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so I built a script in node.js which supposed to take csv files, parse them and enter them to DB. Sometimes, when I debug my code, it stops on like an invisible breakpoint found in async_hooks.js file, on the first line of the "emitHookFactory" function (line 163).

The call stack states only one call- "emitBeforeNative" on the same file.

I noticed a few things on my trials:

  1. I have 3 types of files I need to parse and put in the DB. It happens only on one of the file types, which is extremely large (3.1m~ lines on csv, while the others have 50~200K lines). I tried to load it partially- only the starting 20K lines (copied them to a new file, no changes in code) and it didn't break. which means the size has to do with the debugger stopping?

  2. I tried to reproduce it with other means but no success. Also, it doesn't happen always (even when ran on the same file)- but like 80-85% of the times.

  3. My script goes like this: query DB and AWS to find a new file > download file to local > stream the file from local > on line event- parse line and perform data manipulations > on end event - loop through all manipulated data, build queries and query the DB to insert it. I've put a few breakpoints on key places and found out the breakpoint SEEMS to happen somewhere in the middle of emitting the line events. The callback function is a normal function, not async, and there are no async operations inside. In fact, there are only array and string manipulations operations inside- not even 3rd party operation or anything unusual.

  4. I tried to look at the internet for solution. Didn't find any clear way to comletely get rid of it, only workaround which I didn't really understand (kinda new to JS environments so I could not get the concepts of how can I disable or ignore it...)

Thanks for the help in advanced.

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  • VS Code shows the "reason" for breaking into the debugging in the header of the CALL STACK view. What does it say in your case? Commented Aug 6, 2019 at 10:39
  • I found this bug report which breaks in the same location github.com/shd101wyy/mume/issues/70. One commenter said "some exception in a promise that's hard to track." Are you using promise based API anywhere? Are you handling errors correctly? Do you have Caught or Uncaught Exceptions checked in VS Code's BREAKPOINTS view? Does it make a difference if you toggle those settings? Commented Aug 6, 2019 at 10:50
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    @AndreWeinand sorry for the late answer, it took me some time till my DB was free for my tests again. It says simply: "paused on debugger statement"... god knows what that means. I am using promise based API, and I got both "all exceptions" and "uncaught exceptions" marked. It doesn't make any difference tho, because the code doesn't crash. It just stopped as if there was a breakpoint there, and when I press f5 it continues as usual (unless im waiting too long and my DB connection times out, but code is stopped on "BP" and can't execute my handleDisconnection method so it crushes). Commented Aug 7, 2019 at 9:37
  • "paused on debugger statement" means that the node.js runtime thinks it is stopped on a literal "debugger;" statement in the code. Commented Aug 8, 2019 at 10:22
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    @AndreWeinand any more ideas? this bug still annoys me and hell and I can't get rid of it... I got a script running for 3.5 hrs and every time I wanna do a check run I have to sit next to it for like 40min so I can press f5 when it gets stuck and let it continue Commented Aug 20, 2019 at 11:48

2 Answers 2

Reset to default
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Based on https://github.com/nodejs/node/issues/15464

There's a way to ignore stepping into Node guts. In your launch.json add the following skipFiles directive:

"skipFiles": [
    "<node_internals>/**"
]

or you can ignore particularly /internal/async_hooks with this:

"skipFiles": [
    "<node_internals>/internal/async_hooks.js",
    "<node_internals>/internal/inspector_async_hook.js"
]

After all, your config may look like this:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "pwa-node",
            "request": "launch",
            "name": "Debug",
            "runtimeExecutable": "<your executable path>",
            "console": "integratedTerminal",
            "cwd": "${workspaceFolder}",
            "timeout": 30000,
            "skipFiles": [
                "<node_internals>/**"
            ]
        }
    ]
}

This also might be related to a known NodeJS bug: https://github.com/nodejs/node/issues/36022

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Comments

-1

Could you please try whether our new JavaScript debugger still has this problem. For details see the release notes of VS Code 1.42: https://code.visualstudio.com/updates/v1_42#_new-javascript-debugger.

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1 Comment

As of 10th March 2021, this is still the case even when using this debugger

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