1. C++ / Говнокод #17725

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    #include <ppl.h>
#include <windows.h>
#include <ppltasks.h>
#include <iostream>
#include <vector>

using namespace Concurrency;
using namespace std;

CRITICAL_SECTION cs6;

int main(int argc, char* argv[])
{
	size_t concurentThreadsSupported = std::thread::hardware_concurrency();
	cout << concurentThreadsSupported << endl;
	//deadlock hazard increased with concurentThreadsSupported decreasing

	size_t taskAmountForWasteVirtualCores = concurentThreadsSupported - 1;//must be equal to (virtual processor thread amount from Concurrency::IResourceManager) - 1
	vector<task<void>> t;
	for (size_t i = 0; i<taskAmountForWasteVirtualCores; ++i)
		t.push_back(create_task([]{
			Sleep(INFINITE);//some very long IO operation or deadlocked by EnterCriticalSection or sql transaction or other
		}));
	Sleep(1000);
    cout << "another way:" << endl;
    InitializeCriticalSection(&cs6);
    auto locker = create_task([]{
        cout << "locker" << endl;
        EnterCriticalSection(&cs6);//same as begin sql transaction
        cout << "locker entered cs 6" << endl;
        Concurrency::wait(500);//Deadlock by any concurrency context switching directly or indirectly by std or MFC (events, mutex, etc)
        cout << "locker played" << endl;
        LeaveCriticalSection(&cs6);//same as end sql transaction
        cout << "~locker ok" << endl;
    });
    auto locked = create_task([]{
        cout << "locked" << endl;
        EnterCriticalSection(&cs6);//same as begin sql transaction
        cout << "locked entered cs 6" << endl;
        Concurrency::wait(500);
        cout << "locked played" << endl;
        LeaveCriticalSection(&cs6);//same as end sql transaction
        cout << "~locked ok" << endl;
    });
	Sleep(1000);
	cout << "FAIL" << endl;
	return 0;
}

    Нашел дидлок)
    http://rextester.com/KHC72232
    http://rextester.com/EMG65441

    Запостил: laMer007, 04 Марта 2015

    Комментарии (11) RSS

    • ava laMer007 04.03.2015 16:48 # 0 

      #include <ppl.h>
#include <windows.h>
#include <ppltasks.h>
#include <iostream>
#include <vector>

using namespace Concurrency;
using namespace std;

int main(int argc, char* argv[])
{
	size_t concurentThreadsSupported = std::thread::hardware_concurrency();
	cout << concurentThreadsSupported << endl;
	//deadlock hazard increased with concurentThreadsSupported decreasing

	size_t taskAmountForWasteVirtualCores = concurentThreadsSupported - 1;//must be equal to (virtual processor thread amount from Concurrency::IResourceManager) - 1
	vector<task<void>> t;
	for (size_t i = 0; i<taskAmountForWasteVirtualCores; ++i)
		t.push_back(create_task([]{
			Sleep(INFINITE);//some very long IO operation or deadlocked by EnterCriticalSection or sql transaction or other
		}));
	Sleep(1000);
    HANDLE event = CreateEventA(nullptr, 1, 0, "I am bad guy");
    auto locked = create_task([event]{
        cout << "unlocker" << endl;
        Concurrency::wait(100);
        SetEvent(event);
        cout << "~unlocker ok" << endl;
    });
    auto locker = create_task([event]{
        cout << "locked" << endl;
        WaitForSingleObject(event, INFINITE);
        cout << "~locked ok" << endl;
    });
	Sleep(1000);
	cout << "FAIL" << endl;
	return 0;
}
      Что там майкрософт то курило? Как таких локов избежать, если кучу потоков ждет завершения sql транзакции как в нульпосте (для простоты примера критические секции юзаем)?
      Ответить

      • ava laMer007 04.03.2015 17:12 # 0

        Именно из-за второго и вешались все потоки в приложении. На самом деле не все, но в целом казалось что все. Просто те что не вешались в данный момент не выполняли работы.
        Ответить

    • ava laMer007 04.03.2015 19:12 # 0

      Если кому интересно, то проблему собираюсь решить так:
      http://rextester.com/AKZL36928
      class scoped_oversubcription_token
{
public:
	scoped_oversubcription_token()
	{
		Concurrency::Context::CurrentContext()->Oversubscribe(true);
	}
	~scoped_oversubcription_token()
	{
		Concurrency::Context::CurrentContext()->Oversubscribe(false);
	}
};
using namespace Concurrency;
using namespace std;
CRITICAL_SECTION cs6;
int main(int argc, char* argv[])
{
	size_t concurentThreadsSupported = std::thread::hardware_concurrency();
	cout << concurentThreadsSupported << endl;
	size_t taskAmountForWasteVirtualCores = concurentThreadsSupported - 1;//must be equal to (virtual processor thread amount from Concurrency::IResourceManager) - 1
	vector<task<void>> t;
	for (size_t i = 0; i<taskAmountForWasteVirtualCores; ++i)
		t.push_back(create_task([]{
            scoped_oversubcription_token t;
			Sleep(INFINITE);//some very long IO operation or deadlocked by EnterCriticalSection or sql transaction or other
		}));
	Sleep(1000);
      Ответить

      • ava laMer007 04.03.2015 19:13 # 0 

        InitializeCriticalSection(&cs6);
    auto locker = create_task([]{
        scoped_oversubcription_token t;
        cout << "locker" << endl;
        EnterCriticalSection(&cs6);//same as begin sql transaction
        cout << "locker entered cs 6" << endl;
        Concurrency::wait(500);//Deadlock by any concurrency context switching directly or indirectly by std or MFC (events, mutex, etc)
        cout << "locker played" << endl;
        LeaveCriticalSection(&cs6);//same as end sql transaction
        cout << "~locker ok" << endl;
    });
    auto locked = create_task([]{
        scoped_oversubcription_token t;
        cout << "locked" << endl;
        EnterCriticalSection(&cs6);//same as begin sql transaction
        cout << "locked entered cs 6" << endl;
        Concurrency::wait(500);
        cout << "locked played" << endl;
        LeaveCriticalSection(&cs6);//same as end sql transaction
        cout << "~locked ok" << endl;
    });
	Sleep(1000);
	cout << "OK" << endl;
	return 0;
}
        Ответить

      • ava OCEHHuu_nemyx 16.10.2020 13:51 # 0

        Ну как, решил?
        Ответить

    • ava TarasB 04.03.2015 22:18 # +5

      дилдок
      Ответить

    • ava blackhearted 05.03.2015 14:26 # +2

      дилдок поищи
      Ответить

    • ava laMer007 17.03.2015 23:46 # 0

      От Oversubscribe вообще все поломалось
      Ответить

    • ava guest 01.04.2017 10:43 # −15

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      Ответить

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