boost和C++ 11線程兼容性

Question

有一個代碼，它可以在ubuntu下用boost線程正常運行。它是基本的只讀數據共享多線程。我嘗試使用C++ 11而不是boost，非常基本的轉換。代碼編譯但有微妙的錯誤。用C++ 11 std線程隨機崩潰。試圖使用valgrind drd，但很難讀取調試信息。有什麼想法嗎？

==19608== Conflicting load by thread 3 at 0x00643be8 size 8 
==19608== at 0x41CEBA: std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul>::operator()() (random.tcc:601) 
==19608== by 0x41CD6C: double std::generate_canonical<double, 53ul, std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul> >(std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul>&) (random.tcc:3475) 
==19608== by 0x41CB06: std::__detail::_Adaptor<std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul>, double>::operator()() (random.h:190) 
==19608== by 0x41C877: double std::normal_distribution<double>::operator()<std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul> >(std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul>&, std::normal_distribution<double>::param_type const&) (random.tcc:1950) 
==19608== by 0x41C688: double std::normal_distribution<double>::operator()<std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul> >(std::subtract_with_carry_engine<unsigned int, 24ul, 10ul, 24ul>&) (random.h:2196) 
==19608== by 0x41C379: nrand(double, double) (NRand.cpp:8) 
==19608== by 0x416F78: ClassDef::set_x() (LoanDef.h:407) 
==19608== by 0x4168CA: Sim(std::vector<ClassDef, std::allocator<ClassDef> >&, Assumption&, std::unordered_map<std::string, std::vector<double, std::allocator<double> >, std::hash<std::string>, std::equal_to<std::string>, std::allocator<std::pair<std::string const, std::vector<double, std::allocator<double> > > > >&, unsigned int, NextStepCalcML&, std::vector<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >, std::allocator<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > > > >&, unsigned int, unsigned int) (NewSim.cpp:105) 
==19608== by 0x411A09: _ZNSt12_Bind_simpleIFPFvRSt6vectorI7LoanDefSaIS1_EER10AssumptionRSt13unordered_mapISsS0_IdSaIdEESt4hashISsESt8equal_toISsESaISt4pairIKSsS9_EEEjR14NextStepCalcMLRS0_IS0_IS9_SaIS9_EESaISN_EEjjESt17reference_wrapperIS3_EST_IS5_EST_ISI_EjST_ISK_EST_ISP_EjjEE9_M_invokeIILm0ELm1ELm2ELm3ELm4ELm5ELm6ELm7EEEEvSt12_Index_tupleIIXspT_EEE (functional:1732) 
==19608== by 0x4116AE: std::_Bind_simple<void (*()(std::reference_wrapper<std::vector<LoanDef, std::allocator<LoanDef> > >, std::reference_wrapper<Assumption>, std::reference_wrapper<std::unordered_map<std::string, std::vector<double, std::allocator<double> >, std::hash<std::string>, std::equal_to<std::string>, std::allocator<std::pair<std::string const, std::vector<double, std::allocator<double> > > > > >, unsigned int, std::reference_wrapper<NextStepCalcML>, std::reference_wrapper<std::vector<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >, std::allocator<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > > > > >, unsigned int, unsigned int))(std::vector<LoanDef, std::allocator<ClassDef> >&, Assumption&, std::unordered_map<std::string, std::vector<double, std::allocator<double> >, std::hash<std::string>, std::equal_to<std::string>, std::allocator<std::pair<std::string const, std::vector<double, std::allocator<double> > > > >&, unsigned int, NextStep&, std::vector<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >, std::allocator<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > > > >&, unsigned int, unsigned int)>::operator()() (functional:1720) 
==19608== by 0x411647: std::thread::_Impl<std::_Bind_simple<void (*()(std::reference_wrapper<std::vector<ClassDef, std::allocator<ClassDef> > >, std::reference_wrapper<Assumption>, std::reference_wrapper<std::unordered_map<std::string, std::vector<double, std::allocator<double> >, std::hash<std::string>, std::equal_to<std::string>, std::allocator<std::pair<std::string const, std::vector<double, std::allocator<double> > > > > >, unsigned int, std::reference_wrapper<NextStep>, std::reference_wrapper<std::vector<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >, std::allocator<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > > > > >, unsigned int, unsigned int))(std::vector<LoanDef, std::allocator<LoanDef> >&, Assumption&, std::unordered_map<std::string, std::vector<double, std::allocator<double> >, std::hash<std::string>, std::equal_to<std::string>, std::allocator<std::pair<std::string const, std::vector<double, std::allocator<double> > > > >&, unsigned int, NextStep&, std::vector<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >, std::allocator<std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > > > >&, unsigned int, unsigned int)> >::_M_run() (thread:115) 

謝謝。順便說一句，我試圖使用這個隨機頭文件，我寫道，不知道在多線程環境下它是否安全。它曾用於提升工作正常。

myrand.hpp

#ifndef NRAND_H 
#define NRAND_H 
#include <random> 

double nrand(double mean = 0., double sd = 1.); 
double urand(double a=0., double b=0.); 

#endif 

和myrand.cpp

#include "NRand.h" 
using namespace std; 

double nrand(double mean, double sd) { 
    static random_device rd; 
    static subtract_with_carry_engine<unsigned,24,10,24> e(rd()); 
    normal_distribution<> dist(mean, sd); 
    return dist(e); 
} 

double urand(double a, double b) { 
    static random_device rd; 
    static subtract_with_carry_engine<unsigned,24,10,24> e(rd()); 
    uniform_real_distribution<> dist(a, b); 
    return dist(e); 
} 

千恩萬謝。

Answer 1

恕我直言，你的代碼不是線程安全的，因此不應該在C++ 11下正常工作。我認爲問題是static變量rd和e是全局變量，但不受保護（通過互斥鎖），因此併發調用將競爭。

大概，你可以通過使這些變量變成thread_local來使這段代碼線程安全，但我沒有經驗。