What's the meaning of the number label on NiFi processor

[#1]

Hi,

Maybe this is a newbie question, but what's the meaning for the number that appears on the upper-right corner of the processor in this creenshoot ?

Thanks

[#2 · Accepted solution]

That is the number of threads currently running in the processor. You sometimes see this if you have threads running for a while (e.g. long running processes like TailFile, or Listening processes). If you increase the number of concurrent tasks, you will also see this go up.

[#3]

Most threads are very short running (miliseconds) and since the NiFi refresh rate defaults are every 30 seconds. The number in the upper right corner may not represent a still running thread. In your screenshot above, the TailFile processor shows as having recorded the completion of 473,336 Tasks (Each task using a thread to complete) and a total cumulative thread time of only 2 min, 52 seconds and 334 milliseconds over the past 5 minutes.

Long running threads will show much different stats in the Tasks/Time field.

[#4]

What is a task in this context ? reading a line ?