Re: [Threading to manage simulated printing jobs]

Joshua Cranmer <>
Sun, 09 Sep 2007 18:28:33 GMT
<lXWEi.340$Z33.181@trndny08> wrote:

Here I have written a program which simulates a printing job in which
'Consumer' is a printing device or software and 'Producer' submits a
printing job. But the output I get is highly deterministic i.e. the
same everytime I don't even know if I have got it right or wrong. Some
comments / pointers / alternate designs / tips / revelations would be
greatly appreciated.

What is the output?

class Consumer {
    private Runnable job = new Runnable() {
        public void run() {
            // start consuming the print jobs and print them
            try {
                for (;;) {
                    //System.out.println("Inside run of producer");
                    PrintJob job = queue.getJob();
                    if (job != null)
                        System.out.println(id + job.print());
            } catch (Exception e) {
 > };

Two things:
1. Don't use tabs in Usenet posts.
2. There should typically be some way to tell the Consumer to stop running.

     public Consumer(PrintQueue queue) throws Exception {
 > [ ... ]

         t.join(); /* Does this even do anything? */
Joining a thread waits for it stop. Since the thread hasn't started yet,
it doesn't do anything.


[ ... ]

Try posting some of the output so we could help better.

Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth

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