# "Rate detection" - can it be done "easily"?

**URL:** <https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188>\
**Category:** General\
**Created:** [3 April 2020 21:41 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188 "2020-04-03T21:41:52Z")\
**Posts on this page:** 11\
**Page:** 1

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**Author:** ![Trying\_to\_learn](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/trying_to_learn/32/28400_2.png) [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Post date:** [3 April 2020 21:41 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/1 "2020-04-03T21:41:52Z")

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Sort of from my other post about finding the error,

The problem is still a bit unknown to what happened.

It is now possible it was on another machine and the error handling parts of the flow went into overdrive. ☹

So, as a possible bit of help, I was wondering if this idea would be possible:

I know there is a way to limit the rate of message passing, with the `delay` node.  
B-u-t....

Is there a way (easy) so: all things being good all messages are passed.  
If there is a spike where the messages are _climbing over one another_ that a threshold is exceeded and a signal sent?

That signal would _shut a gate_ and stop the possible feedback loop.

Open to ideas on how to do that.  
And if it is really viable.

I am looking at it because a couple of times I have spent/lost a lot of time in the _error handling_ parts of the flows.  
When an error happens in them: all hell breaks loose.

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**Author:** ![realjax](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/realjax/32/895_2.png) [@realjax](https://discourse.nodered.org/u/realjax)\
**Post date:** [4 April 2020 17:09 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/2 "2020-04-04T17:09:27Z")

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Write a function that counts the number of messages received per minute or per 5 minutes. If it exceeds a certain average then continue the flow and send a notification.

Mind you, it seems smelly to me and you are better off catching the error in some way.

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**Author:** ![drmibell](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/drmibell/32/8424_2.png) [@drmibell](https://discourse.nodered.org/u/drmibell)\
**Post date:** [4 April 2020 17:42 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/3 "2020-04-04T17:42:19Z")

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> [@realjax](#):
>
> a function that counts the number of messages received per minute

Slightly OT: many devices and systems take this approach, but it's generally better to measure and average the interval between messages. There are good theoretical reasons for this, but the practical one is that you can get either a faster indication of rate changes or a longer averaging time very easily.

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<div class="post-metadata">

**Author:** ![realjax](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/realjax/32/895_2.png) [@realjax](https://discourse.nodered.org/u/realjax)\
**Post date:** [4 April 2020 18:43 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/4 "2020-04-04T18:43:45Z")

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Yes, I'd probably calculate an average on each message received which means it could trigger as soon as the threshold is met.

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [4 April 2020 21:41 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/5 "2020-04-04T21:41:17Z")

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There is also this node - [https://flows.nodered.org/node/node-red-contrib-msg-speed](https://flows.nodered.org/node/node-red-contrib-msg-speed) - that may help give you a message rate which you could use to trigger a switch if too great etc.

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<div class="post-metadata">

**Author:** ![Trying\_to\_learn](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/trying_to_learn/32/28400_2.png) [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Post date:** [4 April 2020 21:59 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/6 "2020-04-04T21:59:18Z")

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(I'll get to the other replies next)

> [@realjax](#):
>
> Mind you, it seems smelly to me and you are better off catching the error in some way.

Yeah, I know.

But when you have a `catch` node and code to decode the error and **that** code has an error things get messy very VERY quickly.

You get 80 errors in one second.

> [@realjax](#):
>
> per minute or per 5 minutes.

Per minute (or 5) would be pointless.

The machine is nearly dead in the water after 20 seconds.  
(80 x 20 = 2000)

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<div class="post-metadata">

**Author:** ![Trying\_to\_learn](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/trying_to_learn/32/28400_2.png) [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Post date:** [4 April 2020 22:02 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/7 "2020-04-04T22:02:56Z")

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Thanks!

That looks promising.

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<div class="post-metadata">

**Author:** ![hominidae](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hominidae/32/4174_2.png) [@hominidae](https://discourse.nodered.org/u/hominidae)\
**Post date:** [5 April 2020 12:21 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/8 "2020-04-05T12:21:49Z")

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...if the msg flood with errors are all of the same content, why - in addition to using a gate note to stop the cause of the problem - discard at least the ones already in the system for relief?  
Have you seen this? -\> [https://flows.nodered.org/flow/9410e4cebcc4b68fae73](https://flows.nodered.org/flow/9410e4cebcc4b68fae73)

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<div class="post-metadata">

**Author:** ![Trying\_to\_learn](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/trying_to_learn/32/28400_2.png) [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Post date:** [5 April 2020 23:59 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/9 "2020-04-05T23:59:01Z")

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You seem to be missing what I want to do.

Here is an **example** of what I had.

Go on, press the `PRESS ME` button!

```auto
[{"id":"9622ad2c.d38ad","type":"catch","z":"b4f1ccd4.5e8d1","name":"","scope":null,"uncaught":false,"x":190,"y":960,"wires":[["bcc89445.e48528","9039d6f0.c8fde8"]]},{"id":"bcc89445.e48528","type":"template","z":"b4f1ccd4.5e8d1","name":"","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"You have an error {{error.message}} !","output":"str","x":360,"y":960,"wires":[["5e8d9d8f.d6e79c"]]},{"id":"9039d6f0.c8fde8","type":"function","z":"b4f1ccd4.5e8d1","name":"Read the description for this node.","func":"var n = 23 + 56 / a;\n//var n = 23 + 56 ;\nmsg.payload = n;\nreturn msg;","outputs":1,"noerr":0,"x":430,"y":1010,"wires":[[]],"info":"ONLY for the sake of making an error.\n\nThe code is not \"real\".\n\nIt is only to show you what was happening."},{"id":"5e8d9d8f.d6e79c","type":"debug","z":"b4f1ccd4.5e8d1","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":540,"y":960,"wires":[]},{"id":"17cd6530.85b393","type":"inject","z":"b4f1ccd4.5e8d1","name":"PRESS ME!","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":180,"y":1010,"wires":[["9039d6f0.c8fde8"]]}]

```

Explain how putting a rate limit will fix the problem.

There is/was/could be an error.

If it is a normal error, I want to know _who_ created it, etc.

If it is in the routine which detects the error, it is a whole different ball game.

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<div class="post-metadata">

**Author:** ![hominidae](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hominidae/32/4174_2.png) [@hominidae](https://discourse.nodered.org/u/hominidae)\
**Post date:** [6 April 2020 17:50 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/10 "2020-04-06T17:50:45Z")

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Yes, I missed that...OK, I see...thanks for sharing

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [20 April 2020 17:50 UTC](https://discourse.nodered.org/t/rate-detection-can-it-be-done-easily/24188/11 "2020-04-20T17:50:50Z")

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