Exception when the same document is saved at the same time in 2 different threads

Caused by: org.apache.velocity.exception.MethodInvocationException: Invocation of method 'save' in  class com.xpn.xwiki.api.Document threw exception com.xpn.xwiki.XWikiException: Error number 3201 in 3: Exception while saving document xwiki:IRC.xwikitestArchive20141113 at 2331:unknown namespace[line 61, column 26]
	at org.apache.velocity.runtime.parser.node.ASTMethod.handleInvocationException(ASTMethod.java:243)
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:187)
	at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
	at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:567)
	at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:71)
	at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:142)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
	at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:87)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluateInternal(DefaultVelocityEngine.java:256)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:222)
	... 24 more
Caused by: com.xpn.xwiki.XWikiException: Error number 3201 in 3: Exception while saving document xwiki:IRC.xwikitestArchive20141113
	at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:780)
	at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:178)
	at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:171)
	at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:1296)
	at com.xpn.xwiki.api.Document.saveDocument(Document.java:2332)
	at com.xpn.xwiki.api.Document.save(Document.java:2234)
	at sun.reflect.GeneratedMethodAccessor553.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
	... 33 more
Caused by: org.hibernate.HibernateException: Failed to commit or rollback transaction. Root cause []
	at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:1022)
	at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:770)
	... 44 more
Caused by: org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
	at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96)
	at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
	at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
	at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:268)
	at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:184)
	at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
	at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
	at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1216)
	at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:383)
	at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:133)
	at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:1015)
	... 45 more
Caused by: java.sql.BatchUpdateException: integrity constraint violation: unique constraint or index violation; SYS_PK_10305 table: XWIKIRCS
	at org.hsqldb.jdbc.JDBCPreparedStatement.executeBatch(Unknown Source)
	at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:297)
	at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:297)
	at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
	at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
	... 53 more

      ]
	at org.xwiki.ircbot.internal.wiki.DefaultExecutor.renderContent(DefaultExecutor.java:135) ~[org%252Exwiki%252Eplatform%253Axwiki-platform-ircbot-api-6%252E3.jar:na]
	at org.xwiki.ircbot.internal.wiki.DefaultExecutor.execute(DefaultExecutor.java:104) ~[org%252Exwiki%252Eplatform%253Axwiki-platform-ircbot-api-6%252E3.jar:na]
	at org.xwiki.ircbot.internal.wiki.DefaultWikiIRCModel.executeAsUser(DefaultWikiIRCModel.java:197) ~[org%252Exwiki%252Eplatform%253Axwiki-platform-ircbot-api-6%252E3.jar:na]
	at org.xwiki.ircbot.internal.wiki.WikiIRCBotListener.executeAsUser(WikiIRCBotListener.java:239) ~[org%252Exwiki%252Eplatform%253Axwiki-platform-ircbot-api-6%252E3.jar:na]
	at org.xwiki.ircbot.internal.wiki.WikiIRCBotListener.onEvent(WikiIRCBotListener.java:208) ~[org%252Exwiki%252Eplatform%253Axwiki-platform-ircbot-api-6%252E3.jar:na]
	at org.pircbotx.hooks.managers.ThreadedListenerManager$1.run(ThreadedListenerManager.java:91) [org%252Epircbotx%253Apircbotx-1%252E6.jar:na]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) [na:1.7.0_72]
	at java.util.concurrent.FutureTask.run(FutureTask.java:262) [na:1.7.0_72]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_72]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_72]
	at java.lang.Thread.run(Thread.java:745) [na:1.7.0_72]
	at org.xwiki.ircbot.internal.XWikiContextualizedThreadFactory$XWikiContextualizedThread.run(XWikiContextualizedThreadFactory.java:121) [org%252Exwiki%252Eplatform%253Axwiki-platform-ircbot-api-6%252E3.jar:na]