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Re: counting_semaphore question

From "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups comp.lang.c++
Subject Re: counting_semaphore question
Date 2024-09-16 14:22 -0700
Organization A noiseless patient Spider
Message-ID <vca7hs$32c6u$1@dont-email.me> (permalink)
References (1 earlier) <vbs01c$3j5mc$1@raubtier-asyl.eternal-september.org> <vbs0tm$3jf62$1@dont-email.me> <vbs1al$3jgnp$1@raubtier-asyl.eternal-september.org> <vbs2fm$3jp23$1@dont-email.me> <vbs95s$3l7ms$1@dont-email.me>

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On 9/11/2024 7:23 AM, David Brown wrote:
> On 11/09/2024 14:29, Muttley@dastardlyhq.com wrote:
>> On Wed, 11 Sep 2024 14:10:05 +0200
>> Bonita Montero <Bonita.Montero@gmail.com> boringly babbled:
>>> Am 11.09.2024 um 14:03 schrieb Muttley@dastardlyhq.com:
>>>
>>>> What upper limit? The max number of threads allowed in the protected 
>>>> section
>>>> above is 2, not 10. Or do you mean it'll only count up to 10 threads 
>>>> waiting
>>>> and ignore any beyond that? What happens if thread 11 comes along?
>>>
>>> The static parmeter is the maximum counter and the the two is the
>>> initial counter. So two threads can currently acquire that semaphore.
>>
>> Sorry, I still don't get it. What do you mean by maximum counter?
>>
>> Maximum threads that can wait on the semaphore and 11 gets an error?
>> Maximum threads that can ever access the protected section and after 
>> 10 have
>> accessed it the section is blocked to all threads?
>>
> 
> You are talking about a counting semaphore here - the number will be the 
> maximum value of the count.  (The actual maximum value could be bigger 
> than the template parameter, but not smaller than it.)  If this maximum 
> value is 10, then you can acquire the semaphore 10 times without 
> blocking - any future acquires will block until there are releases.
> 
> Semaphores can be acquired and released by any threads - one thread can 
> acquire often, another thread can release them, or you can have any 
> combination.  They are not used for protection sections or data - they 
> are used as signalling mechanisms.  One or more "producer" thread might 
> make objects, and one or more "consumer" threads used them, in which 
> case your 10 here is the maximum number of these objects that will be 
> buffered up at a time.

[...]

Think of creating a queue with 100,000 elements in it. The semaphore to 
protect this queue should have an initial state of 100,000. The least 
min value, should be high because the queue might have 1.9 million 
elements in there. So, for this queue:

std::counting_semaphore<PTRDIFF_MAX> sem(100000);

right? There are 100000 elements in the queue because its initialized 
that way. A single thread can pop and work on 100000 elements before it 
blocks on a queue empty condition.

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counting_semaphore question Muttley@dastardlyhq.com - 2024-09-11 10:15 +0000
  Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-11 13:48 +0200
    Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-11 12:03 +0000
      Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-11 14:10 +0200
        Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-11 12:29 +0000
          Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-11 15:54 +0200
            Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-11 14:12 +0000
          Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-11 16:23 +0200
            Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-16 14:22 -0700
              Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-17 09:22 +0200
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-17 11:56 -0700
                Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-18 09:32 +0200
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-19 12:57 +0200
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-19 13:01 +0200
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-19 12:09 -0700
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-19 13:27 -0700
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-19 13:30 -0700
          Re: counting_semaphore question Ben Bacarisse <ben@bsb.me.uk> - 2024-09-12 11:25 +0100
            Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-12 11:00 +0000
              Re: counting_semaphore question Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-09-12 07:34 -0700
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-12 14:53 +0000
                Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-13 08:39 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-13 07:26 +0000
                Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-13 12:54 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-13 13:21 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-13 15:29 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-13 13:41 +0000
                Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-15 17:33 +0200
                Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-13 16:46 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-13 14:59 +0000
                Re: counting_semaphore question Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-09-13 07:43 -0700
        Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-11 13:51 -0700
          Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-12 04:21 +0200
            Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-12 11:57 -0700
              Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-13 14:29 +0200
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-13 12:44 -0700
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-14 01:43 +0200
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-13 22:21 -0700
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-14 12:07 -0700
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-14 09:18 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-14 11:40 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-14 10:58 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-14 13:15 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-14 15:13 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-14 17:26 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-14 15:48 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-14 17:50 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-14 15:55 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-14 17:57 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-15 09:05 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-15 11:48 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-15 09:52 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-15 14:50 +0200
                Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-15 15:28 +0000
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-16 05:02 +0200
                Re: counting_semaphore question scott@slp53.sl.home (Scott Lurndal) - 2024-09-15 16:27 +0000
                Re: counting_semaphore question scott@slp53.sl.home (Scott Lurndal) - 2024-09-15 16:26 +0000
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-14 12:12 -0700
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-14 17:21 -0700
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-15 07:11 +0200
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-14 22:20 -0700
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-15 09:35 +0200
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-15 12:59 -0700
                Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-16 05:04 +0200
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-16 13:30 -0700
                Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-14 12:09 -0700
  Re: counting_semaphore question Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-09-11 07:37 -0700
    Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-11 15:03 +0000
      Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-11 17:27 +0200
        Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-11 16:04 +0000
          Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-11 18:16 +0200
            Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-11 18:16 +0000
              Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-12 04:20 +0200
          Re: counting_semaphore question "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-12 13:00 -0700
      Re: counting_semaphore question Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-09-11 20:56 -0700
        Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-12 07:43 +0000
          Re: counting_semaphore question David Brown <david.brown@hesbynett.no> - 2024-09-12 13:30 +0200
            Re: counting_semaphore question Muttley@dastardlyhq.com - 2024-09-12 14:48 +0000
          Re: counting_semaphore question Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-12 15:38 +0200
          Re: counting_semaphore question Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-09-12 07:05 -0700

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