使用互斥量2进程之间的屏障同步
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我需要使用互斥锁（仅）在2个线程之间实现屏障同步。屏障同步是2个线程将在预定义的步骤互相等待，然后再继续。
我可以使用seamaphore来做到这一点，但是我如何仅使用互斥锁来做到这一点。提示我需要2个互斥锁而不是1个。
使用Seamaphore：
#include <pthread.h>
#include <semaphore.h>
using namespace std;
sem_t s1;
sem_t s2;
void* fun1(void* i)
{
cout << \"fun1 stage 1\" << endl;
cout << \"fun1 stage 2\" << endl;
cout << \"fun1 stage 3\" << endl;
sem_post (&s1);
sem_wait (&s2);
cout << \"fun1 stage 4\" << endl;
}
void* fun2(void* i)
{
cout << \"fun2 stage 1\" << endl;
cout << \"fun2 stage 2\" << endl;
// sleep(5);
sem_post (&s2);
sem_wait (&s1);
cout << \"fun2 stage 3\" << endl;
}
main()
{
sem_init(&s1, 0, 0);
sem_init(&s2, 0, 0);
int value;
sem_getvalue(&s2, &value);
cout << \"s2 = \" << value << endl;
pthread_t iThreadId;
cout << pthread_create(&iThreadId, NULL, &fun2, NULL) << endl;
// cout << pthread_create(&iThreadId, NULL, &fun2, NULL) << endl;
pthread_create(&iThreadId, NULL, &fun1, NULL);
sleep(10);
}
没有找到相关结果
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门锑腺潮
#include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <signal.h> static sigset_t _fSigSet; static volatile int _cMax=20, _cWait = 0; static pthread_t _aThread[1000]; void * thread(void *idIn) { int nSig, iThread, cWait, id = (int)idIn; printf(\"Start %d\\n\", id, cWait, _cMax); // do some fake weork nanosleep(&(struct timespec){0, 500000000}, NULL); // barrier cWait = __sync_add_and_fetch(&_cWait, 1); printf(\"Middle %d, %d/%d Waiting\\n\", id, cWait, _cMax); if (cWait < _cMax) { // if we are not the last thread, sleep on signal sigwait(&_fSigSet, &nSig); // sleepytime } else { // if we are the last thread, don\'t sleep and wake everyone else up for (iThread = 0; iThread < _cMax; ++iThread) if (iThread != id) pthread_kill(_aThread[iThread], SIGUSR1); } // watch em wake up cWait = __sync_add_and_fetch(&_cWait, -1); printf(\"End %d, %d/%d Active\\n\", id, cWait, _cMax); return 0; } int main(int argc, char** argv) { pthread_attr_t attr; int i, err; sigemptyset(&_fSigSet); sigaddset(&_fSigSet, SIGUSR1); sigaddset(&_fSigSet, SIGSEGV); printf(\"Start\\n\"); pthread_attr_init(&attr); if ((err = pthread_attr_setstacksize(&attr, 16384)) != 0) { printf(\"pthread_attr_setstacksize failed: err: %d %s\\n\", err, strerror(err)); exit(0); } for (i = 0; i < _cMax; i++) { if ((err = pthread_create(&_aThread[i], &attr, thread, (void*)i)) != 0) { printf(\"pthread_create failed on thread %d, error code: %d %s\\n\", i, err, strerror(err)); exit(0); } } for (i = 0; i < _cMax; ++i) pthread_join(_aThread[i], NULL); printf(\"\\nDone.\\n\"); return 0; }厘恼轨