It sounds like you're talking about lazy source positions, but the code
you've listed there shouldn't be affected by that since it never symbolizes
a stack trace. You could confirm that by disabling it with the flag
--no-enable-lazy-source-positions.
If you added "var a = x.stack;" to your test8 function then it would
trigger symbolization (without printing it), since stack is actually a
function masquerading as a variable and so even accessing it will trigger
source position collection. I would then expect the first iteration to be
slower as it reparses, but then subsequent iterations would be fast.
Dan
On Mon, 10 Feb 2020 at 15:20, Wilfried Gösgens <dotheb...@gmail.com> wrote:
> Hi,
> reading the changelog I saw that many things changed about stacktrace
> generation in the recent V8 versions, which should change the performance
> of generating the error instance?
> I've tried this simple test with arangodb's arangosh and its embedded V8
> versions 7.1 and 7.9:
>
> function test1() {
> function test2() {
> function test3() {
> function test4() {
> function test5() {
> function test6() {
> function test7() {
> function test8() {
> x= new Error;
> return 1;
> }
> return test8();
> }
> return test7();
> }
> return test6();
> }
> return test5();
> }
> return test4();
> }
> return test3();
> }
> return test2();
> }
>
> before = time();
> for (let i = 1; i < 50; i ++) {
> test1();
> }
> print(time() - before);
>
>
> 7.1: - (as in ArangoDB 3.6) 0.0012750625610351562
> 7.9: - (as in current devel) 0.6016845703125
>
> The figures are similar when I throw the error and catch it inside that
> for loop.
> I've read that later V8 reparses the source in order to get the printeable
> stacktrace; is this what gives such a worse performance here?
> If yes, which way is one to achieve similar / faster performance with
> recent V8 versions?
>
> Cheers,
> Willi
>
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