We suspected that, but tested it anyway :)

On Friday, February 14, 2020 at 9:54:28 AM UTC-5, Santiago Aboy Solanes 
wrote:
>
> Adding to that, this configuration
>   Pointer Compression ON, 31-bit Smis OFF -> Memory leak
> is the same as
>   Pointer Compression ON, 31-bit Smis ON -> Memory leak
> since Pointer Compression forces 31 bit smis 
> <https://cs.chromium.org/chromium/src/v8/BUILD.gn?l=377&rcl=142ac8d31d94082d90a1d2983db88f5730748185>
>  on 
> 64 bit archs
>
> On Fri, Feb 14, 2020 at 2:46 PM Leszek Swirski <[email protected] 
> <javascript:>> wrote:
>
>> That sounds like a build config mismatch, or something similar -- 31-bit 
>> Smis shouldn't cause major breakage, but will if e.g. one header has the 
>> build flag enabled and another doesn't.
>>
>> On Fri, Feb 14, 2020 at 3:43 PM <[email protected] <javascript:>> 
>> wrote:
>>
>>> Sorry, here's a clarification. This is what we're seeing with 8.0:
>>>
>>> Pointer Compression ON, 31-bit Smis ON -> Memory leak
>>> Pointer Compression ON, 31-bit Smis OFF -> Memory leak
>>> Pointer Compression OFF, 31-bit Smis ON -> Major breakage
>>> Pointer Compression OFF, 31-bit Smis OFF -> All good
>>>
>>> On Friday, February 14, 2020 at 9:33:10 AM UTC-5, Santiago Aboy Solanes 
>>> wrote:
>>>>
>>>> Do you mean that v8_enable_pointer_compression = *false* and 
>>>> v8_enable_31bit_smis_on_64bit_arch = *true* "yielded a V8 build that 
>>>> broke a majority of our test suite, including this memory leak test"?
>>>> If that's the case, this is not a pointer compression failure.
>>>>
>>>> Pointer Compression needs 31 bit smis, but 31 bit smis doesn't need 
>>>> Pointer Compression.
>>>>
>>>> On Fri, Feb 14, 2020 at 2:29 PM <[email protected]> wrote:
>>>>
>>>>> That particular combination yielded a V8 build that broke a majority 
>>>>> of our test suite, including this memory leak test.
>>>>>
>>>>> We didn't spend much time investigating, but the build utterly broke 
>>>>> interception (e.g., bad data in FunctionCallbackInfo), so we abandoned it.
>>>>>
>>>>> On Friday, February 14, 2020 at 5:13:35 AM UTC-5, Santiago Aboy 
>>>>> Solanes wrote:
>>>>>>
>>>>>> Quick question: Have you tried with v8_enable_pointer_compression = 
>>>>>> false and v8_enable_31bit_smis_on_64bit_arch = true?
>>>>>>
>>>>>> On Fri, Feb 14, 2020 at 7:54 AM Yang Guo <[email protected]> wrote:
>>>>>>
>>>>>>> +Ulan Degenbaev +Igor Sheludko 
>>>>>>>
>>>>>>> On Thu, Feb 13, 2020 at 8:36 PM <[email protected]> wrote:
>>>>>>>
>>>>>>>> Greetings!
>>>>>>>>
>>>>>>>> Our project is a V8 embedding library for .NET on Windows. We have 
>>>>>>>> a test that spins up a context, runs SunSpider, and destroys the 
>>>>>>>> isolate. 
>>>>>>>> We run it in a loop to check for memory leaks.
>>>>>>>>
>>>>>>>> This test showed a dramatic leak with V8 8.0 that wasn't there with 
>>>>>>>> 7.9. Our tools found nothing suspicious in the managed and native 
>>>>>>>> heaps, 
>>>>>>>> but the process's private memory size kept increasing.
>>>>>>>>
>>>>>>>> Based on some quick research and a little guesswork, we rebuilt 
>>>>>>>> with v8_enable_pointer_compression and 
>>>>>>>> v8_enable_31bit_smis_on_64bit_arch 
>>>>>>>> both set to false. To our surprise this completely eliminated the leak!
>>>>>>>>
>>>>>>>> We'd like to report this issue to the V8 team, but we have no 
>>>>>>>> simple native repro code. Can someone suggest a way to gather some 
>>>>>>>> useful 
>>>>>>>> diagnostics?
>>>>>>>>
>>>>>>>> Thanks!
>>>>>>>>
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>

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