C++ C+中异步/未来的数量+；11

我正在尝试一个程序：

#include <iostream>
#include <thread>
#include <future>

int foo() {
  return 0;
}

int main(int argc, char* argv[]) {
  for (auto i = 0L; i < 10000; ++i) {
    auto f = std::async(foo);
    f.get();
  }
  return 0;
}

对我来说，这个程序崩溃了。我怀疑，同时实际运行的期货数量是有限制的。如果我将迭代次数减少到两个数量级，它就会工作

因此，有两个问题：

在C++11中实际运行futures是否有限制

为什么这段代码会崩溃？如果我在“async（）”之后立即显式执行“get（）”，那么它必须在下一次迭代之前完成future，这意味着一次只能运行一个future

更新

我已将代码简化为：

#include <future>

int main(int argc, char* argv[]) {
  for (auto i = 0L; i < 1000000; ++i) {
    auto f = std::async([](){ return 0; });
    f.get();
  }
  return 0;
}

#包括
int main（int argc，char*argv[]）{
用于（自动i=0L；i<1000000；++i）{
auto f=std:：async（[]（）{return 0；}）；
f、 get（）；
}
返回0；
}

对我来说，它仍然崩溃。它不会扔，我已经检查过了。但现在我有了一个可见的堆栈跟踪：

async.exe!_Mtx_unlock(_Mtx_internal_imp_t * * mtx) Line 229  C++
async.exe!std::_Mtx_unlockX(_Mtx_internal_imp_t * * _Mtx) Line 84  C++
async.exe!std::_Mutex_base::unlock() Line 47  C++
async.exe!std::unique_lock<std::mutex>::~unique_lock<std::mutex>() Line 284  C++
async.exe!std::_Associated_state<int>::_Set_value(int && _Val, bool _At_thread_exit) Line 358  C++
async.exe!std::_Packaged_state<int __cdecl(void)>::_Call_immediate() Line 569  C++
async.exe!std::_Async_state<int>::`std::U_Nil::ain::ain'::`3'::<lambda_A200A86DFF9A63A1>::operator()() Line 700  C++
async.exe!??$_ApplyX@X@?$_Callable_obj@V<lambda_A200A86DFF9A63A1>@?2???$?0V?$_Bind@$0A@XV<lambda_23AC5A2FBB53FD4D>@?5?main@U_Nil@std@@U23@U23@U23@U23@U23@U23@@std@@@?$_Async_state@H@std@@QEAA@$$QEAV?$_Bind@$0A@XV<lambda_23AC5A2FBB53FD4D>@?5?main@U_Nil@std@@U23@U23@U23@U23@U23@U23@@3@@Z@$0A@@std@@QEAAXXZ() Line 420  C++
async.exe!?_Do_call@?$_Func_impl@U?$_Callable_obj@V<lambda_A200A86DFF9A63A1>@?2???$?0V?$_Bind@$0A@XV<lambda_23AC5A2FBB53FD4D>@?5?main@U_Nil@std@@U23@U23@U23@U23@U23@U23@@std@@@?$_Async_state@H@std@@QEAA@$$QEAV?$_Bind@$0A@XV<lambda_23AC5A2FBB53FD4D>@?5?main@U_Nil@std@@U23@U23@U23@U23@U23@U23@@3@@Z@$0A@@std@@V?$allocator@V?$_Func_class@XU_Nil@std@@U12@U12@U12@U12@U12@U12@@std@@@2@XU_Nil@2@U42@U42@U42@U42@U42@U42@@std@@UEAAXXZ() Line 217  C++
async.exe!std::_Func_class<void,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>::operator()() Line 486  C++
async.exe!`Concurrency::details::_MakeVoidToUnitFunc'::`3'::<lambda_25D33530A43E1C90>::operator()() Line 1056  C++
async.exe!std::_Callable_obj<`Concurrency::details::_MakeVoidToUnitFunc'::`3'::<lambda_25D33530A43E1C90>,0>::_ApplyX<Concurrency::details::_Unit_type>() Line 420  C++
async.exe!std::_Func_impl<std::_Callable_obj<`Concurrency::details::_MakeVoidToUnitFunc'::`3'::<lambda_25D33530A43E1C90>,0>,std::allocator<std::_Func_class<Concurrency::details::_Unit_type,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil> >,Concurrency::details::_Unit_type,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>::_Do_call() Line 217  C++
async.exe!std::_Func_class<Concurrency::details::_Unit_type,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>::operator()() Line 486  C++
async.exe!`Concurrency::details::_Task_impl<Concurrency::details::_Unit_type>::_ScheduleTask'::`3'::<lambda_7D9BCD859405C05B>::operator()() Line 325  C++
async.exe!Concurrency::details::_PPLTaskHandle<`Concurrency::details::_Task_impl<Concurrency::details::_Unit_type>::_ScheduleTask'::`3'::<lambda_7D9BCD859405C05B> >::operator()() Line 72  C++
async.exe!Concurrency::details::_UnrealizedChore::_InvokeBridge<Concurrency::details::_PPLTaskHandle<`Concurrency::details::_Task_impl<Concurrency::details::_Unit_type>::_ScheduleTask'::`3'::<lambda_7D9BCD859405C05B> > >(Concurrency::details::_PPLTaskHandle<`Concurrency::details::_Task_impl<Concurrency::details::_Unit_type>::_ScheduleTask'::`3'::<lambda_7D9BCD859405C05B> > * _PChore) Line 4190  C++
async.exe!Concurrency::details::_UnrealizedChore::_UnstructuredChoreWrapper(Concurrency::details::_UnrealizedChore * pChore) Line 275  C++
async.exe!Concurrency::details::_PPLTaskChore::_DeletingChoreWrapper(Concurrency::details::_UnrealizedChore * pChore) Line 78  C++
async.exe!Concurrency::details::InternalContextBase::ExecuteChoreInline(Concurrency::details::WorkItem * pWork) Line 1600  C++
async.exe!Concurrency::details::InternalContextBase::Dispatch(Concurrency::DispatchState * pDispatchState) Line 1704  C++
async.exe!Concurrency::details::FreeThreadProxy::Dispatch() Line 191  C++
async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain(void * lpParameter) Line 173  C++
kernel32.dll!0000000076df652d()  Unknown
ntdll.dll!0000000076f2c521()  Unknown

async.exe_MTX-UNOLD（229）C++
async.exe！STD：：TyxMxxunLax（84，C++）
async.exe！STD：：μMutExxBase::unCuffor（47）C++
async.exe！STD:：UnQuiC++锁：：~
async.exe！STD：C++关联St:::StOySub值（int & & Valb，Boo-Y.TythRead Excel）358行C++
async.exe！STD：：包C++状态：：
async.exe！STD：：yasycStIt:：“STD：：Un:：AN：：AN”：：“3”：：：操作程序（）（700）C++（++）行
async.exe$_ApplyX@X@？$\可调用_obj@V@？2？？？$？0V？$\U绑定@$0A@XV@?5?main@U_Nil@性病@@U23@U23@U23@U23@U23@U23@@std@@？$\u异步_state@H@std@@QEAA@$$QEAV？$\u绑定@$0A@XV@?5?main@U_Nil@性病@@U23@U23@U23@U23@U23@U23@ @ 3 @ @ Z@ $0a@ @ STD@ @ QEAXXZ（）420行C++
async.exe_你打电话给@？$\u Func吗_impl@U？$\可调用_obj@V@？2？？？$？0V？$\U绑定@$0A@XV@?5?main@U_Nil@性病@@U23@U23@U23@U23@U23@U23@@std@@？$\u异步_state@H@std@@QEAA@$$QEAV？$\u绑定@$0A@XV@?5?main@U_Nil@性病@@U23@U23@U23@U23@U23@U23@@3@@Z@$0A@@std@@V$allocator@V？$\u Func_class@XU_Nil@性病@@U12@U12@U12@U12@U12@U12@@性病@@@2@XU_Nil@2@U42@U42@U42@U42@U42@U42@@std@@UEAAXXZ（）第217行C++
async.exe！St::AyHyffyCys:：（）（）486行C++
async.exe`并发：：细节：：“MykEvoIDoNoTunFunc”：：“3”：：：操作程序（）（1056）C++
async.exe！STD::AuCababLeObj:::Apple（420）C++
async.exe！STD：：{FunsIMPL::O-doAcLead（）217行C++
async.exe！St::AyHyffyCys:：（）（）486行C++
async.exe`并发：：细节：：TaskKIMPL:：“计划表：‘：‘3’：：：：操作程序（））（325）C++
async.exe！并发：：细节：：C++ PPLTASK句柄：：操作程序（）（72行C++）
async.exe！并发：：细节：C++未实现的琐碎：：
async.exe！并发：：细节：：不实现的琐碎：：OnNeultRealChrrReWrPrApp:（并发：：细节：未实现的CHORL *PCHOR）275行C++
async.exe！并发：：细节：：Apple PtasaskoRo:：OffeldCeleChrrrPraseRead（并发：：细节：：In untrueDeChan-PoRo.pCHORE）78行C++
async.exe！并发：：细节：内部CONTEXBASE:：ExuuTeTeReReIn行（并发：：细节：工作项*PoWork）1600行C++
async.exe！并发：：细节：NealCaleExbase:：Debug（并发：：Debug状态*pDeCtChestPurt+C++）1704行C++
async.exe！并发：：细节：FruteRealService：：Debug（）191行C++
async.exe！并发：：细节：THeReXPyth::TreRePro XORKEY（空洞*LPMODEL）173 C++
内核32.dll！0000000076df652d（）未知
ntdll.dll！0000000076f2c521（）未知

和线程：

Unflagged       1864    0   Worker Thread   ntdll.dll thread    ntdll.dll!0000000076f518ca  Normal
Unflagged       10964   0   Main Thread Main Thread async.exe!do_signal Normal
Unflagged       7436    0   Worker Thread   ntdll.dll thread    ntdll.dll!0000000076f52c1a  Normal
Unflagged       10232   0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!Concurrency::details::ThreadProxy::SuspendExecution   Normal
Unflagged   >   10624   0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!_Mtx_unlock   Normal
Unflagged       4756    0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!Concurrency::details::ThreadProxy::SuspendExecution   Normal
Unflagged       11100   0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!Concurrency::details::InternalContextBase::WaitForWork    Normal
Unflagged       6440    0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!std::vector<std::pair<void (__cdecl*)(void * __ptr64),void * __ptr64>,std::allocator<std::pair<void (__cdecl*)(void * __ptr64),void * __ptr64> > >::_Tidy Normal

未封装1864 0工作线程ntdll.dll线程ntdll.dll！00000000 76F518CA正常
未封装的10964 0主线程主线程async.exe！信号正常吗
未封装的7436 0工作线程ntdll.dll线程ntdll.dll！00000000 76F52C1A正常
未封装的10232 0工作线程async.exe！并发：：详细信息：：ThreadProxy：：ThreadProxyMain async.exe！并发：：详细信息：：线程代理：：挂起执行正常
Unflagged>10624 0工作线程async.exe！并发：：详细信息：：ThreadProxy：：ThreadProxyMain async.exe_Mtx_解锁正常
未封装的4756 0工作线程async.exe！并发：：详细信息：：ThreadProxy：：ThreadProxyMain async.exe！并发：：详细信息：：线程代理：：挂起执行正常
未封装的11100 0工作线程async.exe！并发：：详细信息：：ThreadProxy：：ThreadProxyMain async.exe！并发：：详细信息：：InternalContextBase：：WaitForWork正常
未封装的6440 0工作线程async.exe！并发：：详细信息：：ThreadProxy：：ThreadProxyMain async.exe！标准：：向量：：_正常

我使用的是VS 11.0.40825.2 PREREL

很明显，实现是有限制的，就像数组的大小是有限制的一样。如果启动策略为lauch:：async且系统无法启动新线程，则std:：async可能会发出错误信号“资源不可用\u重试”。但你不会犯这个错误

该程序不应该崩溃，对我来说也不会崩溃（VS11 x64，发布版本，相同的源代码和命令行）

我相信，即使没有

.get（）

，程序也不会同时执行多个异步操作。将future指定给局部变量，future在每次循环迭代中都会被销毁，从而迫使异步操作在下一次循环迭代中开始另一个操作之前完成

---

尝试用Try-catch将代码封装在main（）中，并检查它是否抛出std:：exception。这可能会给你一个暗示。 除此之外，VS中的C++11仍然是测试版

不，标准并没有说明线程支持库的限制（包括线程、未来等）

这取决于线程支持库和底层API的实现质量。正如你所说的：<代码> f GET（）/Cube >等待任务的补充（这个行为需要C++标准）。当库实现可能无法重用资源（如底层API的线程句柄）时，可能会导致系统资源不足和程序崩溃。这是图书馆实施的质量

Unflagged       1864    0   Worker Thread   ntdll.dll thread    ntdll.dll!0000000076f518ca  Normal
Unflagged       10964   0   Main Thread Main Thread async.exe!do_signal Normal
Unflagged       7436    0   Worker Thread   ntdll.dll thread    ntdll.dll!0000000076f52c1a  Normal
Unflagged       10232   0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!Concurrency::details::ThreadProxy::SuspendExecution   Normal
Unflagged   >   10624   0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!_Mtx_unlock   Normal
Unflagged       4756    0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!Concurrency::details::ThreadProxy::SuspendExecution   Normal
Unflagged       11100   0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!Concurrency::details::InternalContextBase::WaitForWork    Normal
Unflagged       6440    0   Worker Thread   async.exe!Concurrency::details::ThreadProxy::ThreadProxyMain    async.exe!std::vector<std::pair<void (__cdecl*)(void * __ptr64),void * __ptr64>,std::allocator<std::pair<void (__cdecl*)(void * __ptr64),void * __ptr64> > >::_Tidy Normal

g++ -std=c++11 -o main *.cpp 

g++ -std=c++11 -o main -lpthread *.cpp