[D-runtime] gc_atomic

[Fawzi Mohamed]

On 23-lug-10, at 04:48, Sean Kelly wrote:

> I had a conversation with an OS guy at Apple a while back about how  
> to do collections correctly on OSX.  In short, Semaphores aren't the  
> way to do it.  druntime uses the Mach API instead, and it works a  
> lot like collections on Windows.

yes I also had used the mach api (that is what I am replacing with  
atomic ops), but still had (very seldomly) problems. But if you don't  
see them, then maybe I did something wrong/diffrently.

>
> On Jul 22, 2010, at 7:18 PM, Fawzi Mohamed wrote:
>
>> Well on the end I did manage to get useful debug info most of the  
>> time compiling everything with debug symbols.
>> But sometime when being at such a low level everything might go  
>> wrong, even printf might fail because it isn't signal safe... write  
>> would be signal safe, but is a bit a pain to use, but to print just  
>> fixed string it might be a better option...
>>
>> then there is the thing that osx has the bad habit of keeping  
>> "full" locks and other allocation stuff in pools protected by  
>> spinlocks in the kernel, and it is possible to suspend a thread  
>> with the spinlock taken.
>>
>> That is why I switched to atomic instead of semaphores.
>>
>> About allocations I moved the allocations of getAll outside the  
>> lock, because starting a GC collection to satisfy that allocation  
>> could give problems.
>>
>> Don't know if any of this might help you with your bug.
>>
>> Happy debugging
>>
>> Fawzi
>> On 23-lug-10, at 03:36, Sean Kelly wrote:
>>
>>> Thanks!  Frankly, the greatest obstacle I have for debugging right  
>>> now is that debug symbol generation is broken on OSX.  I can get  
>>> the function that failed at best (sometimes just a stack of "????"  
>>> symbols).  I've always done a lot of printf debugging with D, but  
>>> for low-level issues like this, it doesn't really do the trick.
>>>
>>> On Jul 22, 2010, at 6:16 PM, Fawzi Mohamed wrote:
>>>
>>>> you might be interested to this set of changes I did to tango to  
>>>> get rid of some low probability bugs, and to make my debugging of  
>>>> blip easier:
>>>>
>>>> see
>>>> http://www.dsource.org/projects/tango/ticket/1959
>>>>
>>>> ciao
>>>> Fawzi
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