Increasing CPU usage over time

Describe Your Problem: I have noticed that homebridge’s cpu consumption is slowly but surely growing over time:

(homebridge is the teal colored, increasing item. dips to 0% are when I have restarted the host pi4)

I was wondering if anyone has seen similar behavior. Not sure if it is connected to homebridge or the homebridge-mqttthing plugin (the only one I am using).

Logs: I have noticed nothing special in the logs, no errors, etc:

[9/3/2020, 4:01:24 AM] [Dishwasher2] Initializing mqttthing accessory...
[9/3/2020, 4:01:24 AM] [livingroom] Initializing mqttthing accessory...
[9/3/2020, 4:01:24 AM] [bedroom] Initializing mqttthing accessory...
[9/3/2020, 4:01:24 AM] [entrydoor] Initializing mqttthing accessory...
[9/3/2020, 4:01:24 AM] [livingsliding] Initializing mqttthing accessory...
Setup Payload:
X-HM://0023OSNLD56PA
Enter this code with your HomeKit app on your iOS device to pair with Homebridge:
                       
    ┌────────────┐     
    │ xxx-xx-xxx │     
    └────────────┘     
                       
[9/3/2020, 4:01:24 AM] Homebridge is running on port 51826.
[9/14/2020, 10:57:16 PM] [HB Supervisor] OS: Linux 5.4.51-v7l+ arm
[9/14/2020, 10:57:16 PM] [HB Supervisor] Node.js v12.18.3 /usr/local/bin/node
[9/14/2020, 10:57:16 PM] [HB Supervisor] Homebridge Path: /usr/local/lib/node_modules/homebridge/bin/homebridge
[9/14/2020, 10:57:16 PM] [HB Supervisor] UI Path: /usr/local/lib/node_modules/homebridge-config-ui-x/dist/bin/standalone.js
[9/14/2020, 10:57:16 PM] [HB Supervisor] Starting Homebridge with extra flags: -I -P /homebridge/node_modules
[9/14/2020, 10:57:16 PM] [HB Supervisor] Started Homebridge v1.1.3 with PID: 406

Homebridge Config:

{
    "mdns": {
        "interface": "192.168.20.19"
    },
    "bridge": {
        "name": "Homebridge",
        "username": "0E:4E:E3:xx:xx:xx",
        "port": 51826,
        "pin": "xxx-xx-xxx"
    },
    "accessories": [
        {
            "accessory": "mqttthing",
            "type": "switch",
            "name": "Front door",
            "url": "mqtt://192.168.20.15:1883",
            "username": "",
            "password": "",
            "topics": {
                "getOn": "homebridge/state/frontdoor",
                "setOn": "homebridge/control/frontdoor"
            },
            "onValue": "on",
            "offValue": "off",
            "logMqtt": false
        },
        {
            "accessory": "mqttthing",
            "type": "switch",
            "name": "Arriving home",
            "url": "mqtt://192.168.20.15:1883",
            "username": "",
            "password": "",
            "topics": {
                "getOn": "homebridge/state/arrivinghome",
                "setOn": "homebridge/control/arrivinghome"
            },
            "onValue": "on",
            "offValue": "off",
            "logMqtt": false
        },
        {
            "accessory": "mqttthing",
            "type": "outlet",
            "name": "Dishwasher2",
            "url": "mqtt://192.168.20.15:1883",
            "mqttOptions": {
                "keepalive": 30
            },
            "mqttPubOptions": {
                "retain": true
            },
            "topics": {
                "getOn": "tasmota/stat/sonoff-dishwasher/POWER",
                "setOn": "tasmota/cmnd/sonoff-dishwasher/power",
                "getOnline": "tasmota/tele/sonoff-dishwasher/LWT",
                "getWatts": {
                    "topic": "tasmota/tele/sonoff-dishwasher/SENSOR",
                    "apply": "return JSON.parse(message).ENERGY.Power;"
                },
                "getVolts": {
                    "topic": "tasmota/tele/sonoff-dishwasher/SENSOR",
                    "apply": "return JSON.parse(message).ENERGY.Voltage;"
                },
                "getAmperes": {
                    "topic": "tasmota/tele/sonoff-dishwasher/SENSOR",
                    "apply": "return JSON.parse(message).ENERGY.Current;"
                }
            },
            "history": "false",
            "logMqtt": false,
            "onValue": "ON",
            "offValue": "OFF",
            "onlineValue": "Online",
            "startPub": {
                "tasmota/cmnd/sonoff-dishwasher/power": ""
            },
            "manufacturer": "ITEAD",
            "model": "Sonoff POW",
            "serialNumber": "XXXXXXXX"
        },
        {
            "accessory": "mqttthing",
            "type": "temperatureSensor",
            "name": "livingroom",
            "url": "mqtt://192.168.20.15:1883",
            "caption": "Living room temperature",
            "topics": {
                "getCurrentTemperature": "homebridge/status/temperature/livingroom"
            }
        },
        {
            "accessory": "mqttthing",
            "type": "temperatureSensor",
            "name": "bedroom",
            "url": "mqtt://192.168.20.15:1883",
            "caption": "Bedroom temperature",
            "topics": {
                "getCurrentTemperature": "homebridge/status/temperature/bedroom"
            }
        },
        {
            "accessory": "mqttthing",
            "type": "contactSensor",
            "name": "entrydoor",
            "url": "mqtt://192.168.20.15:1883",
            "caption": "Entry door",
            "topics": {
                "getContactSensorState": "homebridge/status/contactsensor/entry"
            },
            "integerValue": true
        },
        {
            "accessory": "mqttthing",
            "type": "contactSensor",
            "name": "livingsliding",
            "url": "mqtt://192.168.20.15:1883",
            "caption": "Sliding door",
            "topics": {
                "getContactSensorState": "homebridge/status/contactsensor/livingsliding"
            },
            "integerValue": true
        }
    ],
    "platforms": [
        {
            "name": "Config",
            "port": 80,
            "auth": "none",
            "host": "192.168.20.19",
            "restart": "sudo -n systemctl restart homebridge",
            "sudo": true,
            "log": {
                "method": "systemd"
            },
            "platform": "config"
        }
    ]
}

Screenshots:

Environment:

• Node.js Version: v12.18.3
• NPM Version: v6.14.6
• Homebridge Version: 1.1.3
• Operating System: Docker on a pi4
• Process Supervisor: Docker

[ebaauw]

Without knowing the structure of what homebridge does with its threads I can’t know, but it seems plausible that these four threads correspond to the plugins (they do show an up-tick in CPU when I use them). Note, no huge (or unbalanced) CPU TIME accumulation for these, just the main homebridge process.

The threads are spawned by NodeJS, mainly to do I/O and compute-intensive stuff without blocking the main thread. You’ll see them for any NodeJS application. Homebridge is completely unaware of this, and there’s no relation between a plugin and a thread.

For details, see http://docs.libuv.org/en/v1.x/design.html.

[rbswift]

Do you have both wifi and wired Ethernet connected to the same network? I found this caused problems for me and my CPU creep immediately abated after running ifconfig wlan0 down.

I haven’t investigated further but could be some kind of broadcast/multicast loop happening.