C++ 多线程编程pthread的基本使用详解

int pthread_create (pthread_t *thread,pthread_attr_t *attr,void *(*start_routine)(void *),void *arg);

void pthread_exit (void *retval);

int pthread_cancel (pthread_t thread);

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#define NUM_THREADS    5
void *PrintHello(void *threadid)
{
    long tid;
    tid = (long) threadid;
    printf("Hello World! It's me, thread #%ld!\n", tid);
    pthread_exit(NULL);
}
int main(int argc, char *argv[])
{
    pthread_t threads[NUM_THREADS];
    int rc;
    long t;
    for (t = 0; t < NUM_THREADS; t++)
    {
        printf("In main: creating thread %ld\n", t);
        rc = pthread_create(&threads[t], NULL, PrintHello, (void *) t);
        if (rc)
        {
            printf("ERROR; return code from pthread_create() is %d\n", rc);
            exit(-1);
        }
    }
    /* Last thing that main() should do */
    pthread_exit(NULL);
}

gcc -Wall hello.c -lpthread -o hello
./hello

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#define NUM_THREADS    8
char *messages[NUM_THREADS];
struct thread_data
{
    int thread_id;
    int sum;
    char *message;
};
struct thread_data thread_data_array[NUM_THREADS];
void *PrintHello(void *threadarg)
{
    int taskid, sum;
    char *hello_msg;
    struct thread_data *my_data;
    sleep(1);
    my_data = (struct thread_data *) threadarg;
    taskid = my_data->thread_id;
    sum = my_data->sum;
    hello_msg = my_data->message;
    printf("Thread %d: %s  Sum=%d\n", taskid, hello_msg, sum);
    pthread_exit(NULL);
}
int main(int argc, char *argv[])
{
    pthread_t threads[NUM_THREADS];
    int *taskids[NUM_THREADS];
    int rc, t, sum;
    sum = 0;
    messages[0] = "English: Hello World!";
    messages[1] = "French: Bonjour, le monde!";
    messages[2] = "Spanish: Hola al mundo";
    messages[3] = "Klingon: Nuq neH!";
    messages[4] = "German: Guten Tag, Welt!";
    messages[5] = "Russian: Zdravstvytye, mir!";
    messages[6] = "Japan: Sekai e konnichiwa!";
    messages[7] = "Latin: Orbis, te saluto!";
    for (t = 0; t < NUM_THREADS; t++)
    {
        sum = sum + t;
        thread_data_array[t].thread_id = t;
        thread_data_array[t].sum = sum;
        thread_data_array[t].message = messages[t];
        printf("Creating thread %d\n", t);
        rc = pthread_create(&threads[t], NULL, PrintHello, (void *)
                &thread_data_array[t]);
        if (rc)
        {
            printf("ERROR; return code from pthread_create() is %d\n", rc);
            exit(-1);
        }
    }
    pthread_exit(NULL);
}

int pthread_join(pthread_t threadid, void **value_ptr);

pthread_detach (threadid)
pthread_attr_setdetachstate (attr,detachstate)
pthread_attr_getdetachstate (attr,detachstate)

#include<stdlib.h>
#include <pthread.h>
#include <stdio.h>
#include <math.h>
#define NUM_THREADS 4
void *BusyWork(void *t)
{
    int i;
    long tid;
    double result = 0.0;
    tid = (long) t;
    printf("Thread %ld starting...\n", tid);
    for (i = 0; i < 1000000; i++)
    {
        result = result + sin(i) * tan(i);
    }
    printf("Thread %ld done. Result = %e\n", tid, result);
    pthread_exit((void *) t);
}
int main(int argc, char *argv[])
{
    pthread_t thread[NUM_THREADS];
    pthread_attr_t attr;
    int rc;
    long t;
    void *status;
/* Initialize and set thread detached attribute */
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    for (t = 0; t < NUM_THREADS; t++)
    {
        printf("Main: creating thread %ld\n", t);
        rc = pthread_create(&thread[t], &attr, BusyWork, (void *) t);
        if (rc)
        {
            printf("ERROR; return code from pthread_create() is %d\n", rc);
            exit(-1);
        }
    }
/* Free attribute and wait for the other threads */
    pthread_attr_destroy(&attr);
    for (t = 0; t < NUM_THREADS; t++)
    {
        rc = pthread_join(thread[t], &status);
        if (rc)
        {
            printf("ERROR; return code from pthread_join() is %d\n", rc);
            exit(-1);
        }
        printf("Main: completed join with thread %ld having a status of %ld\n", t, (long) status);
    }
    printf("Main: program completed. Exiting.\n");
    pthread_exit(NULL);
}

pthread_attr_getstacksize (attr, stacksize)
pthread_attr_setstacksize (attr, stacksize)
pthread_attr_getstackaddr (attr, stackaddr)
pthread_attr_setstackaddr (attr, stackaddr)

#include<stdlib.h>
#include <pthread.h>
#include <stdio.h>
#define NTHREADS 4
#define N 1000
#define MEGEXTRA 1000000
pthread_attr_t attr;
void *dowork(void *threadid)
{
    double A[N][N];
    int i, j;
    long tid;
    size_t mystacksize;
    tid = (long) threadid;
    pthread_attr_getstacksize(&attr, &mystacksize);
    printf("Thread %ld: stack size = %li bytes \n", tid, mystacksize);
    for (i = 0; i < N; i++)
        for (j = 0; j < N; j++)
            A[i][j] = ((i * j) / 3.452) + (N - i);
    pthread_exit(NULL);
}
int main(int argc, char *argv[])
{
    pthread_t threads[NTHREADS];
    size_t stacksize;
    int rc;
    long t;
    pthread_attr_init(&attr);
    pthread_attr_getstacksize(&attr, &stacksize);
    printf("Default stack size = %li\n", stacksize);
    stacksize = sizeof(double) * N * N + MEGEXTRA;
    printf("Amount of stack needed per thread = %li\n", stacksize);
    pthread_attr_setstacksize(&attr, stacksize);
    printf("Creating threads with stack size = %li bytes\n", stacksize);
    for (t = 0; t < NTHREADS; t++)
    {
        rc = pthread_create(&threads[t], &attr, dowork, (void *) t);
        if (rc)
        {
            printf("ERROR; return code from pthread_create() is %d\n", rc);
            exit(-1);
        }
    }
    printf("Created %ld threads.\n", t);
    pthread_exit(NULL);
}

pthread_self ();
pthread_equal (thread1,thread2);

pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER;

pthread_mutex_init (mutex,attr);
pthread_mutex_destroy (pthread_mutex_t *mutex);
pthread_mutexattr_init (attr);
pthread_mutexattr_destroy (attr);
phtread_mutex_lock(pthread_mutex_t *mutex);
phtread_mutex_trylock(pthread_mutex_t *mutex);
phtread_mutex_unlock(pthread_mutex_t *mutex);

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
/*   
The following structure contains the necessary information  
to allow the function "dotprod" to access its input data and 
place its output into the structure.  This structure is 
unchanged from the sequential version.
*/
typedef struct
{
    double *a;
    double *b;
    double sum;
    int veclen;
} DOTDATA;
/* Define globally accessible variables and a mutex */
#define NUMTHRDS 4
#define VECLEN 100000
DOTDATA dotstr;
pthread_t callThd[NUMTHRDS];
pthread_mutex_t mutexsum;
/*
The function dotprod is activated when the thread is created.
As before, all input to this routine is obtained from a structure 
of type DOTDATA and all output from this function is written into
this structure. The benefit of this approach is apparent for the 
multi-threaded program: when a thread is created we pass a single
argument to the activated function - typically this argument
is a thread number. All  the other information required by the 
function is accessed from the globally accessible structure. 
*/
void *dotprod(void *arg)
{
/* Define and use local variables for convenience */
    int i, start, end, len;
    long offset;
    double mysum, *x, *y;
    offset = (long) arg;
    len = dotstr.veclen;
    start = offset * len;
    end = start + len;
    x = dotstr.a;
    y = dotstr.b;
/*
Perform the dot product and assign result
to the appropriate variable in the structure. 
*/
    mysum = 0;
    for (i = start; i < end; i++)
    {
        mysum += (x[i] * y[i]);
    }
/*
Lock a mutex prior to updating the value in the shared
structure, and unlock it upon updating.
*/
    pthread_mutex_lock(&mutexsum);
    dotstr.sum += mysum;
    printf("Thread %ld did %d to %d: mysum=%f global sum=%f\n", offset, start,
           end, mysum, dotstr.sum);
    pthread_mutex_unlock(&mutexsum);
    pthread_exit((void *) 0);
}
/* 
The main program creates threads which do all the work and then print out result 
upon completion. Before creating the threads, The input data is created. Since 
all threads update a shared structure, we need a mutex for mutual exclusion. 
The main thread needs to wait for all threads to complete, it waits for each one 
of the threads. We specify a thread attribute value that allow the main thread to
join with the threads it creates. Note also that we free up handles  when they
are no longer needed.
*/
int main(int argc, char *argv[])
{
    long i;
    double *a, *b;
    void *status;
    pthread_attr_t attr;
/* Assign storage and initialize values */
    a = (double *) malloc(NUMTHRDS * VECLEN * sizeof(double));
    b = (double *) malloc(NUMTHRDS * VECLEN * sizeof(double));
    for (i = 0; i < VECLEN * NUMTHRDS; i++)
    {
        a[i] = 1;
        b[i] = a[i];
    }
    dotstr.veclen = VECLEN;
    dotstr.a = a;
    dotstr.b = b;
    dotstr.sum = 0;
    pthread_mutex_init(&mutexsum, NULL);
/* Create threads to perform the dotproduct  */
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    for (i = 0; i < NUMTHRDS; i++)
    {
        /* Each thread works on a different set of data.
         * The offset is specified by 'i'. The size of
         * the data for each thread is indicated by VECLEN.
         */
        pthread_create(&callThd[i], &attr, dotprod, (void *) i);
    }
    pthread_attr_destroy(&attr);
/* Wait on the other threads */
    for (i = 0; i < NUMTHRDS; i++)
    {
        pthread_join(callThd[i], &status);
    }
/* After joining, print out the results and cleanup */
    printf("Sum =  %f \n", dotstr.sum);
    free(a);
    free(b);
    pthread_mutex_destroy(&mutexsum);
    pthread_exit(NULL);
}

pthread_cond_t myconvar = PTHREAD_COND_INITIALIZER;

pthread_cond_wait (condition,mutex);
pthread_cond_signal (condition);
pthread_cond_broadcast (condition);

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#define NUM_THREADS  3
#define TCOUNT 10
#define COUNT_LIMIT 12
int count = 0;
pthread_mutex_t count_mutex;
pthread_cond_t count_threshold_cv;
void *inc_count(void *t)
{
    int i;
    long my_id = (long) t;
    for (i = 0; i < TCOUNT; i++)
    {
        pthread_mutex_lock(&count_mutex);
        count++;
        /* 
        Check the value of count and signal waiting thread when condition is
        reached.  Note that this occurs while mutex is locked. 
        */
        if (count == COUNT_LIMIT)
        {
            printf("inc_count(): thread %ld, count = %d  Threshold reached. ",
                   my_id, count);
            pthread_cond_signal(&count_threshold_cv);
            printf("Just sent signal.\n");
        }
        printf("inc_count(): thread %ld, count = %d, unlocking mutex\n",
               my_id, count);
        pthread_mutex_unlock(&count_mutex);
        /* Do some work so threads can alternate on mutex lock */
        sleep(1);
    }
    pthread_exit(NULL);
}
void *watch_count(void *t)
{
    long my_id = (long) t;
    printf("Starting watch_count(): thread %ld\n", my_id);
    /*
    Lock mutex and wait for signal.  Note that the pthread_cond_wait routine
    will automatically and atomically unlock mutex while it waits. 
    Also, note that if COUNT_LIMIT is reached before this routine is run by
    the waiting thread, the loop will be skipped to prevent pthread_cond_wait
    from never returning.
    */
    pthread_mutex_lock(&count_mutex);
    while (count < COUNT_LIMIT)
    {
        printf("watch_count(): thread %ld Count= %d. Going into wait...\n", my_id, count);
        pthread_cond_wait(&count_threshold_cv, &count_mutex);
        printf("watch_count(): thread %ld Condition signal received. Count= %d\n", my_id,
               count);
        printf("watch_count(): thread %ld Updating the value of count...\n", my_id, count);
        count += 125;
        printf("watch_count(): thread %ld count now = %d.\n", my_id, count);
    }
    printf("watch_count(): thread %ld Unlocking mutex.\n", my_id);
    pthread_mutex_unlock(&count_mutex);
    pthread_exit(NULL);
}
int main(int argc, char *argv[])
{
    int i, rc;
    long t1 = 1, t2 = 2, t3 = 3;
    pthread_t threads[3];
    pthread_attr_t attr;
    /* Initialize mutex and condition variable objects */
    pthread_mutex_init(&count_mutex, NULL);
    pthread_cond_init(&count_threshold_cv, NULL);
    /* For portability, explicitly create threads in a joinable state */
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    pthread_create(&threads[0], &attr, watch_count, (void *) t1);
    pthread_create(&threads[1], &attr, inc_count, (void *) t2);
    pthread_create(&threads[2], &attr, inc_count, (void *) t3);
    /* Wait for all threads to complete */
    for (i = 0; i < NUM_THREADS; i++)
    {
        pthread_join(threads[i], NULL);
    }
    printf("Main(): Waited and joined with %d threads. Final value of count = %d. Done.\n",
           NUM_THREADS, count);
    /* Clean up and exit */
    pthread_attr_destroy(&attr);
    pthread_mutex_destroy(&count_mutex);
    pthread_cond_destroy(&count_threshold_cv);
    pthread_exit(NULL);
}