C程序中的多线程TCP服务器

我用C写了一个多线程的TCP服务器，当我运行多个测试客户端时，它崩溃了。我得到两种类似的崩溃，这两种崩溃似乎都有相同的根本原因。附加的崩溃发生在main中。在另一种情况下，当客户端想要锁定以关闭套接字时，会发生崩溃。有人可以告诉我是什么原因导致了崩溃？C程序中的多线程TCP服务器

TCP服务器代码：

#include <stdio.h> 
#include <stdint.h> 
#include <stdlib.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <unistd.h> 
#include <arpa/inet.h> //inet_addr 
#include <pthread.h> //for threading , link with lpthread 

#define BUFSIZE  2048 // TODO 
#define MAXWORKERS 10 

pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER; 
const pthread_cond_t condInit = PTHREAD_COND_INITIALIZER; 
pthread_cond_t idle = PTHREAD_COND_INITIALIZER; 

typedef struct { 
    pthread_t  tid; 
    int    sd; 
    pthread_cond_t cond; 
    uint8_t   num; 
    uint8_t   state; 
} worker_t; 

worker_t  workers[MAXWORKERS]; // reference to worker 

void error(const char *msg) 
{ 
    perror(msg); 
    exit(1); 
} 

/* worker thread */ 
void *handle_client(void *arg) 
{ 
    worker_t* worker = (worker_t *) arg; 
    int n; 
    char buf[BUFSIZE]; 

    /* By default a new thread is joinable, we don't 
    really want this (unless we do something special we 
    end up with the thread equivalent of zombies). So 
    we explicitly change the thread type to detached 
    */ 

    pthread_detach(pthread_self()); 

    printf("Thread %ld started for client number %d (sd %d)\n", pthread_self(), 
      worker->num, worker->sd); 

    /* worker thread */ 
    while (1) 
    { 
     /* wait for work to do */ 
     while (worker->state == 0) 
     { 
      pthread_cond_wait(&worker->cond, &mtx); 
     } 
     int sd = worker->sd; /* get the updated socket fd */ 
     pthread_mutex_unlock(&mtx); 

     n = read(sd, buf, BUFSIZE); 
     if (n < 0) 
      error("ERROR reading from socket"); 

     n = write(sd, "I got your message",18); 
     if (n < 0) 
      error("ERROR writing to socket"); 

     /* work done - set itself idle assumes that read returned EOF */ 
     pthread_mutex_lock(&mtx); 
     close(sd); 
     worker->state = 0; 
     printf("Worker %d has completed work \n", worker->num); 
     pthread_cond_signal(&idle); /* notifies dispatcher*/ 
     pthread_mutex_unlock(&mtx); 
    } /* end while */ 

} 

int main() { /* Dispatcher */ 
    int ld, sd; 
    struct sockaddr_in skaddr; 
    struct sockaddr_in from; 
    int addrlen, length; 
    int i; 

    if ((ld = socket(AF_INET, SOCK_STREAM, 0)) < 0) { 
     perror("Problem creating socket\n"); 
     exit(1); 
    } 

    skaddr.sin_family = AF_INET; 
    skaddr.sin_addr.s_addr = htonl(INADDR_ANY); 

    //skaddr.sin_port = htons(0); 
    skaddr.sin_port = htons(41332); 

    if (bind(ld, (struct sockaddr *) &skaddr, sizeof(skaddr)) < 0) { 
     perror("Problem binding\n"); 
     exit(0); 
    } 

    /* find out what port we were assigned and print it out */ 

    length = sizeof(skaddr); 
    if (getsockname(ld, (struct sockaddr *) &skaddr, &length) < 0) { 
     perror("Error getsockname\n"); 
     exit(1); 
    } 
    in_port_t pport = ntohs(skaddr.sin_port); 
    printf("%d\n", pport); 

    /* put the socket into passive mode (waiting for connections) */ 

    if (listen(ld, 5) < 0) { 
     perror("Error calling listen\n"); 
     exit(1); 
    } 

    /* do some initialization */ 

    for (i = 0; i < MAXWORKERS; i++) { 
     workers[i].state = 0; 
     workers[i].num  = i; 
     workers[i].sd  = 0; 
     workers[i].cond  = condInit; 
     pthread_create(&workers[i].tid, NULL, handle_client, (void *) &workers[i]); 
    } 

    /* Dispatcher now processes incoming connections forever ... */ 
    while (1) { 
     printf("Ready for a connection...\n"); 
     addrlen = sizeof(skaddr); 

     printf("trying to accept a new connection\n"); 
     if ((sd = accept(ld, (struct sockaddr*) &from, &addrlen)) < 0) { 
      perror("Problem with accept call\n"); 
      exit(1); 
     } 
     printf("Got a connection - processing...\n"); 
     for (i = 0; i < MAXWORKERS; i++) { 
      pthread_mutex_lock(&mtx); 
      if (workers[i].state == 0) /* worker i is idle – dispatch him to work */ 
      { 
       printf("dispatch to worker number: %d \n", i); 
       pthread_mutex_unlock(&mtx); 
       break; 
      } 
      printf("worker number: %d was busy\n", i); 

      pthread_mutex_unlock(&mtx); 
     } 

     if (i == MAXWORKERS) { 
      /* all workers busy */ 
      pthread_mutex_lock(&mtx); 
      pthread_cond_wait(&idle, &mtx); /* wait for one idle; */ 
      pthread_mutex_unlock(&mtx); 
     } else { /* dispatch worker */ 
      pthread_mutex_lock(&mtx); 
      workers[i].state = 1; 
      workers[i].sd = sd; 
      pthread_cond_signal(&workers[i].cond); /* wake up worker */ 
      pthread_mutex_unlock(&mtx); 
     } 
    } 
}

崩溃：

Thread 11 (Thread 0x7fae90004700 (LWP 16318)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x602408 <workers+648>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae90004700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 10 (Thread 0x7fae90805700 (LWP 16317)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x6023c0 <workers+576>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae90805700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 9 (Thread 0x7fae9400c700 (LWP 16310)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x6021c8 <workers+72>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae9400c700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 8 (Thread 0x7fae91006700 (LWP 16316)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x602378 <workers+504>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae91006700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 7 (Thread 0x7fae91807700 (LWP 16315)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x602330 <workers+432>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae91807700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 6 (Thread 0x7fae9300a700 (LWP 16312)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x602258 <workers+216>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae9300a700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 5 (Thread 0x7fae92008700 (LWP 16314)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x6022e8 <workers+360>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae92008700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 4 (Thread 0x7fae92809700 (LWP 16313)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x6022a0 <workers+288>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae92809700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 3 (Thread 0x7fae9380b700 (LWP 16311)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x602210 <workers+144>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae9380b700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 2 (Thread 0x7fae9480d700 (LWP 16309)): 
#0 [email protected]@GLIBC_2.3.2() at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 
#1 0x0000000000401024 in handle_client (arg=0x602180 <workers>) at main.c:87 
#2 0x00007fae94bdf6ba in start_thread (arg=0x7fae9480d700) at pthread_create.c:333 
#3 0x00007fae949153dd in clone() at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 

Thread 1 (Thread 0x7fae94ff3700 (LWP 16308)): 
#0 0x00007fae94843428 in __GI_raise ([email protected]=6) at ../sysdeps/unix/sysv/linux/raise.c:54 
---Type <return> to continue, or q <return> to quit--- 
#1 0x00007fae9484502a in __GI_abort() at abort.c:89 
#2 0x00007fae9483bbd7 in __assert_fail_base (fmt=<optimized out>, [email protected]=0x7fae94beb015 "mutex->__data.__owner == 0", [email protected]=0x7fae94beaff8 "../nptl/pthread_mutex_lock.c", [email protected]=81, 
    [email protected]=0x7fae94beb180 <__PRETTY_FUNCTION__.8623> "__pthread_mutex_lock") at assert.c:92 
#3 0x00007fae9483bc82 in __GI___assert_fail ([email protected]=0x7fae94beb015 "mutex->__data.__owner == 0", [email protected]=0x7fae94beaff8 "../nptl/pthread_mutex_lock.c", [email protected]=81, 
    [email protected]=0x7fae94beb180 <__PRETTY_FUNCTION__.8623> "__pthread_mutex_lock") at assert.c:101 
#4 0x00007fae94be1f68 in __GI___pthread_mutex_lock ([email protected]=0x602140 <mtx>) at ../nptl/pthread_mutex_lock.c:81 
#5 0x0000000000400cfa in main() at main.c:173

来源

2017-07-11 Mass

尝试。 – dbush

你必须**在调用'pthread_cond_wait'前先锁定'mutex'。 – BetaRunner

@BetaRunner [商定]（https://stackoverflow.com/questions/16522858/understanding-of-pthread-cond-wait-and-pthread-cond-signal） – jeff6times7

在你的工作线程，这种情况发生的第一件事要么是pthread_cond_wait，而无需先锁定互斥体或pthread_mutex_unlock，而无需先锁定了互斥体。在这两种情况下，根据POSIX文档，这都是未定义的行为。

你的工人函数应该这样开始：在[的valgrind（http://valgrind.org）运行

/* worker thread */ 
while (1) 
{ 
    /* wait for work to do */ 
    pthread_mutex_lock(&mtx); 
    while (worker->state == 0) 
    { 
     pthread_cond_wait(&worker->cond, &mtx); 
    } 
    int sd = worker->sd; /* get the updated socket fd */ 
    pthread_mutex_unlock(&mtx);

来源

2017-07-11 13:45:05 JeremyP

C程序中的多线程TCP服务器

回答

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