Expected one result (or null) to be returned by selectOne(), but found: 2

Ivgi · July 15, 2020, 8:46am

Hello,

Setup:
Camunda with tomcat - 9.0.12 (7.10) - as Windows Service
PostgreSql DB - 10.3
We use C# services with FetchAndLock Http requests

Yesterday after getting a few complaints about slow processing of documents.
I found a few errors in the Camunda logs and I was hoping you can shed some light on some of the possible reasoning behind it?

There were no notable changes that I am aware of which is why I am having hard times understanding why those errors started happening.

15-Jul-2020 00:02:30.031 SEVERE [pool-2-thread-3] org.camunda.commons.logging.BaseLogger.logError ENGINE-16004 Exception while closing command context: Expected one result (or null) to be returned by selectOne(), but found: 2
 org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:81)
	at org.camunda.bpm.engine.impl.db.sql.DbSqlSession.selectById(DbSqlSession.java:110)
	at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.selectById(DbEntityManager.java:212)
	at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:57)
	at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:39)
	at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:27)
	at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:106)
	at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:69)
	at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:50)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:43)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:91)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:60)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

15-Jul-2020 00:02:30.031 WARNING [pool-2-thread-3] org.camunda.commons.logging.BaseLogger.logWarn ENGINE-14006 Exception while executing job ab553cb2-cc9a-11e8-b815-005056be8350: 
 org.camunda.bpm.engine.ProcessEngineException: Process engine persistence exception
	at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.rethrow(CommandInvocationContext.java:150)
	at org.camunda.bpm.engine.impl.interceptor.CommandContext.close(CommandContext.java:177)
	at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:115)
	at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:69)
	at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:50)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:43)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:91)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:60)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:81)
	at org.camunda.bpm.engine.impl.db.sql.DbSqlSession.selectById(DbSqlSession.java:110)
	at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.selectById(DbEntityManager.java:212)
	at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:57)
	at org.camunda.bpm.engine.impl.cmd.ExecuteJobsCmd.execute(ExecuteJobsCmd.java:39)
	at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:27)
	at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:106)
	... 9 more

15-Jul-2020 00:02:30.046 SEVERE [pool-2-thread-3] org.camunda.commons.logging.BaseLogger.logError ENGINE-16004 Exception while closing command context: Process engine persistence exception
 org.camunda.bpm.engine.ProcessEngineException: Process engine persistence exception
	at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.rethrow(CommandInvocationContext.java:150)
	at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:117)
	at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:69)
	at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
	at org.camunda.bpm.engine.impl.jobexecutor.FailedJobListener.execute(FailedJobListener.java:54)
	at org.camunda.bpm.engine.impl.jobexecutor.FailedJobListener.execute(FailedJobListener.java:31)
	at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:27)
	at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:106)
	at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:69)
	at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.callFailedJobListenerWithRetries(ExecuteJobHelper.java:94)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.invokeJobListener(ExecuteJobHelper.java:75)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:63)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobHelper.executeJob(ExecuteJobHelper.java:43)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.executeJob(ExecuteJobsRunnable.java:91)
	at org.camunda.bpm.engine.impl.jobexecutor.ExecuteJobsRunnable.run(ExecuteJobsRunnable.java:60)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:81)
	at org.camunda.bpm.engine.impl.db.sql.DbSqlSession.selectOne(DbSqlSession.java:117)
	at org.camunda.bpm.engine.impl.db.entitymanager.DbEntityManager.selectOne(DbEntityManager.java:188)
	at org.camunda.bpm.engine.impl.persistence.entity.JobManager.findJobById(JobManager.java:164)
	at org.camunda.bpm.engine.impl.jobexecutor.FailedJobListener$1.execute(FailedJobListener.java:59)
	at org.camunda.bpm.engine.impl.jobexecutor.FailedJobListener$1.execute(FailedJobListener.java:54)
	at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:27)
	at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:106)
	... 17 more

Ivgi · August 25, 2020, 4:11pm

I now noticed that it is always the same Job Id which results in this error.
I read an older post about delete deployment issue with similar error but I aint using the delete operation.
After checking the logs It seems to be happening a few times every 4-5 minutes.
The logs are getting filled with those errors for the past month.
I am not sure what might have caused it.
But any hints about what sort of operation might be behind it can help!

like,
When does the Camunda engine uses JobManager.findJobById()?
What is the meaning of the JobId which I am getting in the logs?

Thank you in advance!

EDIT:

It seems that the ID I was talking about is from the table
act_ru_job

Indeed there are 2 rows with the same ID!
But I got no idea how such a thing can happen.
But I now know what it is related to. It is a job for cleaning history.