Interesting, nice catch!

2017-03-12 20:44 GMT+02:00 Brion Vibber <[email protected]>:

> Ok, they've confirmed it's a bug in the JS engine -- larger
> SharedArrayBuffer objects had a different signature, breaking the checks,
> while short buffers still passed in whatever automatic tests they might
> have had.
>
> Should get fixed somewhere down the line. :)
>
> -- brion
>
> On Mar 10, 2017 1:06 PM, "Brion Vibber" <[email protected]> wrote:
>
>> On Mar 10, 2017 5:51 AM, "Jukka Jylänki" <[email protected]> wrote:
>>
>> Haven't tried out Edge at all with asm.js SharedArrayBuffer yet. I wonder
>> if it fails in smaller test cases already of this pattern?
>>
>>
>> Testing more carefully... Yes it fails right out in a simple test case,
>> might be a regression or maybe it never worked. :)
>>
>> I've reported upstream; supposedly the right place for JS engine issues
>> is straight to the ChakraCore github: https://github.com/Mic
>> rosoft/ChakraCore/issues/2672
>>
>> -- brion
>>
>>
>> 2017-03-10 5:37 GMT+02:00 Brion Vibber <[email protected]>:
>>
>>> Whoops, forgot my sample URL to reproduce:
>>>
>>> https://brionv.com/misc/ogv.js/demo-mt/#file=Knowledge_for_E
>>> veryone_(short_cut).webm&player=js-mt&size=480p.vp9.webm&sou
>>> rce=shortlist-vp9
>>>
>>> (Only the VP9 decoder has the multithread mode and I'm seeing good
>>> results, though it currently blocks the main thread during decoding I can
>>> easily fix that. And it's a little... hang-y sometimes, possibly due to not
>>> waiting on thread creation if the thread pool fills up.)
>>>
>>> -- brion
>>>
>>> On Thu, Mar 9, 2017 at 7:29 PM, Brion Vibber <[email protected]> wrote:
>>>
>>>> Is Edge known to be working (or broken) with emscripten's pthreads mode?
>>>>
>>>> I've got libvpx running multithreaded in ogv.js on Safari Tech Preview
>>>> and Firefox Dev Edition, but am having some trouble with Edge in the
>>>> current Windows Insider build (15048). (Have to enable 'Experimental JS
>>>> features' in about:flags to get Atomics and SharedArrayBuffer.)
>>>>
>>>> It's throwing an error "SCRIPT5664: The operation is not supported on
>>>> this typed array type" in the initMainThreadBlock function from
>>>> library_pthread.js, on this line:
>>>>
>>>>       Atomics.store(HEAPU32, (PThread.mainThreadBlock + {{{
>>>> C_STRUCTS.pthread.tsd }}} ) >> 2, tlsMemory); // Init thread-local-storage
>>>> memory array.
>>>>
>>>> As far as I can tell it should be working; HEAPU32 is a Uint32Array,
>>>> its buffer is a SharedArrayBuffer instance, and the memory locations seem
>>>> in line with what's expected.
>>>>
>>>> The Atomics implementation in Edge's JS engine is at
>>>> https://github.com/Microsoft/ChakraCore/blob/master/lib/Runt
>>>> ime/Library/AtomicsObject.cpp and I don't see anything obviously
>>>> surprising in the source, though it could conceivably be out of sync. Nor
>>>> do I encounter the error if I just instantiate a SharedArrayBuffer and a
>>>> Uint32Array and call Atomics.store on it.
>>>>
>>>> It's possible I've broken something in my modularization fixes that
>>>> doesn't break in the other browsers...
>>>>
>>>> Thanks!
>>>>
>>>> -- brion
>>>>
>>>
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