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Full Discussion: Thread parameter in ANSI C makes a segmentation fault
Top Forums Programming Thread parameter in ANSI C makes a segmentation fault Post 302520421 by sehang on Sunday 8th of May 2011 02:21:37 AM
Old 05-08-2011
Finally, I found the problem, it is caused by use of select().
And the error message is "too many open file descriptors"; Besides, I used "netstat -an" to check the network status, I saw a lot of ESTABLISHED connections and can't release.
But I always use a close() after the descriptor completed. Why this problem happens in my program?


I post the source code of client and server side.
Client.c
Code:
  int Close ( int fd, const char* filename, int line ) {
      int ret;
      if ( ( ret = close( fd ) ) == -1 ) {
  #ifdef LOGGING_ENABLE
          sprintf( log, "%s(%d) -> close() failed: %s", filename, line, strerror( errno ) );
          Log( log );
  #endif
      }
      return ret;
  }
  
  void Client_CloseConnection ( int sockfd ) {
      Close( sockfd, __FILE__, __LINE__ );
  }
  
static void* CLIENT_THREAD ( void* v ) {
    int sockfd;                                 /* Socket descriptor. */
    int index = *( int* )v; /*free( v );*/          /* Position in the @PeerList. */
    ...

    /* Assume the connection is OK by default. */
    Pthread_rwlock_wrlock( &rwlock, __FILE__, __LINE__ );
    node->state = CONNECTED;
    Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );

    while ( 1 ) {
        /* Wait until messages come. */
        Pthread_mutex_lock( &node->mutex, __FILE__, __LINE__ );
        Pthread_rwlock_rdlock( &rwlock, __FILE__, __LINE__ );
        tmp = Queue4SendData_GetCount( & ( node->Q ) );
        Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );
        while ( tmp == 0 ) {
            Pthread_cond_wait( &node->isEmpty, &node->mutex, __FILE__, __LINE__ );
            Pthread_rwlock_rdlock( &rwlock, __FILE__, __LINE__ );
            tmp = Queue4SendData_GetCount( & ( node->Q ) );
            Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );
            if ( tmp == 0 )
                continue;
            break;
        }

        //Get the message which going to send
        Pthread_rwlock_wrlock( &rwlock, __FILE__, __LINE__ );
        data = Queue4SendData_Pop( & ( node->Q ) );
        Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );

        /* Let Producer continue insert items. */
        Pthread_cond_signal( &node->isFull, __FILE__, __LINE__ );
        Pthread_mutex_unlock( &node->mutex, __FILE__, __LINE__ );

        tmp = 1;        /* Status flag (0 = error, 1 = OK). */
        if ( Client_TestConnection( &sockfd, IPStr ) ) {
            Writen( sockfd, data.send_buf, strlen( data.send_buf ), __FILE__, __LINE__ );
            if ( ( n = Readline( index, sockfd, recvline, TCP_MAXLINE ) ) <= 0 ) {
#ifdef LOGGING_ENABLE
                if ( n == 0 )
                    sprintf( log, "%s(%d) -> Server %s terminated prematurely", __FILE__, __LINE__, IPStr );
                else
                    sprintf( log, "%s(%d) -> Readline() on %s failed: %s", __FILE__, __LINE__, IPStr, strerror( errno ) );
                Log( log );
#endif
                tmp = 0;
            } else {
                handler = data.handler;
                handler( recvline, IPStr );     /* Call packet handler. */
            }
        } else {
            tmp = 0;
        }

        //DON'T FORGET THESE CODES.
        Client_CloseConnection( sockfd ); <- close is called here!!
        if ( tmp == 0 )
            break;
    }
    return NULL;
}

This function used to create a connection with a server; in my project, a client needs to connect few servers at the same time.
void Client_Constructor ( const char* IPAddr ) {
    int status;
    pthread_t tid;      /* Thread ID. */
    pthread_attr_t rx;  /* Parameter of thread. */
    int pos = Client_GetPosition( IPAddr );
    struct PeerInfo* node = &PeerList[ pos ];
    
    Pthread_rwlock_rdlock( &rwlock, __FILE__, __LINE__ );
    status = node->state;
    Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );
    
    if ( status == DISCONNECTED ) {   //Server is offline, then connect it!
        Pthread_rwlock_wrlock( &rwlock, __FILE__, __LINE__ );
        strcpy( node->IPStr, IPAddr ); 
        Queue4SendData_Init( &( node->Q ), SEND_QUEUE );
        node->state = CONNECTING;                       
        Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );
        Pthread_attr_init( &rx, __FILE__, __LINE__ ); 
        Pthread_attr_setdetachstate( &rx, PTHREAD_CREATE_DETACHED, __FILE__, __LINE__ );

        Pthread_rwlock_wrlock( &tbRwlock, __FILE__, __LINE__ );
        if ( threadBufPos >= 1024 )
            threadBufPos = 0;
        threadBuf[ threadBufPos ] = pos;
        Pthread_create( &tid, &rx, CLIENT_THREAD, ( void* )&( threadBuf[ threadBufPos ] ), __FILE__, __LINE__ );
        threadBufPos++;
        Pthread_rwlock_unlock( &tbRwlock, __FILE__, __LINE__ );
    }
}

Send messages to a server, IPAddr is the IP address of server.
void Client_Pend ( const char* IPAddr, struct SendDataStruct *data ) {
    struct SendDataStruct local;
    struct PeerInfo* node = &PeerList[ Client_GetPosition( IPAddr ) ];
    enum TCPState TCPStatus;
    int qSize;
    Pthread_rwlock_rdlock( &rwlock, __FILE__, __LINE__ );
    TCPStatus = node->state;                        /* Recent TCP status of the connection. */
    Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );
    
    if ( TCPStatus == CONNECTED ) {
        /* Blocking if the queue is full. */
        Pthread_mutex_lock( &node->mutex, __FILE__, __LINE__ );
        Pthread_rwlock_rdlock( &rwlock, __FILE__, __LINE__ );
        qSize = Queue4SendData_GetCount( & ( node->Q ) );
        Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );
        while ( SEND_QUEUE <= qSize ) {
            Pthread_cond_wait( &node->isFull, &node->mutex, __FILE__, __LINE__ );
            Pthread_rwlock_rdlock( &rwlock, __FILE__, __LINE__ );
            qSize = Queue4SendData_GetCount( & ( node->Q ) );
            Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );
            if ( SEND_QUEUE <= qSize )
                continue;   /* If the Queue is full, then blocking. */
            break;
        }

        Pthread_rwlock_wrlock( &rwlock, __FILE__, __LINE__ );
        local.handler = data->handler;             /* Clone packet handler. */
        strcpy( local.send_buf, data->send_buf );  /* Clone message to temporary array. */
        if ( Queue4SendData_Insert( & ( node->Q ), local ) == -1 ) {
#ifdef LOGGING_ENABLE
            sprintf( log, "%s(%d) -> Queue is full on client %s", __FILE__, __LINE__, node->IPStr );
            Log( log );
#endif
            exit( -1 );
        } else {
        }
        Pthread_rwlock_unlock( &rwlock, __FILE__, __LINE__ );

        /* Let the consumer read the inserted item. */
        Pthread_cond_signal( &node->isEmpty, __FILE__, __LINE__ );
        Pthread_mutex_unlock( &node->mutex, __FILE__, __LINE__ );
    } else if ( TCPStatus == DISCONNECTED ) {
        Client_Constructor( node->IPStr );
    }
}

Server.c
Code:
void Server_Constructor () {
    ssize_t n;
    int i, maxi, maxfd, listenfd, connfd, sockfd;
    int nready, client[ FD_SETSIZE ];
    fd_set rset, allset;
    char buf[ TCP_MAXLINE ];
    struct sockaddr_in cliaddr, srvAddr;
    socklen_t clilen;
    TIMER t = 0;

    if ( ( listenfd = Socket( AF_INET, SOCK_STREAM, 0, __FILE__, __LINE__ ) ) == -1 )
        return; /* Fail to create a socket. */
    i = 1;
    Setsockopt( listenfd, SOL_SOCKET, SO_REUSEADDR, &i, sizeof( int ), __FILE__, __LINE__ );    /* Reuse the socket. */

    /* Initiate server's address. */
    bzero( &srvAddr, sizeof( srvAddr ) );
    srvAddr.sin_family      = AF_INET;
    srvAddr.sin_addr.s_addr = htonl( INADDR_ANY );
    srvAddr.sin_port        = htons( TCP_PORT );

    if ( Bind( listenfd, ( struct sockaddr* )&srvAddr, sizeof( srvAddr ), __FILE__, __LINE__ ) == -1 )
        return; /* Fail to bind the socket. */
    if ( Listen( listenfd, TCP_MAX_PENGING, __FILE__, __LINE__ ) == -1 )
        return; /* Fail to listen to the socket. */

    /* Initiate select. */
    maxfd = listenfd;   /* Initialize. */
    maxi  = -1;         /* Index into client[] array. */
    for ( i = 0; i < FD_SETSIZE; client[ i ] = -1, i++ );   /* -1 indicates available entry. */
    FD_ZERO( &allset );
    FD_SET( listenfd, &allset );

    for ( ; ; ) {
        t = time2MS();
        rset = allset;      /* Structure assignment. */
        nready = Select( maxfd + 1, &rset, NULL, NULL, NULL, __FILE__, __LINE__ );
        if ( FD_ISSET( listenfd, &rset ) ) {    /* New client connection. */
            clilen = sizeof( cliaddr );
            if ( ( connfd = Accept( listenfd, ( struct sockaddr* )&cliaddr, &clilen, __FILE__, __LINE__ ) ) == -1 )
                continue;


            for ( i = 0; i < FD_SETSIZE ; i++ )
                if ( client[ i ] < 0 ) {
                    client[ i ] = connfd; /* save descriptor. */
                    break;
                }

            if ( i == FD_SETSIZE ) {
#ifdef LOGGING_ENABLE
                sprintf( buf, "%s(%d) -> Too many clients", __FILE__, __LINE__ );
                Log( buf );
#endif
                return;
            }

            FD_SET( connfd, &allset );              /* Add new descriptor to set. */
            if ( connfd > maxfd ) maxfd = connfd;   /* For select. */
            if ( i > maxi ) maxi = i;               /* Max index in client[] array. */
            if ( --nready <= 0 ) continue;          /* No more readable descriptors. */
        }

        /* Check all clients for data. */
        for ( i = 0; i <= maxi ; i++ ) {
            if ( ( sockfd = client[ i ] ) < 0 )
                continue;
            if ( FD_ISSET( sockfd, &rset ) ) {
                if ( readable_timeo( sockfd, 1 ) <= 0 ) {
                    printf( "UNABLE TO READ %d\n", sockfd );
                    exit( -1 );
                } else if ( ( n = Readline( sockfd, buf, TCP_MAXLINE ) ) <= 0 ) {  /* For connection closed by client. */
                    Close( sockfd, __FILE__, __LINE__ ); <- close is called here!!
                    FD_CLR( sockfd, &allset );
                    client[ i ] = -1;
                } else {
                    PacketHandler( sockfd, buf, n );
                }
                if ( --nready <= 0 )  break;    /* No more readable descriptors. */
            }
        }
    }
}

Errors
Code:
Server.c(271) -> accept() failed: Too many open files
...
/Client.c(332) -> close() failed: Bad file descriptor
...

Last edited by sehang; 05-08-2011 at 03:31 AM..
 

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