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process: optimize process.nextTick()
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33% performance boost on large nextTick queues.
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@bnoordhuis
bnoordhuis committed Oct 31, 2011
1 parent 5fee1ff commit 4d4900f
Showing 1 changed file with 5 additions and 7 deletions.
12 changes: 5 additions & 7 deletions src/node.js
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Expand Up @@ -185,20 +185,18 @@
var l = nextTickQueue.length;
if (l === 0) return;

var q = nextTickQueue;
nextTickQueue = [];

try {
for (var i = 0; i < l; i++) {
nextTickQueue[i]();
}
for (var i = 0; i < l; i++) q[i]();
}
catch (e) {
nextTickQueue.splice(0, i + 1);
if (i + 1 < l) {
if (nextTickQueue.length) {
process._needTickCallback();
}
throw e; // process.nextTick error, or 'error' event on first tick
}

nextTickQueue.splice(0, l);
};

process.nextTick = function(callback) {
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2 comments on commit 4d4900f

@koichik
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@koichik koichik commented on 4d4900f Nov 1, 2011

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@bnoordhuis - If a callback throws an exception, the following callbacks of q are never called (testcase is here).
The remaining callbacks must be concatenated before nextTickQueue.

       catch (e) {
+        if (i + 1 < l) {
+          nextTickQueue = q.slice(i + 1).concat(nextTickQueue);
+        }
         if (nextTickQueue.length) {

@bnoordhuis
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I'll take @koichik's patch. This commit is phase 1 of a two-pronged attack on getting rid of the O(n) calls to process._needTickCallback() because that's the real performance drain. Dropping the Array.splice() is just icing on the cake.

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