perl and threads

Discussion in 'Perl Misc' started by kristoff bonne, Jul 18, 2006.

  1. Aan allen die zijn of zullen zijn, onze groet.

    I don't know if this is the correct place for this, but I'm looking for
    some information about perl threads.

    I've been looking into perlthrtut and the other manuals for this, but I
    don't see to find the solution.

    If it is off-topic, please point me to a more correct newsgroup or forum.

    My question is this:

    Is there a way to get 100 % certainty if a thread is running.

    What I want to do is this:

    I have a program that makes a number (actually eigth) of ssh-sessions to
    a number of servers using the net::telnet module. On the servers, they
    read the log-files to get some information using a "tail -f".

    Now, I've got a thread (called "sshmaster") in my main program which
    starts up the 8 ssh-session (called "sshsession"); each as a seperate
    These sub-thread communicate back to "sshmaster" for control-messages
    (e.g. connection established, connection failed, connection interrupted)
    using a queue.

    So far, so good. And it does seams to work pretty-much OK, ... as long
    as the ssh-sessions behaviour as they are supposted to do.

    But, I want to be sure that the sub-threads do keep on working OK, and
    -when a subtreads dies for whatever reason- that "sshmaster" is able to
    check this.

    I see different possibilities:
    1/ sent a control-message from the sub-thread to sshmaster over the
    message-queue. However, this will not work if the subthread dies for an
    unknown reason and it might not be able to sent a message to sshmaster.

    2/ lock a variable (which will automatically unlock when the thread
    dies), but sshmaster is not able to check if a variable is still locked
    without blocking.

    3/ As "sshmaster" has a list of all its subthreads, ask a system if a
    thread is still alive. But HOW????

    The only way I see is by locking a file using the "flock" mechanism but
    that'a a bit "overkill" if you ask me.

    Anybody any other ideas?

    Cheerio! Kr. Bonne.
    kristoff bonne, Jul 18, 2006
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  2. Guest

    kristoff bonne <> wrote:
    > 3/ As "sshmaster" has a list of all its subthreads, ask a system if a
    > thread is still alive. But HOW????



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