Nodemon restarts twice on file changes

[isidorn]

Refs: #48423

1. Have a simple nodemon setup, using a nodemon sample
2. Start debugging that sample and hit a breakpoint
3. Make a change to that file and save
4. Notice the session properly restars however it seems to restart twice

[weinand]

@roblourens This problem only occurs for "inspector" protocol.
And it was already broken in the Stable 1.22.2 release.

It seems to be a timing issue because it is almost impossible to reproduce when running in Dev Tools.

Here is the result of my tracing what's going on on the VS Code side (in rawDebugSession).
The initial number is an ID of the rawDebugSession (and the associated DA).

"legacy" works fine:

1: launch request (undefined)
<modify source>
1: terminated event (restart:{"restart":{"port":25168}})
1: disconnect request(restart:true)
1: exited event
2: launch request ({"port":25168})

"inspector" mostly works fine too when running it in Dev Tools:

1: launch request (undefined)
<modify source>
1: terminated event (restart:{"restart":{"port":28026}})
1: disconnect request(restart:true)
1: exited event
2: launch request ({"port":28026})

but sometimes "inspector" results in the debuggee launched twice:

1: launch request (undefined)
<modify source>
1: terminated event (restart:{"restart":{"port":15521}})
1: disconnect request(restart:true)
1: exited event
2: launch request ({"port":15521})
2: terminated event (restart:{"restart":{"port":15521}})   <--- the problem
2: disconnect request(restart:true)
2: exited event
3: launch request ({"port":15521})

The problem is the unexpected terminated event (see arrow) but I have no clue why this happens...
Maybe node-debug2 tries to attach too early, which fails and results in the terminated event.

I debugged node-debug2 a bit but I could not find the reason for the early Terminate event.

[roblourens]

I can't repro any problem with nodemon... was this fixed by any of the debug changes last week?

[weinand]

@isidorn since I did not change anything, did you?

[isidorn]

I can still reproduce this with the following javascript file

console.log('hey2');

And with the following configuration

{
            "type": "node",
            "request": "launch",
            "name": "nodemon",
            "runtimeExecutable": "nodemon",
            "program": "${workspaceFolder}/hey.js",
            "restart": true,
            "console": "integratedTerminal",
            "internalConsoleOptions": "neverOpen"
        }

[roblourens]

I guess I'm doing something wrong. Is this the right scenario? What does "restart twice" mean?

[isidorn]

@roblourens yes you are doing everything fine.
Restart twice means the debug toolbar blinks 2 times in practice. In your demo it blinks only once.

I have node version 8.9.1 and nodemon 1.11.0
Should I update something.
Can I debug this somehow on my machine so you get the needed info?