我有一个解决这些二维迷宫的程序，对我来说效果很好，但我用gprof（以及@ jrfonseca的幻想gprof2dot）对它进行了分析，在我看来它正在拍摄一些操作很难，并决定进行一些并行尝试。
基本上在消耗50％（cpu？）时间的函数中，我有两种并行选择（单个队列的多个使用者和相同函数的并行调用具有相似的不相等的参数）但最初想独立完成这两项工作以检查最好的假设，哪一个更好，我不总是做C ++代码，并通过在互联网上搜索如何让std::thread返回一个价值我在std::future的建议上读了一个很好的答案，然后我把它复制到了我的代码中，所以请你知道这是什么意思......
bash-4.3$ sh build.sh
In file included from find_path.cpp:6:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/Xco
deDefault.xctoolchain/usr/bin/../include/c++/v1/future:371:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/
usr/bin/../include/c++/v1/thread:337:5: error:
attempt to use a deleted function
__invoke(_VSTD::move(_VSTD::get<0>(__t)), _VSTD::move(_VSTD::get<_In...
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/
usr/bin/../include/c++/v1/thread:347:5:
in instantiation of function template specialization
'std::__1::__thread_execute<void
(*)(std::__1::priority_queue<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::vector<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::allocator<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > > >, NearerTarget> &,
std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > &, std::__1::pair<int,
int> &, int, int, int, int, unsigned char *,
std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > &, int, int,
std::__1::promise<bool> &&),
std::__1::reference_wrapper<std::__1::priority_queue<std::__1::vector<std
::__1::pair<int,
int>, std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::vector<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::allocator<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > > >, NearerTarget> >,
std::__1::reference_wrapper<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > >,
std::__1::reference_wrapper<std::__1::pair<int, int> >, int, int, int,
int, const unsigned char *,
std::__1::reference_wrapper<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > >, int, int,
std::__1::promise<bool> , 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12>'
requested here
__thread_execute(*__p, _Index());
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/
usr/bin/../include/c++/v1/thread:359:42: note:
in instantiation of function template specialization
'std::__1::__thread_proxy<std::__1::tuple<void
(*)(std::__1::priority_queue<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::vector<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::allocator<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > > >, NearerTarget> &,
std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > &, std::__1::pair<int,
int> &, int, int, int, int, unsigned char *,
std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > &, int, int,
std::__1::promise<bool> &&),
std::__1::reference_wrapper<std::__1::priority_queue<std::__1::vector<std
::__1::pair<int,
int>, std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::vector<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::allocator<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > > >, NearerTarget> >,
std::__1::reference_wrapper<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > >,
std::__1::reference_wrapper<std::__1::pair<int, int> >, int, int, int,
int, const unsigned char *,
std::__1::reference_wrapper<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > >, int, int,
std::__1::promise<bool> > >' requested here
int __ec = pthread_create(&__t_, 0, &__thread_proxy<_Gp>, __p.get());
^
find_path.cpp:258:25: note: in instantiation of function template specializatio
n
'std::__1::thread::thread<void
(*)(std::__1::priority_queue<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::vector<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::allocator<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > > >, NearerTarget> &,
std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > &, std::__1::pair<int,
int> &, int, int, int, int, unsigned char *,
std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > &, int, int,
std::__1::promise<bool> &&),
std::__1::reference_wrapper<std::__1::priority_queue<std::__1::vector<std
::__1::pair<int,
int>, std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::vector<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > >,
std::__1::allocator<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > > >, NearerTarget> >,
std::__1::reference_wrapper<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > >,
std::__1::reference_wrapper<std::__1::pair<int, int> >, int &, int &,
const int &, const int &, const unsigned char *&,
std::__1::reference_wrapper<std::__1::vector<std::__1::pair<int, int>,
std::__1::allocator<std::__1::pair<int, int> > > >, const int &, int,
std::__1::promise<bool> , void>' requested here
std::thread n(&move, std::ref(active_paths),
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/
usr/bin/../include/c++/v1/type_traits:1043:5: note:
'~__nat' has been explicitly marked deleted here
~__nat() = delete;
^
1 error generated.
bash-4.3$
......在这种情况下？
一些find_path.cpp：
1 // For 'assert(expression)'.
2 #include <cassert>
3 // For 'std::abs' (absolute value function, integers version)'.
4 #include <cstdlib>
5 // For 'std::promise' and 'std::future'.
6 #include <future> // <--
7 // For 'std::mutex'.
8 #include <mutex>
9 // For 'std::priority_queue'.
10 #include <queue>
11 // For 'std::move'.
12 #include <utility>
13 // For 'std::vector'.
14 #include <vector>
15 // For 'std::thread'.
16 #include <thread>
17 // For 'std::get', 'std::make_tuple' and 'std::tuple'.
18 #include <tuple>
更多：
242 // Do not add new paths unless deemed necessary.
243 bool add_north_move, add_west_move, add_south_move, add_east_move;
244 add_north_move = add_west_move = add_south_move = add_east_move =
245 0;
246
247 // Another helper.
248 std::vector < std::pair < int, int > > active_paths_top =
249 active_paths.top();
250 std::pair < int, int > active_paths_top_back =
251 active_paths_top.back();
252
253 // Directions clockwise (0: 'N', 1: 'E', 2: 'S', 3: 'W').
254 int direction = 0;
255
256 std::promise < bool > n_p;
257 auto n_f = n_p.get_future();
258 std::thread n(&move, std::ref(active_paths), // <--
259 std::ref(active_paths_top),
260 std::ref(active_paths_top_back), new_move_back_x, new_move_back_y,
261 nMapWidth, nMapHeight, pMap, std::ref(north_move), nOutBufferSize, direction++, std::move(n_p)
262 );
263 std::promise < bool > e_p;
264 auto e_f = e_p.get_future();
265 std::thread e(&move, std::ref(active_paths),
266 std::ref(active_paths_top),
267 std::ref(active_paths_top_back), new_move_back_x, new_move_back_y,
268 nMapWidth, nMapHeight, pMap, std::ref(east_move), nOutBufferSize, direction++, std::move(e_p)
269 );
void move(12)中的内容：
108 void move(std::priority_queue <
109 std::vector < std::pair < int, int > >,
110 std::vector < std::vector < std::pair < int, int > > >,
111 NearerTarget
112 > & active_paths,
113 std::vector < std::pair < int, int > > & active_paths_top,
114 std::pair < int, int > & active_paths_top_back, int new_move_back_x, int new_move_back_y,
115 int map_width, int map_height, unsigned char * map, std::vector < std::pair < int, int > > & move,
116 int out_buffer_size, int direction,
117 std::promise < bool > && add_move) {
118 assert(-1 < direction && 4 > direction);
119 std::pair < int, int > new_coord;
120 switch (direction) {
121 case 0:
122 // Add move 'N'.
123 new_coord = std::make_pair(
124 active_paths_top_back.first,
125 active_paths_top_back.second + 1);
126 break;
127 case 1:
128 // Add move 'E'.
129 new_coord = std::make_pair(
130 active_paths_top_back.first + 1,
131 active_paths_top_back.second);
132 break;
133 case 2:
134 // Add move 'S'.
135 new_coord = std::make_pair(
136 active_paths_top_back.first,
137 active_paths_top_back.second - 1);
138 break;
139 case 3:
140 // Add move 'W'.
141 new_coord = std::make_pair(
142 active_paths_top_back.first - 1,
143 active_paths_top_back.second);
144 break;
145 }
146
147 // Push it to the queue of paths only if the movement
148 // makes sense.
149 new_move_back_x = new_coord.first;
150 new_move_back_y = new_coord.second;
151 if (new_move_back_x > -1 && new_move_back_x < map_width &&
152 new_move_back_y > -1 && new_move_back_y < map_height)
153 {
154 // Move is inside bounds.
155
156 // Check collision detection.
157 if (map[new_move_back_y * map_width + new_move_back_x])
158 {
159 // Check not visited.
160 if (! visited(
161 new_move_back_x,
162 new_move_back_y,
163 active_paths.top()))
164 {
165 move = active_paths_top;
166 move.reserve(out_buffer_size);
167 move.push_back(new_coord);
168 add_move.set_value(true);
169 }
170 }
171 }
172 }
它告诉我明确标记删除~__nat，我甚至不记得梦想做这样的事情。
我有点习惯于pthreads，Python线程，Java并行模型......不太了解不确定的选择，一般的异步，承诺......我应该努力让std::future使用吗？
答案 0 :(得分：2)
错误消息与新的C ++功能有关，“删除”默认操作符使其无法访问（以前，通常的技术是将它们设为私有）。
在您的情况下，它表示线程构造函数的参数存在问题。您的代码非常复杂，但您可能遇到过这个问题：C++ std::thread "Attempt to use a deleted function"
我当然会建议继续使用std：future。有关介绍，强烈建议Herb Sutter就新的C ++并发功能进行以下讨论：https://channel9.msdn.com/Shows/Going+Deep/C-and-Beyond-2012-Herb-Sutter-Concurrency-and-Parallelism