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From Jeremy Farbota <>
Subject NiFi cluster sluggish...fine after VMs rebooted
Date Tue, 12 Sep 2017 17:38:23 GMT

We're having an issue recently where flow files get queued up and sit in
the flows (seems like the whole system has back-pressure) seemingly at
random times. A few weeks back, we had a problem where the provenance repo
was not keeping up with the creation of flow files. We switched to a
VolatileProvenanceRepo and that issue was resolved.[1]

Since then, we'll occasionally have the system slow down without any errors
or warnings. It seems that NiFi is unable to move flow files through the
system after they are created. I know it is happening when I see the total
number of flow files spike and a few things queued at weird places (e.g.
replace text, update attribute, etc. where you usually never see anything
queued). Eventually I end up with a huge queue on the last step which
usually involves a controller (PutSql or PutHDFS).

We've found that this issues is resolved by rebooting all of the machines.
Is it possible that the volatile provenance is somehow still getting behind
and when we reboot that is flushed thus removing back-pressure? We're
trying to figure out why the reboot helps. We're also trying to understand
more about different situations where NiFi internally slows down the flows.

We see some normal errors in the logs (e.g. security expired, minor errors
due to a test flow that has issues). No errors that suggest the system is
applying back pressure.

At this point, I'm going to create a reporting process to alert dev ops
when there are files heavily queued so we can get alerted when it's

Thanks in advance.


[image: Payoff, Inc.]
*Jeremy Farbota*
Software Engineer, Data
Payoff, Inc.

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