Question

I have create a pthread_create inside a pthread_create, I have used socket programming, where I receive a packet and then create a thread which does the writing to the file. When I send a very large file, i get this error…??

The code is as follows…

void *writePack(void *sock)
{

    size_t nbyte;
    ssize_t writeSize;
    nbyte = 1466;
    off_t offset;
    offset = (((struct writePacket *)sock)->seq * 1466);
    char* buffer = new char();
    buffer = ((struct writePacket *)sock)->datamsg;
    writeSize = pwrite(((struct writePacket *)sock)->pp,(const void *)buffer, nbyte, offset );
    free(buffer);
    pthread_exit(NULL);
}

this is the code of the parent receive code…

recvfrom(sockA->sockid, (void *)&recvdata, sizeof(struct data), 0, (struct sockaddr *) &cli_addr, &clilen);
        if (n<0)
            error("Error on reading");

        pthread_mutex_lock(&qlock);
                struct writePacket* a;
        a=new writePacket;
        a->sockID = sockA->sockid;
        a->pp = sockA->pp;
        a->seq = recvdata.seq;
        memcpy(a->datamsg,recvdata.datamsg,1466);

        pc = pthread_create(&write[counter], NULL, writePack,(void *) a);
                     if (pc)
                        {
                           printf("ERROR; return code from pthread_create() is %d\n", pc);
                             exit(-1);
                        }

Answer 1

It could be that the threads you create didn’t get a chance to execute, while you’ve been creating more and more threads reading from the socket.

Instead, create a thread that would do the reading from the socket, another thread that would do the writing, and pass the data in messages between the two threads.