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Locator mismatch and exception thrown for backwards compatibility in Pivotal GemFire

Environment

Product Version
Pivotal GemFire 7.0.1.x

Symptom

When a locator attempts to communicate with an older version locator on a different WAN cluster, the following exception will be seen in the older locator's system log:

[severe 2016/07/27 11:25:59.556 IST locator1 <locator request thread[1]> tid=0x25] Exception in processing request from 10.112.204.114
java.lang.ClassNotFoundException: com.gemstone.org.jgroups.stack.tcpserver.VersionRequest
at com.gemstone.gemfire.internal.ClassPathLoader.forName(ClassPathLoader.java:342) at com.gemstone.gemfire.internal.InternalDataSerializer.getCachedClass(InternalDataSerializer.java:3788) at com.gemstone.gemfire.DataSerializer.readClass(DataSerializer.java:280) at com.gemstone.gemfire.internal.InternalDataSerializer.readDataSerializable(InternalDataSerializer.java:2391) at com.gemstone.gemfire.internal.InternalDataSerializer.basicReadObject(InternalDataSerializer.java:2747) at com.gemstone.gemfire.DataSerializer.readObject(DataSerializer.java:3212) at com.gemstone.org.jgroups.stack.tcpserver.TcpServer$3.run(TcpServer.java:283) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745)

Cause

These exceptions are a consequence of the "rolling-upgrade" changes made in GemFire 7.1. Beginning with that version, processes communicating with the locator send it a VersionRequest to determine the GemFire version it is running to understand how to communicate with it. GemFire 7.0.1 does not know how to handle VersionRequest messages. This situation will not cause the locator to malfunction, nor the processes communicating with it, as they will assume it is running a pre-7.1 version of GemFire and choose the appropriate on-wire communication protocol when interacting with it.

Resolution

These exceptions can safely be ignored.

 

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