@nifier
I would not expect much difference between making the stop request via the NiFi UI or via a rest-api call. Even when you make a request to stop components via the NiFi UI, the UI may quickly show the "stopped" icon on the component, but any active threads are not killed in that process. In fact the processor is considered "stopping" until all its active threads complete however long that takes. While still in the state of stopping, you can not modify those components. A component is considered stopping if its "activeThreadCount" is not 0.
when you are executing your rest-api script without the delay, what exception are you encountering?
This one?
unable to fulfill this request due to: Cannot start component with <component id> because it is currently stopping
Above means you have active threads.
Perhaps you can build a wait loop around above response until the active threads complete. Or you can capture that component id and execute a terminate threads command on it.
../nifi-api/processors/<component id>/threads -X DELETE
Terminating threads will not cause data loss. NiFi is not killing any threads in this process, only way to kill threads is via a NiFi restart. Terminating threads on component just shifts the thread to dev null and unhooks it from the FlowFile(s) it is associated with in the inbound connection. When the processor is restarted, the FlowFile(s) will be reprocessed by the component. Should the "terminated" thread complete execution its logging and output just goes to dev null and results are not written back to a FlowFile, but depending on processor it could end up in duplicate data on a destination system if the tread is sending data out of NiFi since NiFi will reprocess the FlowFile originally associated with that terminated thread next time processor is started.
The other option is to get the status of components for the process group you stopped and parse the json for any "activeThreadCount" were count is not 0 and wait 1 sec and make request again and then repeat this loop until all are 0 before making your next rest-api call.
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Thank you,
Matt
