Re: Adding a timeout to commands by wrapping + thread - suggestions?

From:
 Daniel Pitts <googlegroupie@coloraura.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 03 Sep 2007 15:56:04 -0000
Message-ID:
<1188834964.809293.145840@57g2000hsv.googlegroups.com>
On Sep 3, 4:33 am, dduck <anders.johan...@gmail.com> wrote:

Follow-up:

By changing the execute method like so:

    public void execute() {
        Thread cmdThread = new Thread(new
CommandRunnable(wrappedCmd));
        Thread.currentThread().setUncaughtExceptionHandler(new
OverrideThreadGroup());
        cmdThread.start();
        try {
            cmdThread.join(timeoutL);
        } catch (InterruptedException e) {
            throw new RuntimeException(
            "I was interrupted while waiting for encapsulated command
to "
            + "join or timeout to expire");
        }
        if (cmdThread.isAlive()) {
            onTimeoutCmd.execute();
        }
        try {
            cmdThread.join();
        } catch (InterruptedException e) {
            throw new RuntimeException(
                "I was interrupted while waiting for encapsulated
command to join");
        }
    }

...I now get the re-.thrown exception, BUT not instantly. The output
is:

Throwing now
Exception in thread "Thread-0" java.lang.RuntimeException: I threw in
the towel
        at dk.kb.doms.experimental.ThrowingCmd.execute(ThrowingCmd.java:7)
        at dk.kb.doms.experimental.CommandRunnable.run(CommandRunnable.java:
17)
        at java.lang.Thread.run(Thread.java:613)
Command was executed just fine

I.e. the exception is thrown, but stil not in the main thread.

I guess if all I want is a log message when a command has executed
past the timout I should use a TimerTask instead?


Take a look at the Executor class and the java.util.concurrency
packages.

An Executor will return a Future object, which you can get the return
value of your work unit, or the exception that it throws.

Alternatively, you can wrap your whole run method in a try {} catch
(Throwable t) { }, and save the throwable for your main thread to
handle after the fact. I would *not* suggest this approach.

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