Handle or document ReflectionToStringBuilder and ToStringBuilder for
collections that are not thread safe
---------------------------------------------------------------------------------------------------------
Key: LANG-762
URL: https://issues.apache.org/jira/browse/LANG-762
Project: Commons Lang
Issue Type: Bug
Components: lang.builder.*
Environment: Apache Maven 3.0.3 (r1075438; 2011-02-28 12:31:09-0500)
Maven home: C:\Java\apache-maven-3.0.3\bin\..
Java version: 1.6.0_24, vendor: Sun Microsystems Inc.
Java home: C:\Program Files\Java\jdk1.6.0_24\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 7", version: "6.1", arch: "amd64", family: "windows"
Reporter: Gary D. Gregory
Moving discussion here from https://issues.apache.org/jira/browse/POOL-191
ConcurrentModificationException in GenericObjectPool LinkedList.
It is possible to get a {{ConcurrentModificationException}} in a {{LinkedList}}
from a Commons Pool {{GenericObjectPool}}.
This happens when I call {{ReflectionToStringBuilder.toString(this)}} from a
subclass of {{GenericObjectPool}}. My guess is that it would happen with just
{{ReflectionToStringBuilder.toString(gop)}}. IOW, subclassing does not have
anything to do with it I would venture.
For example, in this stack trace {{JmsSessionPool}} is a subclass of
{{GenericObjectPool}}.
{noformat}
java.util.ConcurrentModificationException
at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:761)
at java.util.LinkedList$ListItr.next(LinkedList.java:696)
at java.util.AbstractCollection.toString(AbstractCollection.java:421)
at java.lang.String.valueOf(String.java:2826)
at java.lang.StringBuffer.append(StringBuffer.java:219)
at
org.apache.commons.lang3.builder.ToStringStyle.appendDetail(ToStringStyle.java:598)
at
org.apache.commons.lang3.builder.ToStringStyle.appendInternal(ToStringStyle.java:473)
at org.apache.commons.lang3.builder.ToStringStyle.append(ToStringStyle.java:436)
at
org.apache.commons.lang3.builder.ToStringBuilder.append(ToStringBuilder.java:848)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.appendFieldsIn(ReflectionToStringBuilder.java:528)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.toString(ReflectionToStringBuilder.java:692)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.toString(ReflectionToStringBuilder.java:288)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.toString(ReflectionToStringBuilder.java:119)
at
com.seagullsw.appinterface.comm.jms.JmsSessionPool.toString(JmsSessionPool.java:120)
at java.lang.String.valueOf(String.java:2826)
at java.lang.StringBuffer.append(StringBuffer.java:219)
at
org.apache.commons.lang3.builder.ToStringStyle.appendDetail(ToStringStyle.java:586)
at
org.apache.commons.lang3.builder.ToStringStyle.appendInternal(ToStringStyle.java:550)
at org.apache.commons.lang3.builder.ToStringStyle.append(ToStringStyle.java:436)
at
org.apache.commons.lang3.builder.ToStringBuilder.append(ToStringBuilder.java:848)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.appendFieldsIn(ReflectionToStringBuilder.java:528)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.toString(ReflectionToStringBuilder.java:689)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.toString(ReflectionToStringBuilder.java:288)
at
org.apache.commons.lang3.builder.ReflectionToStringBuilder.toString(ReflectionToStringBuilder.java:119)
at
com.seagullsw.appinterface.server.comm.BasicCommunicationManager.toString(BasicCommunicationManager.java:828)
at
com.seagullsw.appinterface.server.comm.BasicCommunicationManager.toString(BasicCommunicationManager.java:817)
at java.lang.String.valueOf(String.java:2826)
at java.lang.StringBuilder.append(StringBuilder.java:115)
at
com.seagullsw.appinterface.server.AisHelper.waitForCommuncationManagers(AisHelper.java:217)
at com.seagullsw.appinterface.server.AisHelper.start(AisHelper.java:136)
at
com.seagullsw.appinterface.server.AisHelper.startFromResource(AisHelper.java:161)
at
com.seagullsw.appinterface.server.AbstractServerJunit4.startServer(AbstractServerJunit4.java:179)
at
com.seagullsw.appinterface.server.comm.jms.AbstractJmsRoundtripMaxConcurrencyTestCase.setUpOnce(AbstractJmsRoundtripMaxConcurrencyTestCase.java:141)
at
com.seagullsw.appinterface.server.comm.jms.ibmmq.JmsRoundtripMaxConcurrency032TestCase.setUpOnce(JmsRoundtripMaxConcurrency032TestCase.java:40)
{noformat}
We should either:
- Document ReflectionToStringBuilder and ToStringBuilder such that call sites
use synchronized if the object passed in contains collections that are not
thread-safe. F
or example:
{code:java}
@Override
public synchronized String toString() {
return ReflectionToStringBuilder.toString(this);
}
{code}
- Or have our code in ReflectionToStringBuilder and ToStringBuilder lock
collections while they are being toString'd.
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