Raising this thread from the dead...
Having issues with IO to the flowfile repository. NiFi will show 500k
flow files and a size of ~1.7G - but the size on disk on each of the 4
nodes is massive - over 100G, and disk IO to the flowfile spindle is
just pegged doing writes.
I do have ExtractText processors that take the flowfile content (.*) and
put it into an attribute, but the sizes of these is maybe in the 10k at
most size. How can I find out what module (there are some 2200) is
causing the issue? I think I'm doing something fundamentally wrong with
NiFi. :)
Perhaps I should change the size of all the queues to something less
than 10k/1G?
Under cluster/FLOWFILE STORAGE, one of the nodes shows 3.74TBytes of
usage, but it's actually ~150G on disk. The other nodes are correct.
Ideas on what to debug?
Thank you!
-Joe (NiFi 1.18)
On 3/22/2023 12:49 PM, Mark Payne wrote:
OK. So changing the checkpoint internal to 300 seconds might help
reduce IO a bit. But it will cause the repo to become much larger, and
it will take much longer to startup whenever you restart NiFi.
The variance in size between nodes is likely due to how recently it’s
checkpointed. If it stays large like 31 GB while the other stay small,
that would be interesting to know.
Thanks
-Mark
On Mar 22, 2023, at 12:45 PM, Joe Obernberger
<[email protected]> wrote:
Thanks for this Mark. I'm not seeing any large attributes at the
moment but will go through this and verify - but I did have one queue
that was set to 100k instead of 10k.
I set the nifi.cluster.node.connection.timeout to 30 seconds (up from
5) and the nifi.flowfile.repository.checkpoint.interval to 300
seconds (up from 20).
While it's running the size of the flowfile repo varies (wildly?) on
each of the nodes from 1.5G to over 30G. Disk IO is still very high,
but it's running now and I can use the UI. Interestingly at this
point the UI shows 677k files and 1.5G of flow. But disk usage on the
flowfile repo is 31G, 3.7G, and 2.6G on the 3 nodes. I'd love to
throw some SSDs at this problem. I can add more nifi nodes.
-Joe
On 3/22/2023 11:08 AM, Mark Payne wrote:
Joe,
The errors noted are indicating that NiFi cannot communicate with
registry. Either the registry is offline, NiFi’s Registry Client is
not configured properly, there’s a firewall in the way, etc.
A FlowFile repo of 35 GB is rather huge. This would imply one of 3
things:
- You have a huge number of FlowFiles (doesn’t seem to be the case)
- FlowFiles have a huge number of attributes
or
- FlowFiles have 1 or more huge attribute values.
Typically, FlowFile attribute should be kept minimal and should
never contain chunks of contents from the FlowFile content. Often
when we see this type of behavior it’s due to using something like
ExtractText or EvaluateJsonPath to put large blocks of content into
attributes.
And in this case, setting Backpressure Threshold above 10,000 is
even more concerning, as it means even greater disk I/O.
Thanks
-Mark
On Mar 22, 2023, at 11:01 AM, Joe Obernberger
<[email protected]> wrote:
Thank you Mark. These are SATA drives - but there's no way for the
flowfile repo to be on multiple spindles. It's not huge - maybe
35G per node.
I do see a lot of messages like this in the log:
2023-03-22 10:52:13,960 ERROR [Timer-Driven Process Thread-62]
o.a.nifi.groups.StandardProcessGroup Failed to synchronize
StandardProcessGroup[identifier=861d3b27-aace-186d-bbb7-870c6fa65243,name=TIKA
Handle Extract Metadata] with Flow Registry because could not
retrieve version 1 of flow with identifier
d64e72b5-16ea-4a87-af09-72c5bbcd82bf in bucket
736a8f4b-19be-4c01-b2c3-901d9538c5ef due to: Connection refused
(Connection refused)
2023-03-22 10:52:13,960 ERROR [Timer-Driven Process Thread-62]
o.a.nifi.groups.StandardProcessGroup Failed to synchronize
StandardProcessGroup[identifier=bcc23c03-49ef-1e41-83cb-83f22630466d,name=WriteDB]
with Flow Registry because could not retrieve version 2 of flow
with identifier ff197063-af31-45df-9401-e9f8ba2e4b2b in bucket
736a8f4b-19be-4c01-b2c3-901d9538c5ef due to: Connection refused
(Connection refused)
2023-03-22 10:52:13,960 ERROR [Timer-Driven Process Thread-62]
o.a.nifi.groups.StandardProcessGroup Failed to synchronize
StandardProcessGroup[identifier=bc913ff1-06b1-1b76-a548-7525a836560a,name=TIKA
Handle Extract Metadata] with Flow Registry because could not
retrieve version 1 of flow with identifier
d64e72b5-16ea-4a87-af09-72c5bbcd82bf in bucket
736a8f4b-19be-4c01-b2c3-901d9538c5ef due to: Connection refused
(Connection refused)
2023-03-22 10:52:13,960 ERROR [Timer-Driven Process Thread-62]
o.a.nifi.groups.StandardProcessGroup Failed to synchronize
StandardProcessGroup[identifier=920c3600-2954-1c8e-b121-6d7d3d393de6,name=Save
Binary Data] with Flow Registry because could not retrieve version
1 of flow with identifier 7a8c82be-1707-4e7d-a5e7-bb3825e0a38f in
bucket 736a8f4b-19be-4c01-b2c3-901d9538c5ef due to: Connection
refused (Connection refused)
A clue?
-joe
On 3/22/2023 10:49 AM, Mark Payne wrote:
Joe,
1.8 million FlowFiles is not a concern. But when you say “Should I
reduce the queue sizes?” it makes me wonder if they’re all in a
single queue?
Generally, you should leave the backpressure threshold at the
default 10,000 FlowFile max. Increasing this can lead to huge
amounts of swapping, which will drastically reduce performance and
increase disk utilization very significantly.
Also from the diagnostics, it looks like you’ve got a lot of CPU
cores, but you’re not using much. And based on the amount of disk
space available and the fact that you’re seeing 100% utilization,
I’m wondering if you’re using spinning disks, rather than SSDs? I
would highly recommend always running NiFi with ssd/nvme drives.
Absent that, if you have multiple disk drives, you could also
configure the content repository to span multiple disks, in order
to spread that load.
Thanks
-Mark
On Mar 22, 2023, at 10:41 AM, Joe Obernberger
<[email protected]> wrote:
Thank you. Was able to get in.
Currently there are 1.8 million flow files and 3.2G. Is this too
much for a 3 node cluster with mutliple spindles each (SATA drives)?
Should I reduce the queue sizes?
-Joe
On 3/22/2023 10:23 AM, Phillip Lord wrote:
Joe,
If you need the UI to come back up, try setting the autoresume
setting in nifi.properties to false and restart node(s).
This will bring up every component/controllerService up
stopped/disabled and may provide some breathing room for the UI
to become available again.
Phil
On Mar 22, 2023 at 10:20 AM -0400, Joe Obernberger
<[email protected]>, wrote:
atop shows the disk as being all red with IO - 100%
utilization. There
are a lot of flowfiles currently trying to run through, but I can't
monitor it because....UI wont' load.
-Joe
On 3/22/2023 10:16 AM, Mark Payne wrote:
Joe,
I’d recommend taking a look at garbage collection. It is far
more likely the culprit than disk I/O.
Thanks
-Mark
On Mar 22, 2023, at 10:12 AM, Joe Obernberger
<[email protected]> wrote:
I'm getting "java.net.SocketTimeoutException: timeout" from
the user interface of NiFi when load is heavy. This is 1.18.0
running on a 3 node cluster. Disk IO is high and when that
happens, I can't get into the UI to stop any of the processors.
Any ideas?
I have put the flowfile repository and content repository on
different disks on the 3 nodes, but disk usage is still so
high that I can't get in.
Thank you!
-Joe
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