Skip to content
This repository

Timers can false start 1ms earlier than needed #4194

Closed
wants to merge 1 commit into from

4 participants

Alexey Kupershtokh Ben Noordhuis Nodejs Jenkins Isaac Z. Schlueter
Alexey Kupershtokh

( Related issue: #534 )

@bnoordhuis , you actually introduced another bug in 82e9da9

Lets say:

var _idleStart = 0;
var msecs = 1000;
var now = 999;
var diff = now - _idleStart;
console.log('diff', diff);
if (diff + 1 < msecs) {
  console.log('schedule for', msecs - diff, 'ms more');
} else {
  console.log('immediate exec');
}

Outputs

diff 999
immediate exec

which is definitely wrong.

There is a complete test for this bug. You can include into node/test/simple:

var common = require('../common');
var assert = require('assert');
var i;

var N = 30;

var last_i = 0;
var last_ts = 0;
var start = Date.now();

var f = function(i) {
  if (i <= N) {
    // check order
    assert(i == last_i + 1, 'iteration order is broken on ' + i + 'th iteration, prev is ' + last_i);
    last_i = i;

    // check that this iteration has been fired at leat 1ms later than the previous
    var now = Date.now();
    console.log(i, now);
    assert(now >= last_ts + 1, 'iteration has been fired within the same ms as the previous on ' + i + 'th iteration');
    last_ts = now;

    // schedule next iteration
    setTimeout(f, 1, i + 1);
  }
}
f(1);

it fails on the current master:

1 1351075317097
2 1351075317103
3 1351075317106
4 1351075317106

timers.js:102
            if (!process.listeners('uncaughtException').length) throw e;
                                                                      ^
AssertionError: iteration has been fired within the same ms as the previous on 4th iteration
    at f (/home/wicked/Alawar/node/test/simple/test-next-tick-ordering3.js:41:5)
    at exports.setTimeout.timer._onTimeout (timers.js:195:16)
    at Timer.list.ontimeout (timers.js:100:19)
    at process.startup.processMakeCallback.process._makeCallback (node.js:248:20)

If I revert the 82e9da9 , the test passes.

Ben Noordhuis

@bnoordhuis , you actually introduced another bug in joyent/node@82e9da9

You'll note that I'm not @ry. I'm a lot taller and more handsome to boot.

Can you send a PR for this? Reverting 82e9da9 seems reasonable enough and a quick test indicates that it works.

Nodejs Jenkins
Collaborator

Can one of the admins verify this patch?

Isaac Z. Schlueter
Collaborator

Landed on 9fae4dc (rebased to current v0.10 code).

Thanks!

Isaac Z. Schlueter isaacs closed this
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
This page is out of date. Refresh to see the latest.

Showing 2 changed files with 49 additions and 1 deletion. Show diff stats Hide diff stats

  1. +1 1  lib/timers.js
  2. +48 0 test/simple/test-timers-ordering.js
2  lib/timers.js
@@ -76,7 +76,7 @@ function insert(item, msecs) {
76 76 var first;
77 77 while (first = L.peek(list)) {
78 78 var diff = now - first._idleStart;
79   - if (diff + 1 < msecs) {
  79 + if (diff < msecs) {
80 80 list.start(msecs - diff, 0);
81 81 debug(msecs + ' list wait because diff is ' + diff);
82 82 return;
48 test/simple/test-timers-ordering.js
... ... @@ -0,0 +1,48 @@
  1 +// Copyright Joyent, Inc. and other Node contributors.
  2 +//
  3 +// Permission is hereby granted, free of charge, to any person obtaining a
  4 +// copy of this software and associated documentation files (the
  5 +// "Software"), to deal in the Software without restriction, including
  6 +// without limitation the rights to use, copy, modify, merge, publish,
  7 +// distribute, sublicense, and/or sell copies of the Software, and to permit
  8 +// persons to whom the Software is furnished to do so, subject to the
  9 +// following conditions:
  10 +//
  11 +// The above copyright notice and this permission notice shall be included
  12 +// in all copies or substantial portions of the Software.
  13 +//
  14 +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  15 +// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  16 +// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  17 +// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  18 +// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  19 +// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  20 +// USE OR OTHER DEALINGS IN THE SOFTWARE.
  21 +
  22 +var common = require('../common');
  23 +var assert = require('assert');
  24 +var i;
  25 +
  26 +var N = 30;
  27 +
  28 +var last_i = 0;
  29 +var last_ts = 0;
  30 +var start = Date.now();
  31 +
  32 +var f = function(i) {
  33 + if (i <= N) {
  34 + // check order
  35 + assert.equal(i, last_i + 1, 'order is broken: ' + i + ' != ' + last_i + ' + 1');
  36 + last_i = i;
  37 +
  38 + // check that this iteration is fired at least 1ms later than the previous
  39 + var now = Date.now();
  40 + console.log(i, now);
  41 + assert(now >= last_ts + 1, 'current ts ' + now + ' < prev ts ' + last_ts + ' + 1');
  42 + last_ts = now;
  43 +
  44 + // schedule next iteration
  45 + setTimeout(f, 1, i + 1);
  46 + }
  47 +};
  48 +f(1);

Tip: You can add notes to lines in a file. Hover to the left of a line to make a note

Something went wrong with that request. Please try again.