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Problem 'Connection is invalid.' on Activiti DB

Question asked by timo.rohrberg on Aug 5, 2016
Latest reply on Aug 11, 2016 by timo.rohrberg
Hello everybody,

I'm addressing you guys today with a problem that we unfortunately cannot solve even though investigating and trying different configuration parameters to an unknow extent.

When setting our system internally using the Activiti workflow engine under heavy load, we get the error "Connection is invalid." in different situations when Activiti tries to query its database tables or even write updates to them. The error happens with different SQL statements executed by Activiti and depending on which one it is, the consequences are quite problematic. In some cases this can even lead to not starting a workflow when one should be started.

The stack trace always looks like this:
<java>
### Cause: java.sql.SQLException: Error accessing PooledConnection. Connection is invalid.
   at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:122)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113)
   at org.activiti.engine.impl.db.DbSqlSession.selectListWithRawParameter(DbSqlSession.java:443)
   at org.activiti.engine.impl.db.DbSqlSession.selectList(DbSqlSession.java:434)
   at org.activiti.engine.impl.db.DbSqlSession.selectList(DbSqlSession.java:429)
   at org.activiti.engine.impl.db.DbSqlSession.selectList(DbSqlSession.java:406)
   at org.activiti.engine.impl.persistence.entity.ExecutionEntityManager.findChildExecutionsByParentExecutionId(ExecutionEntityManager.java:113)
   at org.activiti.engine.impl.persistence.entity.ExecutionEntity.ensureExecutionsInitialized(ExecutionEntity.java:694)
   at org.activiti.engine.impl.persistence.entity.ExecutionEntity.createExecution(ExecutionEntity.java:272)
   at org.activiti.engine.impl.persistence.entity.ExecutionEntity.createExecution(ExecutionEntity.java:75)
   at org.activiti.engine.impl.pvm.runtime.AtomicOperationTransitionCreateScope.execute(AtomicOperationTransitionCreateScope.java:36)
   at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:97)
   at org.activiti.engine.impl.jobexecutor.AsyncContinuationJobHandler.execute(AsyncContinuationJobHandler.java:35)
   at org.activiti.engine.impl.persistence.entity.JobEntity.execute(JobEntity.java:85)
   at org.activiti.engine.impl.persistence.entity.MessageEntity.execute(MessageEntity.java:34)
   at org.activiti.engine.impl.cmd.ExecuteAsyncJobCmd.execute(ExecuteAsyncJobCmd.java:52)
   at org.activiti.engine.impl.interceptor.CommandInvoker.execute(CommandInvoker.java:24)
   at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:57)
   at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:37)
   at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:40)
   at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:35)
   at org.activiti.engine.impl.asyncexecutor.ExecuteAsyncRunnable.executeJob(ExecuteAsyncRunnable.java:95)
   at org.activiti.engine.impl.asyncexecutor.ExecuteAsyncRunnable.run(ExecuteAsyncRunnable.java:50)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
   at java.lang.Thread.run(Thread.java:745)
Caused by: java.sql.SQLException: Error accessing PooledConnection. Connection is invalid.
   at org.apache.ibatis.datasource.pooled.PooledConnection.checkConnection(PooledConnection.java:254)
   at org.apache.ibatis.datasource.pooled.PooledConnection.invoke(PooledConnection.java:243)
   at com.sun.proxy.$Proxy2.prepareStatement(Unknown Source)
   at sun.reflect.GeneratedMethodAccessor26.invoke(Unknown Source)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:483)
   at org.apache.ibatis.logging.jdbc.ConnectionLogger.invoke(ConnectionLogger.java:55)
   at com.sun.proxy.$Proxy2.prepareStatement(Unknown Source)
   at org.apache.ibatis.executor.statement.PreparedStatementHandler.instantiateStatement(PreparedStatementHandler.java:79)
   at org.apache.ibatis.executor.statement.BaseStatementHandler.prepare(BaseStatementHandler.java:88)
   at org.apache.ibatis.executor.statement.RoutingStatementHandler.prepare(RoutingStatementHandler.java:58)
   at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:76)
   at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:61)
   at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:303)
   at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:154)
   at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:102)
   at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:82)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120)
   … 25 common frames omitted
<java>

Our idea is that somehow the threads in the Activiti thread pool take to long to be executed and in the meantime MyBatis invalidates the DB connection. But increasing the parameter 'jdbcMaxCheckoutTime' completely blocks our system. We simply don't have any further idea how to approach this error.

Does anyone have an idea what can be the reason for that?

We appreciate any hint.

Regards
Timo

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