The Post-RTC and Thread pool overloaded errors cause the engine to hang and not process the incoming requests.
Here is the sample error for reference:
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2023 May 11 12:21:49:755 GMT -04 CVMLNX1144_2-core ERROR [WorkPool.Thread.2] - [runtime.service] Retrying Action: com.tibco.be.functions.channel.http.HTTPServletResponseFunctions$SendResponseAction@10ca62af
2023 May 11 12:21:49:984 GMT -04 CVMLNX1144_2-core WARN [HTTP-NIO-Worker-1-8] - [runtime.util] [core-class] Thread pool [WorkPool] is overloaded and the job submissions are facing repeated failures. Job [com.tibco.cep.runtime.service.cluster.txn.RtcTransactionManager$TxnTask_Actions@360eb96f] has already been submitted [75] times and is still being rejected.
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This article provides inputs to resolve the Post-RTC/Thread pool overloaded errors reported by the APIX engine.

All Supported Platforms

Please add the below properties in asg_core.cdd file at cluster level:
<property name="be.engine.txn.action.sleeptime" value="20"/>
<property name="be.engine.txn.action.retrycount" value="3"/>
<property name="Agent.core-class.enableParallelOps" value="false"/>

1.)
be.engine.txn.action.sleeptime=20
be.engine.txn.action.retrycount=3

When Post-RTC actions fail, such as acknowledging or sending a message, action handlers try by default 10 times with 500 milliseconds sleep.
These properties reduces the sleeptime and retry counts that helps to reduce the impact of a failed PostRTC operation.

2.)
Agent.core-class.enableParallelOps=false

This property disables the parallelOps, so that PostRTC operations processed by the worker thread itself and not by one of the two pool servers.

Attached is the sample asg_core.cdd file for the reference.