Stopping a node.js program with SIGINT while esbuild watch is running sometimes causes EPIPE error

[AlCalzone]

I have a Node.js program that uses esbuild's watch mode to compile React TSX files. In this program, i listen for the SIGINT signal to shut down the watch process gracefully:

	const buildProcess = await build({
	    // These are the remaining build options
		...getReactBuildOptions(entryPoints, tsConfigPath),

		watch: true,
	});

	process.on("SIGINT", () => {
		console.log();
		console.log("SIGINT received, shutting down...");
		buildProcess.stop?.();
	});

However most of the time, I'm getting this error instead:

node:events:368
      throw er; // Unhandled 'error' event
      ^

Error: write EPIPE
    at afterWriteDispatched (node:internal/stream_base_commons:164:15)
    at writeGeneric (node:internal/stream_base_commons:155:3)
    at Socket._writeGeneric (node:net:780:11)
    at Socket._write (node:net:792:8)
    at writeOrBuffer (node:internal/streams/writable:389:12)
    at _write (node:internal/streams/writable:330:10)
    at Socket.Writable.write (node:internal/streams/writable:334:10)
    at Object.writeToStdin (C:\Repositories\adapter-dev\node_modules\esbuild\lib\main.js:2027:19)
    at sendRequest (C:\Repositories\adapter-dev\node_modules\esbuild\lib\main.js:672:14)
    at Object.stop (C:\Repositories\adapter-dev\node_modules\esbuild\lib\main.js:1289:15)
Emitted 'error' event on Socket instance at:
    at emitErrorNT (node:internal/streams/destroy:157:8)
    at emitErrorCloseNT (node:internal/streams/destroy:122:3)
    at processTicksAndRejections (node:internal/process/task_queues:83:21) {
  errno: -4047,
  code: 'EPIPE',
  syscall: 'write'
}

It seems that the child process that esbuild starts, gets killed by the SIGINT before stop gets called.

[evanw]

I figured out how to reproduce this. This doesn't even require watch mode to be enabled. You can reproduce this with a simple plugin that just builds infinitely:

process.on("SIGINT", () => console.log('SIGINT'))
esbuild.build({
  stdin: { contents: `import 'x'` },
  bundle: true,
  plugins: [{
    name: 'infinity',
    setup(build) {
      build.onResolve({ filter: /.*/ }, args => ({ path: args.path, namespace: 'x' }))
      build.onLoad({ filter: /.*/ }, args => ({
        contents: `
          import 'a${args.path}'
          import 'b${args.path}'
        `,
      }))
    },
  }],
}).catch(e => console.error('caught ' + e))

It looks like maybe this happens because I'm not passing a callback to the stdin.write function.

[nemphys]

@evanw I am facing the same issue, but on a web service that serves scripts minified by esbuild.

Since I already have a graceful shutdown procedure in place, which kindly waits for the various components of the application to shut down taking their time, I am wondering if we could have some way of letting esbuild do its thing, (conditionally) ignoring the SIGINT signal.

Right now (though this commit is an improvement), all we get is a failed build.

[evanw]

The issue you are commenting on was closed because it has been fixed. If you want the fix, please update your version of esbuild to one that has the fix. Or, if your issue is different than this one, please file a new issue and include a way to demonstrate your problem so it can be fixed too.

[evanw]

Sorry, I just re-read the last sentence. I think you're asking for esbuild to not fail the build if the data from its child process is cut off? That doesn't sound like a good idea to me since it could mask all kinds of legitimate issues. Why not just ignore build failures from esbuild if your graceful shutdown procedure is in progress?

[nemphys]

Yes, that is what I am currently doing.

I used the word "conditionally", since maybe we could have some special handler (eg through some kind of init option) that could signify this specific case.

But now that I think about it, the child process should ignore the SIGINT signal (so that it does not stop doing its job), which I suppose is not possible, right?