Re: Problem with awaitTermination in ThreadpoolExecutor.

Hi,

The javadoc for awaitTermination in ExecutorService and
ThreadPoolExecutor includes the following:

Description
Blocks until all tasks have completed execution after a shutdown
request, or the timeout occurs, or the current thread is interrupted,
whichever happens first.

Returns:
true if this executor terminated and false if the timeout elapsed
before termination

We have occasionally noticed that awaitTermination returns true when
tasks submitted to the executor are still running, a timeout has not
occurred, and the submitting thread was not interrupted. This has been
an infrequent occurrence, but when it happens it severely impacts our
application. Our log clearly shows the condition (log messages from
Runnables exist after the awaitTermination returned true), and the
application behavior reflects the result of this condition (failures
due to threads still running when it is expected that the threads
have completed).

Below is the relevant code. (In this instance the tasks are
downloading files from an FTP site using a 3rd party FTP library, one
file per thread.)

Can anyone point out anything in this code that might cause the
problem, or suggest how we might refactor the code so the chances of
the problem occurring are reduced, or let us know if you recall a
bugfix for a problem like this ? We are using java build 1.6.0_11-
b03.

         // Create thread pool
    ExecutorService downloadThreadPool = new ThreadPoolExecutor(
        3, // corePoolSz
        5, // maxPoolSz,
        7, // keepalive (7 days)
        TimeUnit.DAYS,
        new LinkedBlockingQueue<Runnable>(),
        new ThreadFactory() {
            public Thread newThread(Runnable r) {
            Thread t = new Thread(r);
            t.setDaemon(false);
            t.setName("XF-Download-Thread-Pool");
            return t;
            }
        });

    //The application creates many Runnables and then executes the
following line in a loop for each:
    // (code to create Runnables not shown here)
    downloadThreadPool.execute(aRunnable);

    // Make threadpool wait up to 7 days for Runnables to end, after
which a threadpool timeout will occur.
    downloadThreadPool.shutdown();
    try {
        if (!downloadThreadPool.awaitTermination(7, TimeUnit.DAYS)) {
            Log.log(SPLogger.LogLevel.WARNING, "Threadpool timeout occurred",
SPLogger.LogPhase.UNKNOWN);
        }
    } catch (InterruptedException ie) {
        Log.log(SPLogger.LogLevel.WARNING, "Threadpool prematurely
terminated due to interruption in thread that created pool",
SPLogger.LogPhase.UNKNOWN);
    }

Thank you,

Tom Vicker