Re: [boost] Nonlocking data structures.

From: Michael Dickey (mike_at_[hidden])
Date: 2008-04-17 19:47:03

Yes, I'm using a multi-core machine.   Where in my code would I need  
to add barriers, or is this perhaps a limitation in APR's CAS?

Thanks,
-Mike

On Apr 17, 2008, at 3:45 PM, Patrick Twohig wrote:
> Are you running it on a multicore machine or single core?  That  
> radically
> changes things.  I was having the same problem.  To test I ran 500  
> threads
> or so a third of them were producers.  My suspicion was that I wasn't
> enforcing the proper memory barriers because for x86 I had to write  
> my own
> CAS in assembly.
>
> On Thu, Apr 17, 2008 at 3:23 PM, Michael Dickey  
> <mike_at_[hidden]> wrote:
>
>> I wrote a C++ lock free queue implementation recently based on the
>> Michael & Scott algorithm, that uses APR's atomics.  It's available  
>> at:
>>
>>
>> http://svn.atomiclabs.com/pion-common/trunk/common/include/pion/PionLockFreeQueue.hpp
>>
>> You're welcome to use it but you should be aware that it's not quite
>> debugged yet.  It has issues when I tried using more than 1 producer
>> and 1 consumer thread.  I wasn't sure if this was a mistake I made in
>> the code, or a limitation of the algorithm, but I assume it's the
>> former.  Anyway, in the end I decided not to use the code for what I
>> was working on...  But if you can find and fix the bug, it's all
>> yours!  =)
>>
>> Of course, it depends on APR's atomics..  Boost does not have any
>> compare-and-swap abstraction as I far as I know, which seems to be a
>> basic requirement for any lock-free programming.  Or maybe it does  
>> and
>> I just don't know?
>>
>> Take care,
>> -Mike
>>
>>
>> On Apr 17, 2008, at 12:57 PM, Cory Nelson wrote:
>>> On Wed, Apr 16, 2008 at 9:58 PM, Patrick Twohig <p-twohig_at_[hidden]>
>>> wrote:
>>>> I've been looking through the docs and I was wondering if boost has
>>>> any
>>>> lock-free threadsafe containers.  I know it's been brought up on
>>>> the list
>>>> before, but I was curious if anybody had a working implementation.
>>>> If
>>>> somebody is working on them, I'd like to lend a hand if possible.
>>>
>>> I have some lock-free stack/queue code for x86/x64/ia64 in c++.  It
>>> only works with vc++ 2008 intrinsics right now, and the x64  
>>> version is
>>> dependant on the windows memory manager if used on older CPUs.  If
>>> people are interested in boostifying and porting it, I suppose we
>>> could do that.
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