We have recently observed a strange occurrence when sending and receiving queue messages on the SwiftMQ HA 9.4.2.
Application A has several threads that always post a read on Queue A.
Application B has several threads that always post a read on Queue B.
Application A sends a message to Queue B.
Application B receives the message from Queue B about 5 seconds late.
After Application B processes the message, it sends a reply message to Queue A.
Application A receives the reply message from Queue A about 30 seconds late.
System time of the servers on which Application A and Application B run are in sync.
Load going through Application A and Application B at the time was about 10 transactions per second, all of which go through SwiftMQ as well.
Any clue on this occurrence? Is there any means for us to troubleshoot the issue?
Any server logs or client logs we can enable to help with the troubleshooting?
That might be flow control. Do you see a fc delay on these queues with SwiftMQ Explorer? If yes, you need to adjust attribute "flowcontrol-start-queuesize" for these queues to allow larger backlogs before flow control is activated. Look here.