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From Panos Geo <panospanos1...@outlook.com>
Subject Re: NiFi stops processing further flowfiles
Date Mon, 27 Nov 2017 06:31:25 GMT
Hello Juan,


Thanks for your reply. I'll keep an eye out on the upper left corner of the UI indeed 😉


Cheers,

Panos


________________________________
From: Juan Sequeiros <hellojuan@gmail.com>
Sent: Friday, November 24, 2017 6:59 PM
To: users@nifi.apache.org
Subject: Re: NiFi stops processing further flowfiles

Hi Panos,

The scheduling strategy defaults to timer driven on processors and I've always avoided using
event driven so if you are not purposely using it I would just leave that setting alone. It
even warns you that it is experimental.

Your thread count is shown on the UI or can be called through RestApi /nifi-api/flow/status

Thanks,

Juan

On Fri, Nov 24, 2017 at 1:24 PM Panos Geo <panospanos1983@outlook.com<mailto:panospanos1983@outlook.com>>
wrote:

Thanks for your reply Juan.


I have been using NiFi for almost 2 years now and didn't know about this setting. I 'll try
to increase it and see what happens 😊


Does it also make sense to increase the "Maximum Event Driven Thread Count"?


Finally, is there a way to monitor thread usage within NiFi?


Many thanks,

Panos


________________________________
From: Juan Sequeiros <hellojuan@gmail.com<mailto:hellojuan@gmail.com>>
Sent: Friday, November 24, 2017 4:50 PM
To: users@nifi.apache.org<mailto:users@nifi.apache.org>
Subject: Re: NiFi stops processing further flowfiles

Good afternoon,

My quick guess is you are running out of threads.
If your system can handle it increase the default "max thread" count found:

Left side controller settings > Maximum timer driven thread count

On Fri, Nov 24, 2017 at 10:47 AM Panos Geo <panospanos1983@outlook.com<mailto:panospanos1983@outlook.com>>
wrote:

Hello all,

We are running NiFi in a docker container that has roughly 500 processors running. These include
consuming messages (MQTT), interaction with a database and some data processing with execute
scripts. Our NiFi version is v.1.4.0 and this instance has 18GB of RAM with 12GB allocated
to Java heap.

Quite recently we increased the load of the incoming messages (1000messages/minute) that lead
to more files being queued and some backpressure. We then have experienced what appears to
be some kind of deadlock. NiFi stops processing any flowfiles and the processors running get
stuck (there is a thread running constantly; we see 1 at the top right corner of the processor).
If we try to stop these processors the icon gets changed to stop, but we now have 2 threads
stuck at the top right corner of the processor. We cannot start these processors again and
no other data flow is being processed unless we restart NiFi. We have experienced this multiple
times over the past week.

I am attaching a nifi dump in case it helps. Our nifi.properties is fairly standard (we just
have smaller retention periods for content and provenance).

Any thoughts? What can we do to debug this further?

Many thanks,
Panos
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