net.listen does not emit 'listening' event when in --eval mode

[rmg]

Failing unit test submitted as PR #1581

I found this when trying to confirm the format of the address object. The following hangs on most releases of node higher than 0.10.38:

node -e "require('net').createServer().listen(0, function() { console.log(this.address()); this.close(); });"

It seems that Server does not emit a listen event when no address is specified and is called in eval mode.

I don't fully understand how the regression was introduced, but git bisect seemed pretty confident that it was in 5b636fe.

/to @trevnorris for the indicated commit
/cc @piscisaureus @sam-github @brendanashworth

[trevnorris]

wtf. That commit was 2 years ago?

Assigning this to myself.

[rmg]

@trevnorris agreed, seriously wtf. Looking forward to the fix, 'cause I have no idea..

[trevnorris]

Just to clarify, it doesn't matter what port number is passed.

[trevnorris]

The call to emitListeningNT isn't getting called in lib/net.js. Unfortunately none of the code linked in the bisect event exists anymore, so the issue must have just propagated strangely.

UPDATE: _tickCallback() is never reached, so nothing in the nextTickQueue is run. Figuring out why.

UPDATE: Seems that evalScript() from src/node.js simply runs the script in vm.runInThisContext(). Which doesn't cause the nextTickQueue to be processed for some reason.

UPDATE: Reason the nextTickQueue isn't processed is because the call to .listen() is actually synchronous. Check the call stack:

    at Server._listen2 (net.js:1210:22)
    at listen (net.js:1228:10)
    at Server.listen (net.js:1318:5)
    at [eval]:1:31
    at Object.exports.runInThisContext (vm.js:54:17)
    at Object.<anonymous> ([eval]-wrapper:6:22)
    at Module._compile (module.js:431:26)
    at evalScript (node.js:567:25)
    at startup (node.js:95:9)
    at node.js:959:3

I'm open to ideas of the best way to get the call stack to flip over.

[trevnorris]

@rmg So I've determined, mostly, why it's happening, but I'm not sure of the best fix. Thoughts?

[brendanashworth]

Cross linking to nodejs/node-v0.x-archive#14168.

[bnoordhuis]

There's an easy "fix" (maybe "hack" is more appropriate): defer evaluation for a tick.

diff --git a/src/node.js b/src/node.js
index cb50341..3a7e3c9 100644
--- a/src/node.js
+++ b/src/node.js
@@ -558,8 +558,10 @@
              'return require("vm").runInThisContext(' +
              JSON.stringify(body) + ', { filename: ' +
              JSON.stringify(name) + ' });\n';
-    var result = module._compile(script, name + '-wrapper');
-    if (process._print_eval) console.log(result);
+    process.nextTick(function() {
+      var result = module._compile(script, name + '-wrapper');
+      if (process._print_eval) console.log(result);
+    });
   }

   function createWritableStdioStream(fd) {

[trevnorris]

@bnoordhuis Nice. Want to handle the PR for that, or want me to?

[bnoordhuis]

I'll file a PR, I don't think I've had a commit in for a while now. :-)

[brendanashworth]

Fix: #1793

[bnoordhuis]

Fixed by 93a44d5.