using JDBC_PING, create a very simple JChannel, unique constraint violated exception will throw sometimes.

it's a occationally issue. to easy reproduce it, using debug to let threads hold on JDBC_PING.writeToFile(...). line insert(...) (JDBC_PING line 246 in JGroups2.12.1.Final) you can find three threads will be hold on here. then using debug to step over this line, the unique constraint violated exception will throw.

I uploaded a debug diagram in here http://ww2.sinaimg.cn/mw600/649a9869jw1dr8m399uqdj.jpg

following is the exception stack:

SEVERE: Error updating JDBC_PING table
java.sql.SQLException: ORA-00001: unique constraint (HLIUCLUSTER.SYS_C0038277) violated

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:331)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:288)
at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:745)
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:219)
at oracle.jdbc.driver.T4CPreparedStatement.executeForRows(T4CPreparedStatement.java:970)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1190)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3370)
at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:3454)
at org.jgroups.protocols.JDBC_PING.insert(JDBC_PING.java:265)
at org.jgroups.protocols.JDBC_PING.writeToFile(JDBC_PING.java:246)
at org.jgroups.protocols.FILE_PING.sendGetMembersRequest(FILE_PING.java:115)
at org.jgroups.protocols.Discovery$PingSenderTask$1.run(Discovery.java:527)
at org.jgroups.util.TimeScheduler2$RecurringTask.run(TimeScheduler2.java:592)
at org.jgroups.util.TimeScheduler2$MyTask.run(TimeScheduler2.java:524)
at org.jgroups.util.TimeScheduler2$Entry.execute(TimeScheduler2.java:429)
at org.jgroups.util.TimeScheduler2$1.run(TimeScheduler2.java:295)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)