Skip to content
Permalink
Browse files

child_process: fix data loss with readable event

This commit prevents child process stdio streams from being
automatically flushed on child process exit/close if a 'readable'
event handler has been attached at the time of exit.

Without this, child process stdio data can be lost if the process
exits quickly and a `read()` (e.g. from a 'readable' handler)
hasn't had the chance to get called yet.

Fixes: #5034
PR-URL: #5036
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
  • Loading branch information...
mscdex authored and MylesBorins committed Feb 2, 2016
1 parent 66d1115 commit 29951cf36a99f4f3811f231ce29fe837661cb41f
Showing with 16 additions and 4 deletions.
  1. +1 −1 lib/internal/child_process.js
  2. +15 −3 test/parallel/test-child-process-flush-stdio.js
@@ -217,7 +217,7 @@ util.inherits(ChildProcess, EventEmitter);
function flushStdio(subprocess) {
if (subprocess.stdio == null) return;
subprocess.stdio.forEach(function(stream, fd, stdio) {
if (!stream || !stream.readable)
if (!stream || !stream.readable || stream._readableState.readableListening)
return;
stream.resume();
});
@@ -8,10 +8,22 @@ const p = cp.spawn('echo');
p.on('close', common.mustCall(function(code, signal) {
assert.strictEqual(code, 0);
assert.strictEqual(signal, null);
spawnWithReadable();
}));

p.stdout.read();

setTimeout(function() {
p.kill();
}, 100);
function spawnWithReadable() {
const buffer = [];
const p = cp.spawn('echo', ['123']);
p.on('close', common.mustCall(function(code, signal) {
assert.strictEqual(code, 0);
assert.strictEqual(signal, null);
assert.strictEqual(Buffer.concat(buffer).toString().trim(), '123');
}));
p.stdout.on('readable', function() {
let buf;
while (buf = this.read())
buffer.push(buf);
});
}

0 comments on commit 29951cf

Please sign in to comment.
You can’t perform that action at this time.