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Groups > comp.lang.c++ > #120426
| From | Paavo Helde <eesnimi@osa.pri.ee> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: a try_lock pattern... |
| Date | 2024-09-28 10:53 +0300 |
| Organization | A noiseless patient Spider |
| Message-ID | <vd8cmd$159kt$3@dont-email.me> (permalink) |
| References | <vd8an7$15ff9$1@dont-email.me> |
On 28.09.2024 10:20, Chris M. Thomasson wrote:
> This is just a quick test of my try_lock pattern thing. ct_shared::m_b
> counts how many times extra work was able to be done instead of spinning
> on the ct_shared::m_lock_a mutex. Take careful notice of the
> ct_shared::work_a_lock() function.
>
> Can you test it out? A large number for ct_shared::m_b is ideal. It
> means extra work was being done. Avoids spinning in an interesting way.
>
> my crude code, can you compile and run it okay? Thanks:
> _________________________
> #include <cassert>
> #include <iostream>
> #include <atomic>
> #include <mutex>
> #include <functional>
> #include <thread>
>
>
> #define CT_THREADS 10
> #define CT_ITERS 1000000
>
>
> // Test Threads...
> struct ct_shared
> {
> long m_a;
> unsigned long m_b;
> std::mutex m_lock_a;
> std::mutex m_lock_b;
>
> ct_shared() : m_a(0), m_b(0) {}
>
>
> bool work_b_try(unsigned long addend)
> {
> if (! m_lock_b.try_lock())
> {
> return false;
> }
>
> {
> m_b += addend;
> }
>
> m_lock_b.unlock();
>
> return true;
> }
>
> // The main pattern...
> void work_a_lock()
> {
> while (! m_lock_a.try_lock())
> {
> if (! work_b_try(1))
> {
> m_lock_a.lock();
> break;
> }
> }
> }
>
> void work_a_unlock()
> {
> m_lock_a.unlock();
> }
>
> void work_a(long addend)
> {
> work_a_lock();
>
> {
> m_a += addend;
> }
>
> work_a_unlock();
> }
> };
>
>
> // Test out a pattern...
> void
> ct_thread(
> ct_shared& shared
> ) {
> for (unsigned long i = 0; i < CT_ITERS; ++i)
> {
> shared.work_a(1);
> std::this_thread::yield();
> shared.work_a(-1);
> }
> }
>
>
> // Get things going...
> int
> main()
> {
> std::cout << "ct try_lock pattern Test...\n\n";
>
> {
> ct_shared shared;
>
> std::thread threads[CT_THREADS];
>
> // Create threads...
> std::cout << "launching threads..." << std::endl;
>
> for (unsigned long i = 0; i < CT_THREADS; ++i)
> {
> threads[i] = std::thread(ct_thread, std::ref(shared));
>
> }
>
> std::cout << "processing...\n" << std::endl;
>
> // Join threads...
> for (unsigned long i = 0; i < CT_THREADS; ++i)
> {
> threads[i].join();
> }
>
> // Sanity check...
> {
> std::cout << "shared.m_a = " << shared.m_a << "\n";
> std::cout << "shared.m_b = " << shared.m_b << "\n";
>
> if (shared.m_a != 0)
> {
> std::cout << "\n\nAAHHHH SHHHIIITT!!\n";
> }
>
> }
> }
>
> std::cout << "\nct try_lock pattern Test completed.\n\n";
>
> return 0;
> }
> _________________________
>
>
> What results do you get for ct_shared::m_b? Here is a result I get:
> _____________________________
> ct try_lock pattern Test...
>
> launching threads...
> processing...
>
> shared.m_a = 0
> shared.m_b = 8664093
>
> ct try_lock pattern Test completed.
> _____________________________
>
> Well, shared.m_b is a high number... That is a lot potential kernel
> calls that were skipped in favor of real work.
>
> Any thoughts? Thanks.
Seems to compile and work fine with VS2022 on Windows x86_64
ct try_lock pattern Test...
launching threads...
processing...
shared.m_a = 0
shared.m_b = 6976047
ct try_lock pattern Test completed.
Back to comp.lang.c++ | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-28 00:20 -0700
Re: a try_lock pattern... Paavo Helde <eesnimi@osa.pri.ee> - 2024-09-28 10:53 +0300
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-28 12:18 -0700
Re: a try_lock pattern... scott@slp53.sl.home (Scott Lurndal) - 2024-09-29 18:03 +0000
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-29 20:15 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-29 13:18 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-30 07:53 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-30 16:41 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-01 06:45 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 11:44 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-01 21:40 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 12:48 -0700
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-29 12:55 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-28 10:40 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-28 12:55 -0700
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-28 16:30 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-29 08:15 +0200
Re: a try_lock pattern... Muttley@dastardlyhq.com - 2024-09-29 09:01 +0000
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-29 12:54 +0200
Re: a try_lock pattern... Muttley@dastardlyhq.com - 2024-09-29 14:56 +0000
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-29 17:20 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-29 13:24 -0700
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-29 14:03 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-30 07:51 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 12:34 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-02 00:58 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-29 14:45 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-30 07:52 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-30 18:11 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-01 06:47 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 11:45 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-09-30 08:02 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-30 16:37 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-01 09:17 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 11:49 -0700
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 12:37 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-02 01:30 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 16:37 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-02 01:43 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 18:20 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-02 03:24 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-01 18:25 -0700
Re: a try_lock pattern... Bonita Montero <Bonita.Montero@gmail.com> - 2024-10-02 04:13 +0200
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-10-02 16:57 -0700
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-29 19:53 -0700
Re: a try_lock pattern... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-09-29 12:58 -0700
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