MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 scanStop listeners added. Use emitter.setMaxListeners() to increase limit #22

General
21

Agree, but in my case I really need Subflow because of the UI that abstract a lot of things.

I tried to put the "WebSocket Out" node outside of the SubSubSubflow and it works ! I no longer have the Warning emitter.setMaxListener() but it is not a solution.

Because I can't create a link node into my SubSubSubflow to target a node that would call the WebSocket node. In you case it works because you are using only Flow

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image1044Ɨ792 78 KB

To my knowledge there is no "Hack" or exposed API to call a Node1 from a Node2 explicilty ?

(For another case, I did something very cool with a callback function that let jump to another node)

22

There is. As already explained, the LinkCall / LinkOut core nodes provide this functionality.
It's setup like this:

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image1048Ɨ528 37.2 KB

Flow:

[
    {
        "id": "5ea31b0cb5dea699",
        "type": "tab",
        "label": "Flow 9",
        "disabled": false,
        "info": "",
        "env": [],
        "_mcu": {
            "mcu": false
        }
    },
    {
        "id": "e2e2f772a1eff8f6",
        "type": "inject",
        "z": "5ea31b0cb5dea699",
        "name": "",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "payload": "10",
        "payloadType": "num",
        "_mcu": {
            "mcu": false
        },
        "x": 170,
        "y": 180,
        "wires": [
            [
                "e94b8d48fd6572be"
            ]
        ]
    },
    {
        "id": "e94b8d48fd6572be",
        "type": "link call",
        "z": "5ea31b0cb5dea699",
        "name": "",
        "links": [
            "1944c969ede348f0"
        ],
        "linkType": "static",
        "timeout": "30",
        "_mcu": {
            "mcu": false
        },
        "x": 340,
        "y": 180,
        "wires": [
            [
                "b8df104959731e08"
            ]
        ]
    },
    {
        "id": "1944c969ede348f0",
        "type": "link in",
        "z": "5ea31b0cb5dea699",
        "name": "Call Me",
        "links": [],
        "_mcu": {
            "mcu": false
        },
        "x": 150,
        "y": 360,
        "wires": [
            [
                "de509aa2a88babcc"
            ]
        ],
        "l": true
    },
    {
        "id": "de509aa2a88babcc",
        "type": "function",
        "z": "5ea31b0cb5dea699",
        "name": "payload * 2",
        "func": "msg.payload *= 2;\nreturn msg;",
        "outputs": 1,
        "timeout": 0,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "_mcu": {
            "mcu": false
        },
        "x": 310,
        "y": 360,
        "wires": [
            [
                "ea769cc1776c3305"
            ]
        ]
    },
    {
        "id": "ea769cc1776c3305",
        "type": "link out",
        "z": "5ea31b0cb5dea699",
        "name": "link out 4",
        "mode": "return",
        "links": [],
        "_mcu": {
            "mcu": false
        },
        "x": 435,
        "y": 360,
        "wires": []
    },
    {
        "id": "b8df104959731e08",
        "type": "debug",
        "z": "5ea31b0cb5dea699",
        "name": "=> Debug",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "payload",
        "targetType": "msg",
        "statusVal": "",
        "statusType": "auto",
        "_mcu": {
            "mcu": false
        },
        "x": 500,
        "y": 180,
        "wires": []
    },
    {
        "id": "516b3e5fa463a95c",
        "type": "inject",
        "z": "5ea31b0cb5dea699",
        "name": "",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "payload": "25",
        "payloadType": "num",
        "_mcu": {
            "mcu": false
        },
        "x": 170,
        "y": 240,
        "wires": [
            [
                "4542b0fc3a8073cb"
            ]
        ]
    },
    {
        "id": "4542b0fc3a8073cb",
        "type": "link call",
        "z": "5ea31b0cb5dea699",
        "name": "",
        "links": [
            "1944c969ede348f0"
        ],
        "linkType": "static",
        "timeout": "30",
        "_mcu": {
            "mcu": false
        },
        "x": 340,
        "y": 240,
        "wires": [
            [
                "ce3825622b5df917"
            ]
        ]
    },
    {
        "id": "ce3825622b5df917",
        "type": "debug",
        "z": "5ea31b0cb5dea699",
        "name": "=> Debug",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "payload",
        "targetType": "msg",
        "statusVal": "",
        "statusType": "auto",
        "_mcu": {
            "mcu": false
        },
        "x": 500,
        "y": 240,
        "wires": []
    },
    {
        "id": "58e5a97758e7a7c0",
        "type": "comment",
        "z": "5ea31b0cb5dea699",
        "name": "This behaves like a standard sub-routine",
        "info": "",
        "_mcu": {
            "mcu": false
        },
        "x": 260,
        "y": 320,
        "wires": []
    }
]

No need for any hack! :+1:

23

Thanks but as I explained it do not work in a subflow. You can't call from a Subflow an external Link Node

I find a kludge work around using JS CallBack that works very well.

24

Yes you can.

25

Isn't there an open issue for this? Upgrading from 4.0.2 to 4.0.3 seems to break link calls inside subflows Ā· Issue #4891 Ā· node-red/node-red Ā· GitHub

26

Yes, it is an unfortunate blip - since resolved (v4.0.4 incoming very soon) but 4.0.2 (and every version before, it does work). Also, under the hood, even 4.0.3 works (you have to use msg.target or edit the flow JSON - i.e. its a frontend issue)

1 Like
27

I really need Subflow because of the UI that abstract a lot of things

But you can still abstract it in a 'subroutine' with a link call node and only use the subflow for the UI part that emits all the properties that you need.

28

Install node red 4.0.2 and wait for the bugfix before installing the latest.
Depending on how you installed node-red that may be done using something like
sudo npm install --unsafe-perm node-red@4.0.2
then restarting node-red.

29

It works with latest Node-Red version !
Many Thanks

30

There might be a bug, but I don't have the how-to-reproduce right now.

Sometimes ... after flow manipulation (nothing complexe, just editing JS Function, ...) when I deploy I have a Warning the "Link node do not have target" I set it again and deploy.

It's like if it lost the link somehow. May be, underhood, related to how it loop through the node graph ?

31

Is this related to MaxListenersExceededWarning or something different?

Are you using Link-Call nodes?

Are you using Subflows?

There was a regression in 4.0.3 and 4.0.4 related to link nodes and subflows. fixed in 4.0.5

Release notes here: Releases Ā· node-red/node-red Ā· GitHub

32

It's related in a way it was the suggested workaround to move WebSocket node outside Subflows.

Yes I implemented Link-Call nodes from Subflow to Flow and it works very well and fixed the MaxListenersExceededWarning

There was a regression in 4.0.3 and 4.0.4 related to link nodes and subflows. fixed in 4.0.5

OMG I'm not fast enought ^^
I'll give it a try