Hi Yana,
All workflows are getting failed with the error - Optimistic Locking exception when integrating camunda engine with MariaDB 10.x release. Any sequential / parallel execution is failing.
Error during workflow execution :
An error happened while submitting the task form :
Cannot submit task form 8190f28c-6eeb-11e8-b622-fa163e5b9340: ENGINE-03005 Execution of ‘UPDATE ExecutionEntity[818ea893-6eeb-11e8-b622-fa163e5b9340]’ failed. Entity was updated by another transaction concurrently.
It is throwing optimistic locking Exception.
The same workflow is working fine till camunda release 7.8.0-alpha5 with Maria DB 10.x
And it is working fine with camunda 7.8.0 / 7.9.0 release and h2 database.
But it is not working from camunda 7.8.0-alpha6 release and Maria DB 10.x.
I have created a bug
https://app.camunda.com/jira/browse/CAM-9145
I have done a basic debugging with Camunda 7.9.0 engine.
The below statement returns the updateCount as “-2”. The update count should be “1” for avoiding optimistic locking exception.
flushResult = persistenceSession.flushOperations();
Method – protected void flushDbOperations(List operationsToFlush)
File – org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager
Really it is a blocking issue.
Transaction Log shows there is a try to apply the lock on ACT_GE_PROPERTY twice
2 lock struct(s), heap size 1136, 1 row lock(s), undo log entries 1
MySQL thread id 3508, OS thread handle 140480266315520, query id 56760 demo cleaning up
Trx read view will not see trx with id >= 10270, sees < 10269
TABLE LOCK table db03
.ACT_GE_PROPERTY
trx id 10270 lock mode IX
RECORD LOCKS space id 224 page no 3 n bits 80 index PRIMARY of table db03
.ACT_GE_PROPERTY
trx id 10270 lock_mode X locks rec but not gap
Record lock, heap no 14 PHYSICAL RECORD: n_fields 5; compact format; info bits 0
0: len 9; hex 6e6578742e64626964; asc next.dbid;;
1: len 6; hex 00000000281e; asc ( ;;
2: len 7; hex 4e0000021628f0; asc N ( ;;
3: len 3; hex 323031; asc 201;;
4: len 4; hex 80000003; asc ;;
—TRANSACTION 10269, ACTIVE 2328 sec
2 lock struct(s), heap size 1136, 1 row lock(s)
MySQL thread id 3504, OS thread handle 140481065899776, query id 56744 demo cleaning up
TABLE LOCK table db03
.ACT_GE_PROPERTY
trx id 10269 lock mode IX
RECORD LOCKS space id 224 page no 3 n bits 80 index PRIMARY of table db03
.ACT_GE_PROPERTY
trx id 10269 lock_mode X locks rec but not gap
Record lock, heap no 5 PHYSICAL RECORD: n_fields 5; compact format; info bits 0
0: len 15; hex 6465706c6f796d656e742e6c6f636b; asc deployment.lock;;
1: len 6; hex 000000001f17; asc ;;
2: len 7; hex f6000001dd0150; asc P;;
3: len 1; hex 30; asc 0;;
4: len 4; hex 80000001; asc ;;