Gemfire client server topology throws NoAvailableL

I have gemfire client server configured via gfe based xml. The locator, cache server and client cache start through these xml configurations. I populate my Region by getting data from database. The client uses data from this Region. It works very well for about 2 hours but after that the client starts throwing following exception and trace.

I don't do any changes to running application. That means the locator and cache server should be running at all times. Any help would be great. Thanks.

com.gemstone.gemfire.cache.client.NoAvailableLocatorsException: Unable to connect to any locators in the list [/locator-host:locator-port] at com.gemstone.gemfire.cache.client.internal.AutoConnectionSourceImpl.findServer(AutoConnectionSourceImpl.java:132) at com.gemstone.gemfire.cache.client.internal.ConnectionFactoryImpl.createClientToServerConnection(ConnectionFactoryImpl.java:205) at com.gemstone.gemfire.cache.client.internal.pooling.ConnectionManagerImpl.exchangeConnection(ConnectionManagerImpl.java:418) at com.gemstone.gemfire.cache.client.internal.OpExecutorImpl.execute(OpExecutorImpl.java:173) at com.gemstone.gemfire.cache.client.internal.OpExecutorImpl.execute(OpExecutorImpl.java:114) at com.gemstone.gemfire.cache.client.internal.PoolImpl.execute(PoolImpl.java:638) at com.gemstone.gemfire.cache.client.internal.GetOp.execute(GetOp.java:89) at com.gemstone.gemfire.cache.client.internal.ServerRegionProxy.get(ServerRegionProxy.java:126) at com.gemstone.gemfire.internal.cache.LocalRegion.findObjectInSystem(LocalRegion.java:2767) at com.gemstone.gemfire.internal.cache.LocalRegion.nonTxnFindObject(LocalRegion.java:1605) at com.gemstone.gemfire.internal.cache.LocalRegionDataView.findObject(LocalRegionDataView.java:133) at com.gemstone.gemfire.internal.cache.LocalRegion.get(LocalRegion.java:1489) at com.gemstone.gemfire.internal.cache.LocalRegion.get(LocalRegion.java:1451) at com.gemstone.gemfire.internal.cache.AbstractRegion.get(AbstractRegion.java:278)

Do you have anything in your locator or server logs? That exception indicates the client is trying to create a new connection and can't connect to a locator.

If your locator goes down, the client might still be able to work for a while using it's existing connections because it doesn't need to go back to the locator until it needs a new connection.