Thread: Multi Thread Program Problem

  1. #1
    Registered User
    Join Date
    Jan 2009

    Multi Thread Program Problem


    I'm developing a multi-threaded program in C.
    I have a thread - a dispatcher responsible for receiving information from a pipe and sending it to three other threads
    I used conditional variables to (try) to synchronize the program, but I'm having some problems.

    For a start I used pthread_cond_signal()

    Multi Thread Program
    while (letMeWork == 0) {
             puts("COMPRESSOR BLOCKED");
             pthread_cond_wait(&cond, &mutex)
    while (letMeWork == 0) {
             puts("ENCRYPTOR BLOCKED");
             pthread_cond_wait(&cond, &mutex)
    What I'm trying to do is: when I receive something in the pipe (the filename) the thread dispatcher sends a signal to thread1 in order for this to compress the file, after that the thread2 will work in that same file (modified by thread1).
    Note, I could have different files, so thread1 is compressing one file and thread2 is encrypting another.

    The problem is that, after receiving a signal, only thread1 works.
    I've tried with broadcast() but in that case it's worse...

    Any help is very welcome,


  2. #2
    and the Hat of Guessing tabstop's Avatar
    Join Date
    Nov 2007
    Perhaps I've gotten confused in the description, but don't you need two signals -- dispatcher sends a signal to compressor and compressor sends a signal to encryptor?

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