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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.lang.c++
Subject: Re: signalling a condvar from inside vs. signalling a condvar von
 outside
Date: Thu, 24 Apr 2025 13:00:51 -0700
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On 4/23/2025 9:30 PM, Bonita Montero wrote:
> Am 23.04.2025 um 21:08 schrieb Chris M. Thomasson:
>> On 4/22/2025 10:13 PM, Bonita Montero wrote:
>>> Am 22.04.2025 um 23:36 schrieb Chris M. Thomasson:
>>>
>>>> It was created to try to _help_ with thundering herd. There can be 
>>>> some interesting issues... Think of pushing 12 items in the queue, 
>>>> broadcast inside the mutex, then 42 threads go onto the morph list. 
>>>> Depending on implementation, any new threads will not be able to 
>>>> acquire the mutex until those 42 threads are out of the morph. This 
>>>> can be bad for several reasons... If a thread is in the morph its in 
>>>> line waiting for it... So, it's a bit screwed and can't do anything 
>>>> else. If another thread can acquire the mutex before the morph is 
>>>> done, then it's basically thundering heard all over again. Fwiw, 
>>>> trying to scale mutexes is sort of odd anyway. We can make the best 
>>>> mutex ever, but they have trouble scaling.
>>>
>>> Do you have any source for your assumptions ?
>>>
>>
>> For trying to scale mutexes? Look up clever mutex solutions vs, say, 
>> RCU. They bite the dust.
> 
> You make random asssumptions. 

LOL! You are projecting yourself on me now.


> I've measured that there's not
> a thundering herd problem with condvars and glibc; look at the
> parallel posting in this thread.

Whatever you say man, whatever you say. wow.