Breakpoint does not work on Node.js modules

[ugultopu]

• Node.js Version: v15.0.1
• OS: macOS
• Scope (install, code, runtime, meta, other?): code, debugging
• Module (and version) (if relevant): Stream but I don't think module is important

I have the following code:

basic-stream.js:

const readStream = require('stream').Readable();
readStream.push('beep ');

I run it with node inspect basic-stream.js, open my browser, open developer tools and click on the "Open dedicated DevTools for Node.js" button. This launches a new window for debugging my application.

I'm able to step through the code just fine. I can step into a function call and the debugger will go to the line where the function is, even if the function is a Node.js library.

I'm also able to put a breakpoint to somewhere in my code and when I click on "Resume script execution", the code will stop on the breakpoint.

However, when I try to insert a breakpoint in a Node.js library and then click on "Resume script execution", the breakpoint will not be hit, even though the execution will go through that point:

What's the problem here? How can I fix this?

[ugultopu]

It doesn't work from the command line debugger either. I get "Could not resolve breakpoint - undefined" error when I try to set the breakpoint:

$ node inspect basic-stream.js 
< Debugger listening on ws://127.0.0.1:9229/d694952c-7819-45d6-bdac-e0c1541553d7
< For help, see: https://nodejs.org/en/docs/inspector
< Debugger attached.
Break on start in basic-stream.js:1
> 1 const readStream = require('stream').Readable();
  2 readStream.push('beep ');
  3 
debug> setBreakpoint(2)
  1 const readStream = require('stream').Readable();
> 2 readStream.push('beep ');
  3 
debug> cont
break in basic-stream.js:2
  1 const readStream = require('stream').Readable();
> 2 readStream.push('beep ');
  3 
debug> step
break in node:internal/streams/readable:218
 216 // write() some more.
 217 Readable.prototype.push = function(chunk, encoding) {
>218   return readableAddChunk(this, chunk, encoding, false);
 219 };
 220 
debug> step
break in node:internal/streams/readable:227
 225 
 226 function readableAddChunk(stream, chunk, encoding, addToFront) {
>227   debug('readableAddChunk', chunk);
 228   const state = stream._readableState;
 229 
debug> list()
 222 Readable.prototype.unshift = function(chunk, encoding) {
 223   return readableAddChunk(this, chunk, encoding, true);
 224 };
 225 
 226 function readableAddChunk(stream, chunk, encoding, addToFront) {
>227   debug('readableAddChunk', chunk);
 228   const state = stream._readableState;
 229 
 230   let err;
 231   if (!state.objectMode) {
 232     if (typeof chunk === 'string') {
debug> setBreakpoint(230)
Uncaught Error: Could not resolve breakpoint - undefined
    at _pending.<computed> (node:internal/deps/node-inspect/lib/internal/inspect_client:243:27)
    at Client._handleChunk (node:internal/deps/node-inspect/lib/internal/inspect_client:213:11)
    at Socket.emit (node:events:327:20)
    at Socket.EventEmitter.emit (node:domain:486:12)
    at addChunk (node:internal/streams/readable:304:12)
    at readableAddChunk (node:internal/streams/readable:279:9)
    at Socket.Readable.push (node:internal/streams/readable:218:10)
    at TCP.onStreamRead (node:internal/stream_base_commons:192:23)
    at TCP.callbackTrampoline (node:internal/async_hooks:129:14) {
  code: -32000
}
debug> 

[aduh95]

@nodejs/inspector Is this a bug?

[benjamingr]

That's not a bug afaik debugging inside core isn't supported.

The user can use the userland readable-stream (slightly older though) and break there https://www.npmjs.com/package/readable-stream :]

[benjamingr]

(Or they can build core from source and put a literal debugger that worked for me in the past (and there is --inspect-brk-node but I don't think that'd help)

[github-actions[bot]]

It seems there has been no activity on this issue for a while, and it is being closed in 30 days. If you believe this issue should remain open, please leave a comment. If you need further assistance or have questions, you can also search for similar issues on Stack Overflow. Make sure to look at the README file for the most updated links.

[github-actions[bot]]

It seems there has been no activity on this issue for a while, and it is being closed. If you believe this issue should remain open, please leave a comment. If you need further assistance or have questions, you can also search for similar issues on Stack Overflow. Make sure to look at the README file for the most updated links.

[CyanChanges]

Trying to pass the --no-node-snapshot argument to node. It may resolves the issue.