Le 20/12/2013 17:07, Nicolas B. Pierron a écrit :
On 12/20/2013 06:24 AM, Julien Wajsberg wrote:
So here is my wishlist (please cope with any inacuraccies I could make):
* have diagnostics about what happens within the JS engine:
+ when and why objects are handled as Hashmap instead of Structs (why
=== which JS code is producing this)
If you are talking about objects, this is only function of the number
of properties on the object.
I thought doing a "delete" could move the object shape to a hashmap?
IIRC a couple of months ago, the devtools team (Joe Walker
specifically?) made some changes to the devtools code to change some
"delete" to "= undefined" and that improved performance.
(I do not remember what is the limit, as it changed recently for the
GameBoy benchmark)
The last number I remember is 128 (which sounded like a lot), but it may
be outdated.
I think that what Julien is asking doesn't have to do only with the
current heuristics. As you suggest, the heuristics can change over time
and it's certainly a lot of work for non-SM devs to track what object
has a Shape and which is a HashMap. It may be good to know what objects
are HashMaps (regardless of this heuristics at first) to investigate
whether it is caused by the source code or a change in SM heuristics for
instance.
+ (you can see I did some Java in the past ;) )
I am sorry, we cannot do anything for you about that.
Mouahahahah :-)
+ show when a GC happens, show also why this happens if possible and
if it makes sense
A GC happens because we have reached a limit of allocation or because
we have receive a srinking GC notification from the system. So I
guess you want to see what might cause a GC to be triggered? In which
case I can easily answer everything which has a "[", a "{" or a "new".
I imagine function expression, generator expressions, RegExp literals,
JSON.parse, etc. count too?
In any case, this is really a good info.
David
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