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Unable to accept requests from event receivers (WSO2 event publisher)

Sample Error log

Code Block

org.wso2.carbon.databridge.agent.exception.EventQueueFullException: Cannot send events because the event queue is full
at org.wso2.carbon.databridge.agent.endpoint.DataEndpointGroup$EventQueue.tryPut(DataEndpointGroup.java:124)
at org.wso2.carbon.databridge.agent.endpoint.DataEndpointGroup$EventQueue.access$100(DataEndpointGroup.java:104)
at org.wso2.carbon.databridge.agent.endpoint.DataEndpointGroup.tryResendEvents(DataEndpointGroup.java:295)
at org.wso2.carbon.databridge.agent.endpoint.DataEndpoint$EventPublisher.handleFailedEvents(DataEndpoint.java:271)
at org.wso2.carbon.databridge.agent.endpoint.DataEndpoint$EventPublisher.run(DataEndpoint.java:245)
at java.lang.Thread.run(Thread.java:745)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
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)
Caused by: com.lmax.disruptor.InsufficientCapacityException

Occurrence

This occurs when events published by WSO2 DAS via a publisher of the wso2event type do not reach the endpoint.

Possible reasons

A failure in the network connection.
Unavailability of the receiver node to which the events are published (e.g., if it is unreachable, shut down etc.)
The receiver not being responsive (e.g., due to an error is the connection, due to the receiver queue being full etc.)
The internal queue of the

recover

receiver node to which the events are published being full.

Recommended action

Increase the event queue size at databridge level. This is done by editing the QueueSize parameter in the <DAS_HOME>/repository/conf/data-bridge/data-agent-config.xml file. The result of doing this also depends on the other parameters configured in the data-agent-config.xml file. Therefore, for more details, see Performance Tuning - Publishing Events.
Check the connectivity health of the connection with the receiver endpoint.
Check the status of the receiver, and ensure that it is able to accept messages.
Use a blocking publisher of the wso2event type instead of a non-blocking

WSO2 event publisher. For more information on how to configure a non-bloking data publisher, see Publishing Data Using Java Client Through Thrift or Binary - Data Publisher Sample .

publisher. If the disruptor queue is full at a given time, a blocking publisher waits until there is space in the queue to insert the event instead of returning the method call to publish the event and throwing the EventQueueFull exception. The following diagrams illustrate the difference between blocking and non-blocking publishers in their approach to handle events to be published when the disruptor queue is full.
Info
This can cause back pressure on the publisher. As a result, the publisher itself can be blocked from publishing events.

Blocking Publisher
Image Added Non-blocking publisher
Image Added

Versions Compared

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Key

Unable to accept requests from event receivers (WSO2 event publisher)