C程序中的多線程TCP服務器

我用C寫了一個多線程的TCP服務器，當我運行多個測試客戶端時，它崩潰了。我得到兩種類似的崩潰，這兩種崩潰似乎都有相同的根本原因。附加的崩潰發生在main中。在另一種情況下，當客戶端想要鎖定以關閉套接字時，會發生崩潰。有人可以告訴我是什麼原因導致了崩潰？C程序中的多線程TCP服務器

TCP服務器代碼：

#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); 
     } 
    } 
}

崩潰：

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

來源

2017-07-11 Mass

嘗試。 – dbush

你必須**在調用'pthread_cond_wait'前先鎖定'mutex'。 – BetaRunner

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

在你的工作線程，這種情況發生的第一件事要麼是pthread_cond_wait，而無需先鎖定互斥體或pthread_mutex_unlock，而無需先鎖定了互斥體。在這兩種情況下，根據POSIX文檔，這都是未定義的行爲。

你的工人函數應該這樣開始：在[的valgrind（http://valgrind.org）運行

/* 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);

來源

2017-07-11 13:45:05 JeremyP

C程序中的多線程TCP服務器

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