Workflow execution failure with MariaDB 10.x release

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 with camunda release 7.7.0 and Maria DB 10.x
And it is working with camunda 7.8.0 / 7.9.0 release with h2 database.

But it is not working with camunda 7.8.0 / 7.9.0 and Maria DB 10.x.

The problem is started from 7.8.0-alpha6 release onwards. Till 7.8.0-alpha5 release all are working fine.

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 ;;