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Re: ???The pool of talented C++ developers is running dry???

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c++
Subject Re: ???The pool of talented C++ developers is running dry???
Date 2022-11-11 08:10 +0100
Organization A noiseless patient Spider
Message-ID <tkksi3$pom6$1@dont-email.me> (permalink)
References (6 earlier) <diUaL.5684$BaF9.4221@fx39.iad> <tkie4g$h5am$1@dont-email.me> <tkjkqu$k10j$3@dont-email.me> <tkjnqt$k9i0$1@dont-email.me> <tkjocq$kaut$1@dont-email.me>

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On 10/11/2022 21:53, Chris M. Thomasson wrote:
> On 11/10/2022 12:44 PM, David Brown wrote:
>> On 10/11/2022 20:53, Chris M. Thomasson wrote:
>>> On 11/10/2022 12:52 AM, David Brown wrote:

>>> If the result of is_lock_free is not true, then you should really 
>>> think about digging into how the locking is actually implemented. 
>>> Hash based address locking is one simple way to do it. Fwiw, I 
>>> created one called multi-mutex:
>>>
>>> https://groups.google.com/g/comp.lang.c++/c/sV4WC_cBb9Q/m/Ti8LFyH4CgAJ
>>
>> Hash-based arrays of locks are as bad as a single lock for all 
>> atomics, in that it does not work unless it is a proper OS lock.  The 
>> larger your array of locks, the lower your chances of problems, but it 
>> all comes down to one thing - are your locks safe or not?
> 
> Well, my multi-mutex uses std::mutex as elements of its vector of locks. 
> It hashes an address into said table. So, it's only as good as the 
> implementation of std::mutex...
> 
> std::vector<std::mutex> m_locks;
> 
> Fair enough?
> 

As long as std::mutex is a wrapper for a real OS mutex, that will be 
fine (after padding for cache line sizes).

The problem with the atomics library in gcc is not the array of locks or 
the hashing on address, but that it doesn't use /real/ locks.

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Thread

“The pool of talented C++ developers is running dry” Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-03 14:30 -0500
  Re: “The pool of talented C++ developers is running dry” "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-03 13:03 -0700
    Re: “The pool of talented C++ developers is running dry” "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-03 13:04 -0700
      Re: “The pool of talented C++ developers is running dry” Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-03 16:07 -0500
    Re: “The pool of talented C++ developers is running dry” Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-03 16:05 -0500
      Re: “The pool of talented C++ developers is running dry” "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-03 14:25 -0700
        Re: “The pool of talented C++ developers is running dry” Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-05 14:12 -0500
          Re: “The pool of talented C++ developers is running dry” "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-05 14:20 -0700
      Re: “The pool of talented C++ developers is running dry” Bonita Montero <Bonita.Montero@gmail.com> - 2022-11-04 09:24 +0100
  Re: “The pool of talented C++ developers is running dry” Vir Campestris <vir.campestris@invalid.invalid> - 2022-11-05 21:42 +0000
  Re: “The pool of talented C++ developers is running dry” "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-06 11:55 -0800
  Re: “The pool of talented C++ developers is running dry” Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-11-08 02:44 -0800
    Re: ???The pool of talented C++ developers is running dry??? Juha Nieminen <nospam@thanks.invalid> - 2022-11-08 11:29 +0000
      Re: ???The pool of talented C++ developers is running dry??? Öö Tiib <ootiib@hot.ee> - 2022-11-08 03:54 -0800
        Re: ???The pool of talented C++ developers is running dry??? Stuart Redmann <DerTopper@web.de> - 2022-11-08 14:26 +0100
          Re: ???The pool of talented C++ developers is running dry??? Öö Tiib <ootiib@hot.ee> - 2022-11-09 00:22 -0800
        Re: ???The pool of talented C++ developers is running dry??? Juha Nieminen <nospam@thanks.invalid> - 2022-11-08 15:16 +0000
      Re: ???The pool of talented C++ developers is running dry??? Bonita Montero <Bonita.Montero@gmail.com> - 2022-11-08 14:52 +0100
      Re: ???The pool of talented C++ developers is running dry??? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2022-11-08 22:48 +0000
      Re: ???The pool of talented C++ developers is running dry??? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-08 15:39 -0800
        Re: ???The pool of talented C++ developers is running dry??? David Brown <david.brown@hesbynett.no> - 2022-11-09 09:29 +0100
          Re: ???The pool of talented C++ developers is running dry??? scott@slp53.sl.home (Scott Lurndal) - 2022-11-09 14:39 +0000
            Re: ???The pool of talented C++ developers is running dry??? David Brown <david.brown@hesbynett.no> - 2022-11-09 17:05 +0100
              Re: ???The pool of talented C++ developers is running dry??? scott@slp53.sl.home (Scott Lurndal) - 2022-11-09 17:58 +0000
          Re: ???The pool of talented C++ developers is running dry??? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-09 11:47 -0800
            Re: ???The pool of talented C++ developers is running dry??? scott@slp53.sl.home (Scott Lurndal) - 2022-11-09 20:43 +0000
              Re: ???The pool of talented C++ developers is running dry??? David Brown <david.brown@hesbynett.no> - 2022-11-10 09:52 +0100
                Re: ???The pool of talented C++ developers is running dry??? Michael S <already5chosen@yahoo.com> - 2022-11-10 03:07 -0800
                Re: ???The pool of talented C++ developers is running dry??? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-10 11:53 -0800
                Re: ???The pool of talented C++ developers is running dry??? David Brown <david.brown@hesbynett.no> - 2022-11-10 21:44 +0100
                Re: ???The pool of talented C++ developers is running dry??? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-10 12:53 -0800
                Re: ???The pool of talented C++ developers is running dry??? scott@slp53.sl.home (Scott Lurndal) - 2022-11-10 21:20 +0000
                Re: ???The pool of talented C++ developers is running dry??? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-10 13:23 -0800
                Re: ???The pool of talented C++ developers is running dry??? David Brown <david.brown@hesbynett.no> - 2022-11-11 08:10 +0100
                Re: ???The pool of talented C++ developers is running dry??? Öö Tiib <ootiib@hot.ee> - 2022-11-11 01:45 -0800
              Re: ???The pool of talented C++ developers is running dry??? Michael S <already5chosen@yahoo.com> - 2022-11-10 03:14 -0800
      Re: ???The pool of talented C++ developers is running         dry??? Sam <sam@email-scan.com> - 2022-11-09 07:59 -0500

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