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    <title>topic NPE on engine.getTaskService().createTaskQuery() in Alfresco Archive</title>
    <link>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206973#M160103</link>
    <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;SPAN&gt;NPE on engine.getTaskService().createTaskQuery()&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;Hi,&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;We are experiencing a NPE on making this activity query call:&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;engine.getTaskService().createTaskQuery().taskId(taskId).includeProcessVariables().singleResult();&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;This only happens very occasionally and we have not found a way to reproduce the error. Nether occasion has been during any heavy load though both occasions have been at the same point in the BPMN where two parallel flows are executing a task each before entering an inclusive gateway. What we see is this error on the first task:&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;### Error querying database.&amp;nbsp; Cause: java.lang.NullPointerException&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;### Cause: java.lang.NullPointerException&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;org.apache.ibatis.exceptions.PersistenceException: &lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;### Error querying database.&amp;nbsp; Cause: java.lang.NullPointerException&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;### Cause: java.lang.NullPointerException&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:23) ~[mybatis-3.2.5.jar:3.2.5]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:107) ~[mybatis-3.2.5.jar:3.2.5]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:98) ~[mybatis-3.2.5.jar:3.2.5]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.db.DbSqlSession.selectListWithRawParameterWithoutFilter(DbSqlSession.java:426) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.persistence.entity.TaskEntityManager.findTasksAndVariablesByQueryCriteria(TaskEntityManager.java:139) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.TaskQueryImpl.executeList(TaskQueryImpl.java:930) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.AbstractQuery.executeSingleResult(AbstractQuery.java:158) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.AbstractQuery.execute(AbstractQuery.java:141) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.interceptor.CommandInvoker.execute(CommandInvoker.java:24) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:57) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:47) ~[activiti-spring-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:133) ~[spring-tx-4.1.3.RELEASE.jar:4.1.3.RELEASE]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:45) ~[activiti-spring-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:31) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:40) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:35) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; at org.activiti.engine.impl.AbstractQuery.singleResult(AbstractQuery.java:104) ~[activiti-engine-5.16.1.jar:5.16.1]&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;and 1/10th of a second later the other task correctly makes this query call and continues on while the first leg is left in as stalled state and never reaches the gateway.&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;We have looked at past forum posts and note that it seems very similar to an old bug fixed in version 5.13 (while we are on a much later version 5.17) : &lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;A href="https://forums.activiti.org/content/npe-variables-get-processinstance-loaded-processinstancequery" rel="nofollow noopener noreferrer"&gt;https://forums.activiti.org/content/npe-variables-get-processinstance-loaded-processinstancequery&lt;/A&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;That particular bug raised was on a createProcessInstanceQuery() while we are using a taskQuery. Is it possible the bug was fixed only for processInstance queries? (The old link to the fix is no longer available).&lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;Can you shed any light on what this issue might be and why it could be happening so infrequently? &lt;/SPAN&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;For now it seems that our only workaround is a crude one - wrapping this call in a try/catch, waiting and then retrying a specific number of times before failing&lt;/SPAN&gt;&lt;BR /&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
    <pubDate>Tue, 03 Nov 2015 15:21:17 GMT</pubDate>
    <dc:creator>markvt</dc:creator>
    <dc:date>2015-11-03T15:21:17Z</dc:date>
    <item>
      <title>NPE on engine.getTaskService().createTaskQuery()</title>
      <link>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206973#M160103</link>
      <description>NPE on engine.getTaskService().createTaskQuery()Hi,We are experiencing a NPE on making this activity query call:engine.getTaskService().createTaskQuery().taskId(taskId).includeProcessVariables().singleResult();This only happens very occasionally and we have not found a way to reproduce the error. Ne</description>
      <pubDate>Tue, 03 Nov 2015 15:21:17 GMT</pubDate>
      <guid>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206973#M160103</guid>
      <dc:creator>markvt</dc:creator>
      <dc:date>2015-11-03T15:21:17Z</dc:date>
    </item>
    <item>
      <title>Re: NPE on engine.getTaskService().createTaskQuery()</title>
      <link>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206974#M160104</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;SPAN&gt;Just a quick answer for now if you want to continue pursuing it:&lt;/SPAN&gt;&lt;BR /&gt;&lt;SPAN&gt;The link from the other forum post was incorrect due to a trailing "." follow this link to see the commit&lt;/SPAN&gt;&lt;BR /&gt;&lt;A href="https://github.com/Activiti/Activiti/commit/136859b6e4100d80c34bfc5c43964c8c8e4362de" rel="nofollow noopener noreferrer"&gt;https://github.com/Activiti/Activiti/commit/136859b6e4100d80c34bfc5c43964c8c8e4362de&lt;/A&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Wed, 04 Nov 2015 06:56:20 GMT</pubDate>
      <guid>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206974#M160104</guid>
      <dc:creator>erikwinlof</dc:creator>
      <dc:date>2015-11-04T06:56:20Z</dc:date>
    </item>
    <item>
      <title>Re: NPE on engine.getTaskService().createTaskQuery()</title>
      <link>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206975#M160105</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;SPAN&gt;Since this very much sounds like a bug, please file it in github instead and lets continue the conversation there:&lt;/SPAN&gt;&lt;BR /&gt;&lt;A href="https://github.com/Activiti/Activiti/issues" rel="nofollow noopener noreferrer"&gt;https://github.com/Activiti/Activiti/issues&lt;/A&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;SPAN&gt;..also supply your process so it can be reproduced (I understand it doesn't happen every time but having a unit test that sometimes reproduces it is better than nothing), see link below for a starting point to easily create a unit test for Activiti with a process definition:&lt;/SPAN&gt;&lt;BR /&gt;&lt;A href="https://github.com/Activiti/Activiti/tree/master/tooling/archetypes/activiti-archetype-unittest" rel="nofollow noopener noreferrer"&gt;https://github.com/Activiti/Activiti/tree/master/tooling/archetypes/activiti-archetype-unittest&lt;/A&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Wed, 04 Nov 2015 07:05:13 GMT</pubDate>
      <guid>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206975#M160105</guid>
      <dc:creator>erikwinlof</dc:creator>
      <dc:date>2015-11-04T07:05:13Z</dc:date>
    </item>
    <item>
      <title>Re: NPE on engine.getTaskService().createTaskQuery()</title>
      <link>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206976#M160106</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;SPAN&gt;Thanks - Moved here: &lt;/SPAN&gt;&lt;A href="https://github.com/Activiti/Activiti/issues/715" rel="nofollow noopener noreferrer"&gt;https://github.com/Activiti/Activiti/issues/715&lt;/A&gt;&lt;BR /&gt;&lt;BR /&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Wed, 04 Nov 2015 09:41:16 GMT</pubDate>
      <guid>https://connect.hyland.com/t5/alfresco-archive/npe-on-engine-gettaskservice-createtaskquery/m-p/206976#M160106</guid>
      <dc:creator>markvt</dc:creator>
      <dc:date>2015-11-04T09:41:16Z</dc:date>
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