Re: [boost] Boost.Fiber mini-review September 4-13

Subject: Re: [boost] Boost.Fiber mini-review September 4-13
From: Agustín K-ballo Bergé (kaballo86_at_[hidden])
Date: 2015-09-05 09:12:51

On 9/5/2015 3:42 AM, Oliver Kowalke wrote:
> 2015-09-04 21:05 GMT+02:00 Agustín K-ballo Bergé <kaballo86_at_[hidden]>:
>
>> Although holding a mutex while firing on the condition variable is
>> considered bad practice, so this would be even better:
>>
>
> do you have a reference?

Well, it's not exactly new and it is baked into the design of 
`std::condition_variable`. I guess this will have to do for reference: 
http://en.cppreference.com/w/cpp/thread/condition_variable/notify_one

> in Butenhof's examples pthread_cond_signal/pthread_cond_broadcast are
> always called if front of pthread_mutex_unlock

Alas pthread specifies different semantics than the standard library, 
and there you are actually expected to hold the lock if you want 
predictable scheduling. I hear pthread won't actually wake up any 
threads then (which wouldn't be able to make progress otherwise), but 
rather switch them from waiting on the cv to waiting on the mutex to 
avoid useless context switches; when the mutex is finally unlocked the 
thread will finally wake up.

Regards,
-- 
Agustín K-ballo Bergé.-
http://talesofcpp.fusionfenix.com