线程

linux下通过pthread_create创建一个线程：

线程执行例程

函数原型：

void* start_routine(void *arg)
{
  void *name = (void *) (arg);
  printf("thread %s called.\n", name);
  return NULL;
}

int main()
{
  pthread_t pthread;
  pthread_create(&pthread, NULL, start_routine, "#1");
  return 0;
}

gcc pthread_create_test.c -o pthread_create_test -lpthread

linux下C程序主线程结束会终止其他线程的执行，也就是说不会等到其他线程结束之后才结束整个进程。

void* start_routine(void *arg)
{
  void *name = (void *) (arg);
  
  sleep(10); // sleep 10 seconds.
  
  printf("thread %s called.\n", name);
  return NULL;
}

int main()
{
  pthread_t pthread;
  pthread_create(&pthread, NULL, start_routine, "#1");
  return 0;
}

clean-up handlers & Thread-specific data destructors

相关函数

clean-up handlers:

void pthread_cleanup_push(void (*routine)(void *), void *arg);

void pthread_cleanup_pop(int execute);

void pthread_cleanup_handler(void *arg) 
{
	printf("pthread_cleanup_handler called.\n");
}

pthread_cleanup_push(pthread_cleanup_handler, NULL);

pthread_cleanup_pop(0);

例子：

调用pthread_exit函数终止线程时，clean-up handlers将全部弹出并被调用，调用顺序按照push顺序的反顺序。

如果有线程相关数据，在clean-up handlers调用后，对应的Thread-specific data destructors也将被调用，调用顺序未说明。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <errno.h>
#include <sys/types.h>
 
int *exitStatus = NULL;
void pthread_cleanup_handler(void *arg) 
{
	printf("pthread_cleanup_handler called.\n");
}

void* run_up(void *arg)
{
  pid_t pid = getpid();
  // pid_t tid = gettid(); // Glibc does not provide a wrapper for this system call; call it using syscall(2).
  pthread_t tid = pthread_self();
  printf("pid: %ld, tid: %ld\n", pid, tid);
  printf("&exitStatus: %d, exitStatus: %d, *exitStatus: %d, &*exitStatus: %d\n", &exitStatus, exitStatus, *exitStatus, &*exitStatus);

  pthread_cleanup_push(pthread_cleanup_handler, NULL);
 
  pthread_exit((void *) exitStatus);
 
  pthread_cleanup_pop(0);
  return (void *) exitStatus;
}
 
 
int main()
{
  exitStatus = (int *) malloc(sizeof(int));
  *exitStatus = 8;

  
 
  pthread_t pthread1, pthread2;
  int result = pthread_create(&pthread1, 
    NULL, 
    run_up, 
    (void *) 0);
  if (result)
  {
    printf("error: pthread_create, errno: %d\n", result);
  }
  printf("pthread: %ld\n", pthread1);

  
  int *p_status = (int *) malloc(sizeof(int));
  int **status = &p_status;
  result = pthread_join(pthread1, (void **) status);
  if (result) 
  {
    printf("error: pthread_join, errno: %d\n", result);
  }
  printf("&p_status: %d, p_status: %d, *p_status: %d, &*p_status: %d\n", &p_status, p_status, *p_status, &*p_status);
  printf("&status: %d, status: %d, *status: %d, &*status: %d, **status: %d, &**status: %d\n", &status, status, *status, &*status, **status, &**status);

  return 0;
}

Thread-specific data destructors:

int pthread_key_create(pthread_key_t *key, void (*destructor)(void*));