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Evidence of JVM becomes unresponsive



Evidence of JVM becomes unresponsive particularly in relation to a node hosting a DNode Cassandra process as part of a cluster. The external system invoking Pega's next-best-action service reports no response. Issues occur in the PegaRULES log when the dataflow runs. 'Caused By' stack displays for both the scenarios.

Error Messages


Caused by:com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (no host was tried)
at com.datastax.driver.core.RequestHandler.reportNoMoreHosts( ~[cassandra-driver-core-3.1.2.jar:?]
at com.datastax.driver.core.RequestHandler.access$1000( ~[cassandra-driver-core-3.1.2.jar:?]

Steps to Reproduce



Root Cause

Memory issue related to the Cassandra process and it's database driver. A key element in the issue is the use of IBM JDK.


Perform the following local-change:
Disable the direct memory using the below JVM argument settings:
  • Dio.netty.noPreferDirect=true 
  • Dio.netty.allocator.type=unpooled 
  • Dio.netty.maxDirectMemory=0



Published April 4, 2019 - Updated October 8, 2020

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