Dang, I was kind-of hoping for the long version :). I would assume it
wouldn't actually be any more memory intensive, but rather then it comes
down to speed? So I did a quick test. If you are interested in the full
source, I can provide it, however for simplicity I will just provide
snippets. I made two functions:
Local<String> NewLocalString(Isolate* isolate) {
EscapableHandleScope handle_scope(isolate);
Local<String> specifier = String::NewFromUtf8(isolate, "foobar");
return handle_scope.Escape(specifier);
}
Persistent<String> *NewPersistentString(Isolate *isolate) {
HandleScope handle_scope(isolate);
Local<String> specifier = String::NewFromUtf8(isolate, "foobar");
return new Persistent<String>(isolate, specifier);
}
Both just create a string, but one uses a Local and the other uses a
Persistent. Then I simulate using them both a million times:
{
HandleScope handle_scope(isolate);
for(int i = 0; i < 1000 * 1000; i ++ ) {
Local<String> str = NewLocalString(isolate);
}
}
{
for(int i = 0; i < 1000 * 1000; i ++ ) {
Persistent<String> *str = NewPersistentString(isolate);
str->Reset();
delete str;
}
}
Wrapping each in a std::chrono::high_resolution_clock::now(); produced
interesting results. Here are my first 5 runs of the compiled binary that
tries to benchmark both each run:
./speed_check
Elapsed Local: 100991684ns
Elapsed Persistent: 102445417ns
./speed_check
Elapsed Local: 95274546ns
Elapsed Persistent: 103189948ns
./speed_check
Elapsed Local: 116059276ns
Elapsed Persistent: 103059742ns
./speed_check
Elapsed Local: 118289635ns
Elapsed Persistent: 102510472ns
./speed_check
Elapsed Local: 116038521ns
Elapsed Persistent: 103183176ns
This is just one crude isolated test case on one hardware profile, but the
fluctuating results are interesting.
On Tuesday, 10 September 2019 16:03:15 UTC-4, Ben Noordhuis wrote:
>
> On Tue, Sep 10, 2019 at 9:10 PM Joel Scarfone <[email protected]
> <javascript:>> wrote:
> >
> > What is the difference between using an `EscapableHandleScope` to
> propagate a `Value` and just creating a `Persistent` from the local I
> intent to return from a function? Is one more performant than the other, or
> is it just usability?
> >
> > Joel
>
> EscapableHandleScope is faster. Persistent handles create more work
> for the garbage collector.
>
> (That's the pithy version of a longer response I wrote and then
> scrapped because of too much details.)
>
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