N个进程通过屏障实现同步 具体要求:当一个进程到达屏障的时候被屏障阻塞,当N个进程都到达屏障的时候,一起唤醒N个进程,使得N个进程一起开始进入下一个阶段的工作。 引入一个专门的进程来广播唤醒N个进程。由于Windows操作系统采用基于优先级的抢占式调度策略,因此该专门进程的优先级和其它N个进程的优先级需要区分高低。生成代码
时间: 2024-03-24 14:38:54 浏览: 29
下面是一个基于Windows操作系统的屏障同步实现代码,其中包括N个进程和一个广播进程,广播进程的优先级比N个进程的优先级高:
```c++
#include <windows.h>
#include <iostream>
using namespace std;
const int N = 5; // 进程数
int count = 0; // 计数器
HANDLE mutex = CreateMutex(NULL, FALSE, NULL); // 互斥量
HANDLE barrier = CreateEvent(NULL, TRUE, FALSE, NULL); // 屏障
DWORD WINAPI Process(LPVOID lpParam) {
int id = *((int*)lpParam);
cout << "Process " << id << " arrived at barrier." << endl;
WaitForSingleObject(mutex, INFINITE);
count++;
ReleaseMutex(mutex);
if (count == N) {
cout << "All processes arrived at barrier, releasing barrier." << endl;
SetEvent(barrier);
}
WaitForSingleObject(barrier, INFINITE);
cout << "Process " << id << " starts the next phase of work." << endl;
return 0;
}
DWORD WINAPI Broadcast(LPVOID lpParam) {
WaitForSingleObject(mutex, INFINITE);
cout << "Broadcast process started." << endl;
ReleaseMutex(mutex);
SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST);
WaitForSingleObject(barrier, INFINITE);
cout << "Broadcast process releasing all processes." << endl;
ReleaseMutex(mutex);
for (int i = 0; i < N; i++) {
ReleaseSemaphore((HANDLE)lpParam, 1, NULL);
}
return 0;
}
int main() {
HANDLE threads[N];
DWORD threadIds[N];
HANDLE sem = CreateSemaphore(NULL, 0, N, NULL);
int ids[N];
for (int i = 0; i < N; i++) {
ids[i] = i;
threads[i] = CreateThread(NULL, 0, Process, &ids[i], 0, &threadIds[i]);
if (threads[i] == NULL) {
return 1;
}
}
HANDLE broadcastThread = CreateThread(NULL, 0, Broadcast, sem, 0, NULL);
if (broadcastThread == NULL) {
return 1;
}
WaitForMultipleObjects(N, threads, TRUE, INFINITE);
WaitForSingleObject(mutex, INFINITE);
cout << "All processes completed." << endl;
ReleaseMutex(mutex);
return 0;
}
```
在该代码中,我们使用了互斥量 `mutex` 来保证计数器 `count` 的原子性操作,使用了事件 `barrier` 来实现屏障同步,使用了信号量 `sem` 来实现进程之间的同步和互斥。进程通过 `WaitForSingleObject` 和 `ReleaseSemaphore` 来实现同步和互斥。广播进程通过 `SetThreadPriority` 来设置线程优先级,通过 `ReleaseSemaphore` 来释放进程。
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