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child_process: guard against race condition
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It is possible that the internal handleMessage() might try to send to
a channel that has been closed. The result can be an AssertionError.
Guard against this.

Fixes: #4205
PR-URL: #5153
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
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Trott authored and Myles Borins committed Feb 11, 2016
1 parent d421e85 commit fcc6479
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Showing 2 changed files with 37 additions and 0 deletions.
3 changes: 3 additions & 0 deletions lib/child_process.js
Original file line number Diff line number Diff line change
Expand Up @@ -313,6 +313,9 @@ function getSocketList(type, slave, key) {

var INTERNAL_PREFIX = 'NODE_';
function handleMessage(target, message, handle) {
if (!target._channel)
return;

var eventName = 'message';
if (!util.isNull(message) &&
util.isObject(message) &&
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34 changes: 34 additions & 0 deletions test/simple/test-cluster-disconnect-race.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,34 @@
'use strict';

// This code triggers an AssertionError on Linux in Node.js 5.3.0 and earlier.
// Ref: https://github.com/nodejs/node/issues/4205

var common = require('../common');
var assert = require('assert');
var net = require('net');
var cluster = require('cluster');
cluster.schedulingPolicy = cluster.SCHED_NONE;

if (cluster.isMaster) {
var worker1, worker2;

worker1 = cluster.fork();
worker1.on('message', common.mustCall(function() {
worker2 = cluster.fork();
worker1.disconnect();
worker2.on('online', common.mustCall(worker2.disconnect));
}, 2));

cluster.on('exit', function(worker, code) {
assert.strictEqual(code, 0, 'worker exited with error');
});

return;
}

var server = net.createServer();

server.listen(common.PORT, function retry() {
process.send('listening');
process.send('listening');
});

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