Anyone who knows how to clear the the messages stuck in IS trigger queue without restarting the IS.
I went to Integration Server UI > Settings > Messaging > Broker Configuration > Broker/Local Trigger Management.
I can only suspend and resume Document retrieval and Document processing and change the number of threads in each, but there is no tool to delete or clear the messages from here. I have messages in these queues which are stuck and no longer processing.
I could not just restart the server everytime there is something stuck.