C - socketserver：pthread_create - 无法创建线程 errno 12

Question

I create Threads in a C Program for every incoming Client connection. While Stress Testing with 400 parallel connections i got error 12 from pthread_create. I know that this can happen when running out of ressources, but should not be the case whith that few connections.. so why is that?

 #define MAX_CONNECTIONS 1000

pthread_t tid[MAX_CONNECTIONS];
        int i = 0;


        while(1) {

                        //Accept call creates a new socket for the incoming connection
                         addr_size = sizeof serverStorage;

                         // allocate socketfd on the heap to avoid nasty race conditions
                         int * socketfd;
                         socketfd = malloc(sizeof(int));

                         *socketfd = accept(listenfd, (struct sockaddr *) &serverStorage, &addr_size);

                        //create a thread for each client request and assign the client request to it for processing
                        //the main thread can now serve the next request
                        int err = pthread_create(&tid[i], NULL, socketThread, socketfd);
                        if(err) {
                                slog_error(0,"Failed to create thread %d",err);
                                exit(3);
                        }

                        if( i >= MAX_CONNECTIONS)
                        {
                                i = 0;
                                while( i < MAX_CONNECTIONS )
                                {
                                        pthread_join(tid[i++],NULL);
                                }
                                i = 0;
                        }


 

popen part of the thread

 
                   if(injector) {
                        DEBUG slog_debug(0, "injector reached");
                        DEBUG slog_debug(0,"Starting injector helper %s",injector_command);
                        errno = 0;
                        if ( (pop = popen(injector_command, "w") ) == NULL ) {
                        slog_error(0,"popen injector FAILED continue without injection %d",errno);
                        pop = 0;
                        }
                        if (pop) {
                                DEBUG slog_debug(0, "print to injector reached");
                                if( (bytes = fwrite(nm_data,1,strlen(nm_data),pop)) != strlen(nm_data)) {
                                        slog_error(0,"Failed to write to injector %s,%s,%d",hostname,bytes,errno);
                                        pop = (FILE *)0; /* stop writing */
                                        exit(1);
                                }
                        }
                        fflush(pop);
                        pclose(pop);

                    }
                    

Answer 1

pthread_create(&tid[i], NULL, socketThread, &socketfd) creates a nasty race condition. You're going to have real problems if another call to accept() returns before the thread you created dereferences the address to get its socket. see update code in initial question.