@Jisson  I don't see ExecuteStream in the thread dump provided.   Let's clarify first what you mean by "stuck"... When the processor is in this "stuck" state, does the processor indicate that it has an active thread?  A NiFi processor will show a small number in its upper right corner when it has an active thread(s).  Below example shows an ExecuteStreamCommand processor with "1" active thread: If your processor has no active threads, it is not stuck/hung.  It is simply does not have a thread to execute the command.  This could happen if all thread from the max timer driven thread pool in NiFi are already being used by other components.  We would call this a thread starved processor.  If your CPU load average is good, you could increase the size of the thread pool to see if that helps.  NiFi out-of-the-box sets the "Maximum Timer Driven Thread Count" Pool to 10.  You can change this from the NiFi Ui --> global menu (upper right corner) --> Controller Settings --> General tab. If your processor does show an active threads, i'd expect to see that thread in the thread dump.  Also keep in mind that a single thread dump is not very useful.  A thread may not be HUNG, but rather long running for example.  So getting a series of thread dumps spread out to compare would allow you to see if the thread stack is changing over time indicating not hung but slow.  In the case of your ExecuteStreamCommand processor, it is calling a custom python script and the waits for the return from that script.  Then comes the challenge is the thread dump indicates it is waiting on your python script return to figure out why your python scripts is hanging or taking a very long time all of a sudden. Not something that can be troubleshot through NiFi. Hope this helps you in your troubleshooting journey. If you found any of the suggestions/solutions provided helped you with your issue, please take a moment to login and click "Accept as Solution" on one or more of them that helped. Thank you, Matt ... View more