# Node.send not always works

**URL:** <https://discourse.nodered.org/t/node-send-not-always-works/60615>\
**Category:** Developing Nodes\
**Created:** [31 March 2022 19:35 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615 "2022-03-31T19:35:54Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [31 March 2022 19:35 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/1 "2022-03-31T19:35:54Z")

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I am developing a node that receives asynchronous messages from an external system through AMQP and sends the data to the developed node output.

My external message function is triggered perfectly fine every time, but when I call `node.send` with the created node-red message. It is not always sent (I am testing it with a Debug node, or with another custom node).

The more nodes of this type I have, the percentage of undelivered output messages from all of the is getting higher.

What should be the way to debug it?  
Thanks

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [31 March 2022 19:50 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/2 "2022-03-31T19:50:52Z")

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In your function add a `node.warn()` statement immediately before the `node.send()` That will output a message in the node red log. Also configure the debug node to output to the console, so that will also appear in the log. Then run your flow and look in the log to see if you see node-warn outputs without the corresponding debug. Note that the warn and the debug may be separated as, if the function loops with multiple sends then they will all appear before the debug output, so they will have to have an identifiable content in order to link them up.

Also tell us what version of node-red and of nodejs you are using and what hardware/OS you are running on.

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [31 March 2022 20:32 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/3 "2022-03-31T20:32:57Z")

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The function does not loop the sends (just one send per externally received message) every 5 seconds. The size of the message is pretty big - ~5kb.

I did this scenario precisely (printing `node.warn` with a message id after `node.send`).  
I do see `node.warn` log for 100% of the cases but the debug log for less than 50%.  
I use node-red 2.2.2 with node v14.19.0, on Ubuntu 20.04 development machine

Thanks!

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [31 March 2022 20:41 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/4 "2022-03-31T20:41:34Z")

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Is it possible that the object you are attempting to send is null? Or perhaps you are repeatedly sending the same object. If you do that and the object gets sets to null then the previous one sent will also become null.

Otherwise are you able to construct a test flow we can run to see the problem?  
If not then can you post the code of the function?

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [31 March 2022 21:14 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/5 "2022-03-31T21:14:34Z")

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Or in fact if you did

```auto
node.send(msg)
// some code
msg = null

```

then by the time the debug node receives it then it may be null. You must not do anything with msg after you send it.

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<div class="post-metadata">

**Author:** ![knolleary](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/knolleary/32/3_2.png) [@knolleary](https://discourse.nodered.org/u/knolleary)\
**Post date:** [31 March 2022 22:04 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/6 "2022-03-31T22:04:55Z")

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> [@Colin](#):
>
> then by the time the debug node receives it then it may be null. You must not do anything with msg after you send it.

In this instance, setting `msg` to `null` will not modify anything downstream as it is reassigning what the local variable `msg` points at, rather than modifying the contents of what `msg` pointed at.

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [1 April 2022 08:57 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/7 "2022-04-01T08:57:44Z")

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That is true. The contents of msg could be corrupted, but not msg itself.  
Perhaps msg is null before the node.send() call then.

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [1 April 2022 17:25 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/8 "2022-04-01T17:25:49Z")

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I am defining the `msg` with `var msg = [];` and adding content with `msg.push`. `node.send` is the last instruction in the function except `node.warn` printout. The printout prints the size of the message (`${JSON.stringify(msg).length}`) so it's certainly not `null`.

The problem is not that debug node receives a `null` message, the problem is that it receives every second or third message only. I double tested it with another custom node by manually printing the input into the console.

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [1 April 2022 17:44 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/9 "2022-04-01T17:44:32Z")

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> [@cloud-rocket](#):
>
> I am defining the `msg` with `var msg = [];` and adding content with `msg.push` . `node.send` is the last instruction in the function except `node.warn` printout. The printout prints the size of the message ( `${JSON.stringify(msg).length}` ) so it's certainly not `null`

If you send an array to `node.send`, then it attempts to send each entry in the array to each output pin of your node. The fact your array length is \> 0 is irrelevant.

Console log the full `msg` array and show us the actual content.

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [1 April 2022 20:15 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/10 "2022-04-01T20:15:51Z")

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Please explain what your intention is when you send an array.

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [4 April 2022 17:08 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/11 "2022-04-04T17:08:35Z")

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> If you send an array to `node.send` , then it attempts to send each entry in the array to each output pin of your node. The fact your array length is \> 0 is irrelevant.
> 
> Console log the full `msg` array and show us the actual content.

This is the message as it appears after `node.send` call:

```auto
[
  {
    topic: 'combined_sample',
    msg_id: 67829,
    payload: {
      sensor1: -25,
      sensor2: -7.5,
      sensor3: -12,
      ... (160 sensors)
    },
    timestamp: '2022-04-04 16:25:25.922000+00:00',
    _msgid: 'c1db56467e7a9218'
  }
]

```

It is not always delivered.

`_msgid: 'c1db56467e7a9218'` is generated by `node.send` even if the message is not delivered.

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [4 April 2022 17:10 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/12 "2022-04-04T17:10:20Z")

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> [@Colin](#):
>
> Please explain what your intention is when you send an array.

Sometimes I need to send more than a single message during the same call. Messages are not delivered regardless if it's one or more messages sent together.

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [4 April 2022 17:19 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/13 "2022-04-04T17:19:28Z")

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I am using `amqp-connection-manager` package which is based on `amqplib`:

My AMQP message subscription code is based on [this example](https://github.com/jwalton/node-amqp-connection-manager/blob/master/examples/pubsub-subscriber.js).

The `onMessage` function is where the `node.send` called from.

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [4 April 2022 17:47 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/14 "2022-04-04T17:47:38Z")

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It's not (to me) 100% clear where you are losing messages. I can say with absolute certainty that node.send is reliable and will not be discarding messages from your array unless they are empty/Null.

where is this array of messages being sent from? From your custom node? Or from a function node in your flow?

Do you have a repository on line where I can view your code & ora flow that demonstrates this issue?

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [4 April 2022 17:52 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/15 "2022-04-04T17:52:26Z")

</div>

`node.send` is called from my custom node. I added debug prints to `Node.prototype.send = function(msg)` within `node_modules/@node-red/runtime/lib/nodes/Node.js` and it always finishes (it's not returning on error at the beginning).

So the message is not delivered somewhere else (on another node receive maybe?).

Any idea where to look?

I also suspect it is happening when more than a single node of this custom type is used.

(the code is not public so cannot publish)

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**Author:** ![cymplecy](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cymplecy/32/2773_2.png) [@cymplecy](https://discourse.nodered.org/u/cymplecy)\
**Post date:** [4 April 2022 20:17 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/16 "2022-04-04T20:17:48Z")

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> [@cloud-rocket](#):
>
> (the code is not public so cannot publish)

That's going to make it tricky to help you

Unless your prepared to pay someone commercial rates and sign an NDA of course

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [4 April 2022 21:09 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/17 "2022-04-04T21:09:34Z")

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The behavior is even weirder:

The 1st time I am starting the node-red (from command line with `nodemon`) - all the messages arrive. If I restart the flow (from the web menu) - every second message arrives. Restart once again - every 3rd message arrives and so on....

Any clue?

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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 2022 22:12 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/18 "2022-04-04T22:12:52Z")

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you are not cleaning up whatever listeners you have added when the node is closed (called on deploy) ?

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [4 April 2022 22:20 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/19 "2022-04-04T22:20:10Z")

</div>

> you are not cleaning up whatever listeners you have added when the node is closed (called on deploy) ?

What exactly should I clean on node-red side? I do receive all the external messages after every restart. If I enable "metrics" options in `settings.json` I do see that message is sent from one node (my custom node), but not always received on another (debug) node.

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**Author:** ![cloud-rocket](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cloud-rocket/32/48745_2.png) [@cloud-rocket](https://discourse.nodered.org/u/cloud-rocket)\
**Post date:** [5 April 2022 17:41 UTC](https://discourse.nodered.org/t/node-send-not-always-works/60615/20 "2022-04-05T17:41:38Z")

</div>

> you are not cleaning up whatever listeners you have added when the node is closed (called on deploy) ?

It indeed looks like some kind of a cleanup problem - after a restart all messages are sent twice, after 2 restarts 3 times, and so on..... (I discovered it by enabling preRoute hook)

[Next page](https://discourse.nodered.org/t/node-send-not-always-works/60615.md?page=2)