Watch recursion

So recently I got problems in webpack, where the watcher is spamming “compile” events for files that are updated before watching starts. The rabbit hole was deep, but led me to watchpack.

So:

1. So at some point doInitialScan is processed in DirectoryWatcher.
2. This, at least for files, runs setFileTime
3. As the inital flag is set, this this.files[filePath] = [initial ? Math.min(now, mtime) : now, mtime]; mostly equals to this.files[filePath] = [mtime, mtime];, because the file mtime will be smaller the time now (in case I edited file before running watcher).
4. Next at some point it gets to process.nextTick and var ts = data[0] === data[1] ? data[0] + FS_ACCURACY : data[0]; and if(ts >= startTime)watcher.emit("change", data[1]);
5. As this data[0] === data[1] is true (check point 3), FS_ACCURACY is added. So ts is bigger than startTime (delivered from webpack compiler it’s self.startTime = Date.now();).
6. So for aprox 10 seconds (FS_ACCURACY = 10000 milis) it’ss spamming compile events, until the date now reaches file mtime+10 secs.

This doesn’t feel right 😕

[YurySolovyov]

Adjusting concurrency seems like a crutch, race condition like that should never happen by design.

If that means things will go slower, it is fine, cause spamming like that confusing and slowing developers anyway.

Please, dear core team, do not trade speed for correctness and robustness.

[alexander-akait]

@trsh duplicate https://github.com/webpack/watchpack/issues/53?