Exception (Timeout trying to lock table ACT_RU_EXECUTION)

[lojian]

I am signal two process instance in 2 threads. But got following exceptions, any idea?

### The error may involve org.activiti.persistence.selectExecutionById-Inline
### The error occurred while setting parameters
### Cause: org.h2.jdbc.JdbcSQLException: Timeout trying to lock table "ACT_RU_EXECUTION" [50200-132]
   at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:8)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:61)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:53)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:38)
   at org.activiti.engine.impl.db.DbSqlSession.selectOne(DbSqlSession.java:175)
   at org.activiti.engine.impl.db.DbRuntimeSession.findExecutionById(DbRuntimeSession.java:89)
   at org.activiti.engine.impl.cmd.SignalCmd.execute(SignalCmd.java:42)
   at org.activiti.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:22)
   at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:37)
   at org.activiti.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
   at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
   at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
   at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:33)
   at org.activiti.engine.impl.RuntimeServiceImpl.signal(RuntimeServiceImpl.java:131)

[jbarrez]

I assume you are using H2, since it used by default table locking.

You could try to add MVCC=true to your url of H2.

[lojian]

Thanks….And yes, H2 is used…

After appended MVCC=true, the exception changes to:

[INFO] Exception in thread "taskExecutor-3" org.activiti.engine.ActivitiException: execution 29 doesn't exist
[INFO]  at org.activiti.engine.impl.cmd.SignalCmd.execute(SignalCmd.java:47)
[INFO]  at org.activiti.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:22)
[INFO]  at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:37)
[INFO]  at org.activiti.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:42)
[INFO]  at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
[INFO]  at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
[INFO]  at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:33)
[INFO]  at org.activiti.engine.impl.RuntimeServiceImpl.signal(RuntimeServiceImpl.java:131)

Any idea?

I am using Activiti 5.1

[jbarrez]

Do you get this exception on both machines?$

It looks like one thread is faster and signals the process for continuation.
The second thread can't signal it anymore, hence the exception, which is completely to be expected in the multi-threaded environment you have.

[lojian]

Do you mean I am signal 2 "identical" process instance?
:?:

[jbarrez]

Yes, looking at your exception it looks like you are signalling the same execution id.

[lojian]

Thank you for finding this for me 🙂

I see. There was a bug in my prototype program.