Hello, I am working on incorporating async I/O in postgres. I had the foll. doubts in async operation. If I do for(i=0;i<MAX;i++){ bzero( (char *)&aiocb1[i], sizeof(struct aiocb) ); aiocb1[i].aio_fildes = fd; aiocb1[i].aio_nbytes = BUF_SIZE; aiocb1[i].aio_buf = malloc(BUF_SIZE+1); aiocb1[i].aio_offset = off+100; //next_offset; aiocb1[i].aio_lio_opcode = LIO_READ; sigemptyset(&sig_act[i].sa_mask); sig_act[i].sa_flags = SA_SIGINFO; sig_act[i].sa_sigaction = aio_completion_handler; aiocb1[i].aio_sigevent.sigev_notify = SIGEV_SIGNAL; aiocb1[i].aio_sigevent.sigev_signo = SIGIO; aiocb1[i].aio_sigevent.sigev_value.sival_ptr = &aiocb1[i]; ret = sigaction( SIGIO, &sig_act[i], NULL ); off+=100; list[i]=&aiocb1[i]; } void aio_completion_handler( int signo, siginfo_t *info, void *context ){ int i=0,ret; if (info->si_signo == SIGIO) { ..... } } It calls the aio_completion handler once when all the i/o requests are completed and we check the signal and proceed. The same method if I use for callback using threads, then it calls the aio_completion handler MAX times instead of calling it only once. aiocb1[i].aio_sigevent.sigev_notify = SIGEV_THREAD; aiocb1[i].aio_sigevent._sigev_un._sigev_thread._function = aio_completion_handler; .... void aio_completion_handler( sigval_t sigval ) { ... } How do I do something similar to signal mechanism whereing a check if the signal is mine and then only proceed. In short, how do I guarantee that aio_completion_handler is called only once in case of list AIO. Please help me out of this. Thanks and regards, Suresh --------------------------------- Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. --------------------------------- Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now.