Syntax error in a file crashes babel-watch

[steelbrain]

Not only it crashes but also triggers a bug in Node.js making it gets stuck at 100% cpu usage.

I get infinite of this in dtrace of the process with 100% cpu usage

dtrace: error on enabled probe ID 2134 (ID 318: syscall::read:return): invalid kernel access in action #12 at DIF offset 92

I also get this in my log

Error: Cannot find module 'our-storage'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/Users/steel/w/d/triangle/packages/container/lib/projects.js:3:1)
    at Module._compile (module.js:570:32)
    at babelWatchLoader (/Users/steel/w/d/triangle/node_modules/babel-watch/runner.js:50:13)
    at Object.require.extensions.(anonymous function) [as .js] (/Users/steel/w/d/triangle/node_modules/babel-watch/runner.js:61:7)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
fs.js:786
    return binding.writeBuffer(fd, buffer, offset, length, position);
                   ^

Error: EPIPE: broken pipe, write
    at Error (native)
    at Object.fs.writeSync (fs.js:786:20)
    at handleFileLoad (/Users/steel/w/d/triangle/node_modules/babel-watch/babel-watch.js:273:27)
    at handleFileLoad (/Users/steel/w/d/triangle/node_modules/babel-watch/babel-watch.js:170:7)
    at ChildProcess.app.on (/Users/steel/w/d/triangle/node_modules/babel-watch/babel-watch.js:263:5)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:191:7)
    at process.nextTick (internal/child_process.js:744:12)
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)

I'm on macOS Sierra, with Node v6.9.1 and babel-watch v2.0.3

[kmagiera]

Thanks @steelbrain for reporting and sorry for not getting back to you earlier.

Would you be able to provide a more specific repro scenario as I couldn't reproduce the issue only based on what you've provided. Here is what I tried:

1. Create simple project with app.js file with the following content:

console.log("Hello");

2. Run babel-watch app.js
3. See it runs correctly (prints Hello)
4. Update app.js and remove last quotation mark to introduce a syntax error
5. Get the following error printed:

Babel compilation error SyntaxError: /private/tmp/kaka/app.js: Unterminated string constant (1:12)
> 1 | console.log("Hello)

5. Update app.js again to get rid of the syntax error
6. See babel-watch restart again and runs the app correctly

[steelbrain]

Hi @kmagiera

I cannot provide any solid info any time soon but to tell you what fixed the issue for me, I basically wrapped all the fs.*Sync calls with a try { fs.*Sync(...) } catch (_) { process.exit() }

It not only fixed the error for me, but also fixed the scenarios where a babel-watch spawned process will be backgrounded and will take 100% cpu printing only the syscall read kernel error I posted in my first post. I hope this gives you an idea of what the problem might be, my random guess was that the spawned child process was writing to an fd created by the parent and when the parent process crashes it causes a deadlock for the child.

[kmagiera]

@steelbrain thanks anyways. I think that your issue might have been resolved by #38 merged earlier today which basically catches and ignores "EPIPE". That error could've been thrown when child process have died (perhaps due to syntax error) and make parent process hang in trying to write to the pipe. Would you be able to try the newest version and see if you're still having this problem? If so feel free to reopen the issue