Ok.. I just tried disconnecting each node from the cluster, in turn.  The
first three (prod-6, -7, and -8) didn't make a difference, but when I
reconnected prod-5, the load balanced connection started flowing again.

I'll continue to monitor it and let you know if this happens again.

Thanks for the suggestions!

On Tue, Jun 4, 2019 at 4:14 PM Joe Gresock <[email protected]> wrote:

> prod-5 and -6 don't appear to be receiving any data in that queue, based
> on the status history.  Is there anything I should see in the logs to
> confirm this?
>
> On Tue, Jun 4, 2019 at 4:05 PM Mark Payne <[email protected]> wrote:
>
>> Joe,
>>
>> So it looks like from the Diagnostics info, that there are currently 500
>> FlowFiles queued up.
>> They all live on prod-8.ec2.internal:8443. Of those 500, 250 are waiting
>> to go to prod-5.ec2.internal:8443,
>> and 250 are waiting to go to prod-6.ec2.internal:8443.
>>
>> So this tells us that if there are any problems, they are likely
>> occurring on one of those 3 nodes. It's also not
>> related to swapping if it's in this state with only 500 FlowFiles queued.
>>
>> Are you able to confirm that you are indeed receiving data from the load
>> balanced queue on both prod-5 and prod-6?
>>
>>
>> On Jun 4, 2019, at 11:47 AM, Joe Gresock <[email protected]> wrote:
>>
>> Thanks Mark.
>>
>> I'm running on Linux.  I've followed your suggestion and added an
>> UpdateAttribute processor to the flow, and attached the diagnostics for it.
>>
>> I also don't see any errors in the logs.
>>
>> On Tue, Jun 4, 2019 at 3:34 PM Mark Payne <[email protected]> wrote:
>>
>>> Joe,
>>>
>>> The first thing that comes to mind would be NIFI-6285, as Bryan points
>>> out. However,
>>> that only would affect you if you are running on Windows. So, the first
>>> question is:
>>> what operating system are you running on? :)
>>>
>>> If it's not Windows, I would recommend getting some diagnostics info if
>>> possible. To do this,
>>> you can go to 
>>> http://<hostname>:<port>/nifi-api/processors/<processor-id>/diagnostics.
>>> For example,
>>> if you get to nifi by going to http://nifi01:8080/nifi, and you want
>>> diagnostics for processor with ID 1234,
>>> then try going to
>>> http://nifi01:8080/nifi-api/processors/1234/diagnostics in your browser.
>>>
>>> But a couple of caveats on the 'diagnostics' approach above. It will
>>> only work if you are running an insecure
>>> NiFi instance, or if you are secured using certificates. We want the
>>> diagnostics for the Processor that is either
>>> the source of the connection or the destination of the connection - it
>>> doesn't matter which. This will give us a
>>> lot of information about the internal structure of the connection's
>>> FlowFile Queue. Of course, you said that your
>>> connection is between two Process Groups, which means that neither the
>>> source nor the destination is a Processor,
>>> so I would recommend creating a dummy Processor like UpdateAttribute and
>>> temporarily dragging the Connection
>>> so that it points to that Processor, just to get the diagnostic
>>> information, then dragging the connection back.
>>>
>>> Of course, it would also be helpful to look for any errors in the logs.
>>> But if you are able to get the diagnostics info
>>> as described above, that's usually the best bet for debugging this sort
>>> of thing.
>>>
>>> Thanks
>>> -Mark
>>>
>>>
>>> On Jun 4, 2019, at 11:13 AM, Bryan Bende <[email protected]> wrote:
>>>
>>> Joe,
>>>
>>> There are two known issues that possibly seem related...
>>>
>>> The first was already addressed in 1.9.0, but the reason I mention it
>>> is because it was specific to a connection between two ports:
>>>
>>> https://issues.apache.org/jira/browse/NIFI-5919
>>>
>>> The second is not in a release yet, but is addressed in master, and
>>> has to do with swapping:
>>>
>>> https://issues.apache.org/jira/browse/NIFI-6285
>>>
>>> Seems like you wouldn't hit the first one since you are on 1.9.2, but
>>> does seem odd that is the same scenario.
>>>
>>> Mark P probably knows best about debugging, but I'm guessing possibly
>>> a thread dump while in this state would be helpful.
>>>
>>> -Bryan
>>>
>>> On Tue, Jun 4, 2019 at 10:56 AM Joe Gresock <[email protected]> wrote:
>>>
>>>
>>> I have round robin load balanced connections working on one cluster, but
>>> on another, this type of connection seems to be stuck.
>>>
>>> What would be the best way to debug this problem?  The connection is
>>> from one processor group to another, so it's from an Output Port to an
>>> Input Port.
>>>
>>> My configuration is as follows:
>>> nifi.cluster.load.balance.host=
>>> nifi.cluster.load.balance.port=6342
>>> nifi.cluster.load.balance.connections.per.node=4
>>> nifi.cluster.load.balance.max.thread.count=8
>>> nifi.cluster.load.balance.comms.timeout=30 sec
>>>
>>> And I ensured port 6342 is open from one node to another using the
>>> cluster node addresses.
>>>
>>> Is there some error that should appear in the logs if flow files get
>>> stuck here?
>>>
>>> I suspect they are actually stuck, not just missing, because the
>>> remainder of the flow is back-pressured up until this point in the flow.
>>>
>>> Thanks!
>>> Joe
>>>
>>>
>>>
>>
>> --
>> I know what it is to be in need, and I know what it is to have plenty.  I
>> have learned the secret of being content in any and every situation,
>> whether well fed or hungry, whether living in plenty or in want.  I can
>> do all this through him who gives me strength.    *-Philippians 4:12-13*
>> <diagnostics.json.gz>
>>
>>
>>
>
> --
> I know what it is to be in need, and I know what it is to have plenty.  I
> have learned the secret of being content in any and every situation,
> whether well fed or hungry, whether living in plenty or in want.  I can
> do all this through him who gives me strength.    *-Philippians 4:12-13*
>


-- 
I know what it is to be in need, and I know what it is to have plenty.  I
have learned the secret of being content in any and every situation,
whether well fed or hungry, whether living in plenty or in want.  I can do
all this through him who gives me strength.    *-Philippians 4:12-13*

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