TestFailoverProxy fails intermittently on trunk
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Key: HADOOP-7888
URL: https://issues.apache.org/jira/browse/HADOOP-7888
Project: Hadoop Common
Issue Type: Bug
Components: test
Affects Versions: 0.24.0
Reporter: Jason Lowe
TestFailoverProxy can fail intermittently with the failures occurring in
testConcurrentMethodFailures(). The test has a race condition where the two
threads may be sequentially invoking the unreliable interface rather than
concurrently. Currently the proxy provider's getProxy() method contains the
thread synchronization to enforce a concurrent invocation, but examining the
source to RetryInvocationHandler.invoke() shows that the call to getProxy()
during failover is too late to enforce a truly concurrent invocation.
For this particular test, one thread could race ahead and block on the
CountDownLatch in getProxy() before the other thread even enters
RetryInvocationHandler.invoke(). If that happens the second thread will cache
the newly updated value for proxyProviderFailoverCount, since the failover has
mostly been processed by the original thread. Therefore the second thread ends
up assuming no other thread is present, performs a failover, and the test fails
because two failovers occurred instead of one.
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