[
https://issues.apache.org/jira/browse/OPENJPA-2610?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Seb Mo updated OPENJPA-2610:
----------------------------
Description:
We get this exception from time to time (at the beginning of running a new
flow).
We get it about once at 10 runs. I've seen this error mentioned in openjpa dev
forum as well:
http://openjpa.208410.n2.nabble.com/Supposed-concurrent-access-issue-to-PCPath-instance-td7585102.html
(just added this reply there as well)
Here is the stack trace (I've obfuscated the query and removed most of our
internal calls due to our comp policy):
<openjpa-0.0.0-rnull nonfatal user error>
org.apache.openjpa.persistence.ArgumentException: Failed to execute query
"SELECT DISTINCT e0 FROM a.b.c.d.OurClass e0 WHERE :p0 MEMBER OF
e0.ourClassSet". Check the query syntax for correctness. See nested exception
for details.
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:872)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:794)
at
org.apache.openjpa.kernel.DelegatingQuery.execute(DelegatingQuery.java:542)
at org.apache.openjpa.persistence.QueryImpl.execute(QueryImpl.java:315)
at
org.apache.openjpa.persistence.QueryImpl.getResultList(QueryImpl.java:331)
.... (internal app code)
Caused by: java.util.ConcurrentModificationException
at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
at java.util.LinkedList$ListItr.next(LinkedList.java:888)
at
org.apache.openjpa.jdbc.kernel.exps.PCPath.getPCPathString(PCPath.java:260)
at
org.apache.openjpa.jdbc.kernel.exps.ContainsExpression.initialize(ContainsExpression.java:44)
at
org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.initialize(SelectConstructor.java:232)
at
org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.newSelect(SelectConstructor.java:173)
at
org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.evaluate(SelectConstructor.java:87)
at
org.apache.openjpa.jdbc.kernel.JDBCStoreQuery.createWhereSelects(JDBCStoreQuery.java:360)
at
org.apache.openjpa.jdbc.kernel.JDBCStoreQuery.executeQuery(JDBCStoreQuery.java:193)
at
org.apache.openjpa.kernel.ExpressionStoreQuery$DataStoreExecutor.executeQuery(ExpressionStoreQuery.java:782)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:1005)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:863)
... 29 more
We've tracked this down as being a problem with the initialize call in the
ContainsExpression method calling the setContainsId while another thread
executing the same ContainsExpression initialize method, doing a
getPCPathString on the same PCPath object.
So while a thread adds elements to the _actions list, another is iterating
through it, causing CME.
The first call to setContainsId will set the _cid flag to true, so after that
flag is set the _actions linkedlist is not updated anymore. (those we only get
the error at the beginning of running a specific flow)
One quick solution that we're testing right now since this is a critical issue
for us, is to add the code in a single sync method
public synchronized void setContainsId(Map contains)
{
String path = getPCPathString();
// update the count for this path
Integer count = (Integer) contains.get(path);
if (count == null)
count = 0;
else
count = count.intValue() + 1;
contains.put(path, count);
setContainsId(count.toString());
}
into the PCPath class and call that from the
ContainsExpression#initialize.
This way the getPCPathString will not get called at the same time with
calling setContainsId.
Now this seems to work for now in our tests, but i'm not that familiar
with openjpa code, so maybe a more elegant solution can be added? Or I'm fine
with moving with this solution unless you see any possible issues with it.
This does not seem to be caused by using the same EM in multiple threads, seems
to be a race condition in using the contains (MEMBER OF) in our queries.
Our query is not a NamedQuery, we build the filters dynamically. Please let me
know if you need more details.
We currently use openjpa 2.1.1 with the plan to migrate, but I've seen the same
code in your latest version, so the problem could be present there as well.
was:
We get this exception from time to time (at the beginning of running a new
flow).
We get it about once at 10 runs. I've seen this error mentioned in openjpa dev
forum as well:
http://openjpa.208410.n2.nabble.com/Supposed-concurrent-access-issue-to-PCPath-instance-td7585102.html
(just added this reply there as well)
Here is the stack trace (I've obfuscated the query and removed most of our
internal calls due to our comp policy):
<openjpa-0.0.0-rnull nonfatal user error>
org.apache.openjpa.persistence.ArgumentException: Failed to execute query
"SELECT DISTINCT e0 FROM a.b.c.d.OurClass e0 WHERE :p0 MEMBER OF
e0.ourClassSet". Check the query syntax for correctness. See nested exception
for details.
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:872)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:794)
at
org.apache.openjpa.kernel.DelegatingQuery.execute(DelegatingQuery.java:542)
at org.apache.openjpa.persistence.QueryImpl.execute(QueryImpl.java:315)
at
org.apache.openjpa.persistence.QueryImpl.getResultList(QueryImpl.java:331)
at
com.cyclonecommerce.persistence.providers.jpa.JpaQuery.execute(JpaQuery.java:228)
at
com.cyclonecommerce.persistence.providers.jpa.JpaQuery.execute(JpaQuery.java:206)
.... (internal app code)
Caused by: java.util.ConcurrentModificationException
at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
at java.util.LinkedList$ListItr.next(LinkedList.java:888)
at
org.apache.openjpa.jdbc.kernel.exps.PCPath.getPCPathString(PCPath.java:260)
at
org.apache.openjpa.jdbc.kernel.exps.ContainsExpression.initialize(ContainsExpression.java:44)
at
org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.initialize(SelectConstructor.java:232)
at
org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.newSelect(SelectConstructor.java:173)
at
org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.evaluate(SelectConstructor.java:87)
at
org.apache.openjpa.jdbc.kernel.JDBCStoreQuery.createWhereSelects(JDBCStoreQuery.java:360)
at
org.apache.openjpa.jdbc.kernel.JDBCStoreQuery.executeQuery(JDBCStoreQuery.java:193)
at
org.apache.openjpa.kernel.ExpressionStoreQuery$DataStoreExecutor.executeQuery(ExpressionStoreQuery.java:782)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:1005)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:863)
... 29 more
We've tracked this down as being a problem with the initialize call in the
ContainsExpression method calling the setContainsId while another thread
executing the same ContainsExpression initialize method, doing a
getPCPathString on the same PCPath object.
So while a thread adds elements to the _actions list, another is iterating
through it, causing CME.
The first call to setContainsId will set the _cid flag to true, so after that
flag is set the _actions linkedlist is not updated anymore. (those we only get
the error at the beginning of running a specific flow)
One quick solution that we're testing right now since this is a critical issue
for us, is to add the code in a single sync method
public synchronized void setContainsId(Map contains)
{
String path = getPCPathString();
// update the count for this path
Integer count = (Integer) contains.get(path);
if (count == null)
count = 0;
else
count = count.intValue() + 1;
contains.put(path, count);
setContainsId(count.toString());
}
into the PCPath class and call that from the
ContainsExpression#initialize.
This way the getPCPathString will not get called at the same time with
calling setContainsId.
Now this seems to work for now in our tests, but i'm not that familiar
with openjpa code, so maybe a more elegant solution can be added? Or I'm fine
with moving with this solution unless you see any possible issues with it.
This does not seem to be caused by using the same EM in multiple threads, seems
to be a race condition in using the contains (MEMBER OF) in our queries.
Our query is not a NamedQuery, we build the filters dynamically. Please let me
know if you need more details.
We currently use openjpa 2.1.1 with the plan to migrate, but I've seen the same
code in your latest version, so the problem could be present there as well.
> Race condition in ContainsExpression class causing
> ConcurrentModificationException on the PCPath _actions linked list
> ---------------------------------------------------------------------------------------------------------------------
>
> Key: OPENJPA-2610
> URL: https://issues.apache.org/jira/browse/OPENJPA-2610
> Project: OpenJPA
> Issue Type: Bug
> Affects Versions: 2.1.1
> Reporter: Seb Mo
>
> We get this exception from time to time (at the beginning of running a new
> flow).
> We get it about once at 10 runs. I've seen this error mentioned in openjpa
> dev forum as well:
> http://openjpa.208410.n2.nabble.com/Supposed-concurrent-access-issue-to-PCPath-instance-td7585102.html
> (just added this reply there as well)
> Here is the stack trace (I've obfuscated the query and removed most of our
> internal calls due to our comp policy):
> <openjpa-0.0.0-rnull nonfatal user error>
> org.apache.openjpa.persistence.ArgumentException: Failed to execute query
> "SELECT DISTINCT e0 FROM a.b.c.d.OurClass e0 WHERE :p0 MEMBER OF
> e0.ourClassSet". Check the query syntax for correctness. See nested exception
> for details.
> at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:872)
> at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:794)
> at
> org.apache.openjpa.kernel.DelegatingQuery.execute(DelegatingQuery.java:542)
> at org.apache.openjpa.persistence.QueryImpl.execute(QueryImpl.java:315)
> at
> org.apache.openjpa.persistence.QueryImpl.getResultList(QueryImpl.java:331)
> .... (internal app code)
> Caused by: java.util.ConcurrentModificationException
> at
> java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
> at java.util.LinkedList$ListItr.next(LinkedList.java:888)
> at
> org.apache.openjpa.jdbc.kernel.exps.PCPath.getPCPathString(PCPath.java:260)
> at
> org.apache.openjpa.jdbc.kernel.exps.ContainsExpression.initialize(ContainsExpression.java:44)
>
> at
> org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.initialize(SelectConstructor.java:232)
>
> at
> org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.newSelect(SelectConstructor.java:173)
>
> at
> org.apache.openjpa.jdbc.kernel.exps.SelectConstructor.evaluate(SelectConstructor.java:87)
>
> at
> org.apache.openjpa.jdbc.kernel.JDBCStoreQuery.createWhereSelects(JDBCStoreQuery.java:360)
>
> at
> org.apache.openjpa.jdbc.kernel.JDBCStoreQuery.executeQuery(JDBCStoreQuery.java:193)
>
> at
> org.apache.openjpa.kernel.ExpressionStoreQuery$DataStoreExecutor.executeQuery(ExpressionStoreQuery.java:782)
>
> at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:1005)
> at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:863)
> ... 29 more
>
> We've tracked this down as being a problem with the initialize call in the
> ContainsExpression method calling the setContainsId while another thread
> executing the same ContainsExpression initialize method, doing a
> getPCPathString on the same PCPath object.
> So while a thread adds elements to the _actions list, another is iterating
> through it, causing CME.
> The first call to setContainsId will set the _cid flag to true, so after that
> flag is set the _actions linkedlist is not updated anymore. (those we only
> get the error at the beginning of running a specific flow)
> One quick solution that we're testing right now since this is a critical
> issue for us, is to add the code in a single sync method
> public synchronized void setContainsId(Map contains)
> {
> String path = getPCPathString();
> // update the count for this path
> Integer count = (Integer) contains.get(path);
> if (count == null)
> count = 0;
> else
> count = count.intValue() + 1;
> contains.put(path, count);
> setContainsId(count.toString());
> }
>
> into the PCPath class and call that from the
> ContainsExpression#initialize.
>
> This way the getPCPathString will not get called at the same time
> with calling setContainsId.
>
> Now this seems to work for now in our tests, but i'm not that
> familiar with openjpa code, so maybe a more elegant solution can be added? Or
> I'm fine with moving with this solution unless you see any possible issues
> with it.
>
> This does not seem to be caused by using the same EM in multiple threads,
> seems to be a race condition in using the contains (MEMBER OF) in our
> queries.
> Our query is not a NamedQuery, we build the filters dynamically. Please let
> me know if you need more details.
> We currently use openjpa 2.1.1 with the plan to migrate, but I've seen the
> same code in your latest version, so the problem could be present there as
> well.
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