Try/Catch performance overhead

JavaScript performance comparison

Revision 14 of this test case created

Info

Using try/catch inside of functions that allocate lots of variables introduces significant overhead. See this discussion related to node.js https://groups.google.com/forum/#!topic/nodejs-dev/E-Re9KDDo5w

Interestingly, other js engines don't have this overhead. All test runs have pretty uniform performance. But they are also significantly slower than the v8 control case.

Preparation code

<script>
  var tries = 10000;

  function _test1(tries) {
   var s = [];
   for (var i = 0; i < tries; i++) s.push(i);
   return s;
  }
 
  function _test2(tries) {
   var s = [];
   try {
    for (var i = 0; i < tries; i++) s.push(i);
    throw new Error();
   }
   catch (ex) {}
   return s;
  }

  function _test3(s, tries) {
   for (var i = 0; i < tries; i++) s.push(i);
   throw new Error();
  }

  function test1() {
   var s = _test1(tries);
   
   return s;
  }
 
  function test2() {
   var s = _test2(tries);
   
   return s;
  }
 
  function test3() {
   var s = [];

   try {
    _test3(s, tries);
   }
   catch (ex) {}
   
   return s;
  }
</script>

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
control - no try/catch
test1();
pending…
try/catch inside function
test2();
pending…
try/catch outside function
test3();
pending…

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Revisions

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