[LanguageWorker][Debugging]Function Host fails to restart language worker process on file edit if debugger is attached

[pavanagrawal123]

I'm launching the debugger from VSCode. The run time is v2, and language is Node.js.

Every time I make a change to the file, the debug process crashes and I have to start the function again, as well as the debug session.

• Function App version (1.0 or 2.0): 2.0
• Function App name: runnning locally

I'm on Windows!

Repro steps

1. Download VSCode
2. Install Node.js
3. Install the Azure Functions Runtime
4. Create a function
5. Launch a debug session
6. Make a change to function, save file, see crash.

Expected behavior

I don't expect the function runtime to crash.

Here's a sample log from when it happens:

info: Host.General[0]
     Restarting host.
info: Host.General[0]
     Building host: startup suppressed:False, configuration suppressed: False
info: Host.Startup[0]
     Reading host configuration file 'C:\volunteerManagement\host.json'
info: Host.Startup[0]
     Host configuration file read:
     {
       "version": "2.0"
     }
[10/1/2018 7:00:19 PM] Initializing Host.
[10/1/2018 7:00:19 PM] Host initialization: ConsecutiveErrors=0, StartupCount=2
[10/1/2018 7:00:19 PM] Starting JobHost
[10/1/2018 7:00:19 PM] Starting Host (HostId=desktoplglnm4m-1873661633, InstanceId=aada58ee-e906-47b5-bde3-669548211425, Version=2.0.12115.0, ProcessId=4536, AppDomainId=1, Debug=False, FunctionsExtensionVersion=)
[10/1/2018 7:00:19 PM] Starting language worker process:node  --inspect=5858 "C:\Users\Admin\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\node\dist/src/nodejsWorker.js" --host 127.0.0.1 --port 49634 --workerId 40137e5e-1db2-4007-9067-57bcd26ecfb2 --requestId 2fdb954b-ba34-4ac7-862c-d785b047d56b --grpcMaxMessageLength 134217728
[10/1/2018 7:00:19 PM] node process with Id=7328 started
[10/1/2018 7:00:19 PM] Generating 4 job function(s)
[10/1/2018 7:00:19 PM] Found the following functions:
[10/1/2018 7:00:19 PM] Host.Functions.getEventsForRegistration
[10/1/2018 7:00:19 PM] Host.Functions.getIfCurrent
[10/1/2018 7:00:19 PM] Host.Functions.registerMember[10/1/2018 7:00:19 PM] Starting inspector on 127.0.0.1:5858 failed: address already in use

[10/1/2018 7:00:19 PM] Host.Functions.signupEvent
[10/1/2018 7:00:19 PM]
[10/1/2018 7:00:19 PM] Language Worker Process exited.
[10/1/2018 7:00:19 PM] Host initialized (278ms)
[10/1/2018 7:00:19 PM] node exited with code 12
.
[10/1/2018 7:00:19 PM] Host started (288ms)
[10/1/2018 7:00:19 PM] Job host started
[10/1/2018 7:00:19 PM] Starting language worker process:node  --inspect=5858 "C:\Users\Admin\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\node\dist/src/nodejsWorker.js" --host 127.0.0.1 --port 49634 --workerId cc3e30e5-2c72-40f7-baa3-e685c0c2adfc --requestId ad1b93ad-e6aa-4021-a66c-1bd7cd8498e3 --grpcMaxMessageLength 134217728
[10/1/2018 7:00:19 PM] node process with Id=22756 started
[10/1/2018 7:00:19 PM] Stopping JobHost
[10/1/2018 7:00:19 PM] Job host stopped
info: Host.General[0]
     Host restarted.
[10/1/2018 7:00:19 PM] Language Worker Process exited.[10/1/2018 7:00:19 PM] Debugger listening on ws://127.0.0.1:5858/ac861383-518f-451b-affe-65d33b3c5d73

[10/1/2018 7:00:20 PM] node exited with code -1
.
[10/1/2018 7:00:20 PM] For help, see: https://nodejs.org/en/docs/inspector
[10/1/2018 7:00:20 PM] Worker cc3e30e5-2c72-40f7-baa3-e685c0c2adfc connecting on 127.0.0.1:49634
[10/1/2018 7:00:24 PM] Host lock lease acquired by instance ID '0000000000000000000000004C66A269'.

[mhoeger]

The root cause is issue #3415

[pragnagopa]

Are you seeing this when you are changing file and saving it while the debugger is attached?

[pavanagrawal123]

Yes, that's exactly where I'm seeing the issue

[graysonwebster]

I'm also seeing this issue.

[rhummelmose]

Any update on when this'll be fixed? Makes it hard to follow a real flow of work

[rhummelmose]

For anybody who may have an interest in how to get a decent workflow up and running in VSCode until this issue is resolved I've put the following together to allow me to automatically start/stop the functions host when I launch the debugger.

launch.json

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "type": "node",
            "request": "attach",
            "name": "Run Functions host and attach",
            "protocol": "inspector",
            "preLaunchTask": "Compile TS, Run Functions (Shell)",
            "postDebugTask": "Stop Functions",
            "outFiles": [ "{workspaceRoot}/TypeScriptFunction/index.js" ],
            "port": 5858
        },
        {
            "type": "node",
            "request": "attach",
            "name": "Attach",
            "protocol": "inspector",
            "outFiles": [ "{workspaceRoot}/TypeScriptFunction/index.js" ],
            "port": 5858
        }
    ]
}

tasks.json

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "Run Functions",
      "type": "shell",
      "command": "sh scripts/functions_host_background.sh",
      "problemMatcher": []
    },
    {
      "label": "Stop Functions",
      "type": "shell",
      "command": "tmux kill-session -t azure-functions-playground",
      "problemMatcher": []
    },
    {
      "label": "Compile TypeScript",
      "type": "shell",
      "command": "tsc --outDir TypeScriptFunction --sourceMap --lib es2015 TypeScriptFunction/index.ts",
      "problemMatcher": []
    },
    {
      "label": "Compile TS, Run Functions (Compound)",
      "type": "shell",
      "dependsOn": [
        "Compile TypeScript",
        "Run Functions"
      ],
      "problemMatcher": []
    },
    {
      "label": "Compile TS, Run Functions (Shell)",
      "type": "shell",
      "command": "tsc --outDir TypeScriptFunction --sourceMap --lib es2015 TypeScriptFunction/index.ts;sh scripts/functions_host_background.sh",
      "problemMatcher": []
    }
  ]
}

functions_host_background.sh

tmux kill-session -t azure-functions-playground
tmux start-server
tmux new-session -d -s azure-functions-playground -n host
tmux send-keys -t azure-functions-playground:host "func host start --language-worker -- \"--inspect=5858\"" C-m

You need tmux, but it makes life bearable..

Add the presentation options to your tasks to keep them out of sight.

I couldn't use the compound key because of this bug: microsoft/vscode#52737

[tsuga]

I have the same issue, and am hoping this will be fixed soon.

[IMAMBAKS]

I have the same issue... Please fix this asap...