Re: [boost] boost lockfree queue.hpp - alternate implementation w/o compare_exchange

Subject: Re: [boost] boost lockfree queue.hpp - alternate implementation w/o compare_exchange
From: Giovanni Piero Deretta (gpderetta_at_[hidden])
Date: 2015-10-22 04:18:55

On 22 Oct 2015 9:04 a.m., "Gavin Lambert" <gavinl_at_[hidden]> wrote:
>
> On 22/10/2015 20:57, Giovanni Piero Deretta wrote:
>>
>> It seems to me then it is not really lock free then, right?
>
>
> There's a difference between "lock free" and "wait free" (though I
haven't examined the code to see which most correctly applies here).
>
> Wait-free is better than lock-free, of course, but it's also incredibly
hard to achieve in an MPMC problem.
>
>

Lock free still requires at least one thread to make progress in any
situation. If this were the case  yield wouldn't be necessary. As I t is I
do not think it qualifies even as obstruction-free.