql> show processlist;
+----+-
| Id | User | Host | db | Command | Time | State | Info | Rows_sent | Rows_examined |
+----+-
| 1 | system user | | NULL | Sleep | 404 | NULL | NULL | 0 | 0 |
| 2 | system user | | NULL | Sleep | 404 | wsrep aborter idle | NULL | 0 | 0 |
| 3 | system user | | NULL | Sleep | 404 | NULL | NULL | 0 | 0 |
| 4 | root | localhost | NULL | Killed | 213 | Opening tables | set global wsrep_desync=1 | 0 | 0 |
| 5 | root | localhost | NULL | Query | 0 | init | show processlist | 0 | 0 |
+----+-
5 rows in set (0.00 sec)
The only way to unblock the node is to kill -9 mysqld.
Corresponding bug filled at: /github. com/codership/ galera/ issues/ 131
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