Path: csiph.com!x330-a1.tempe.blueboxinc.net!aioe.org!nntp.cybernetik.net!usenet-01.nntp.cybernetik.net!news.glorb.com!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
From: Fly <flavio80@gmail.com>
Newsgroups: comp.lang.java.programmer
Subject: streaming problem and thread freeze
Date: Mon, 9 May 2011 07:56:15 -0700 (PDT)
Organization: http://groups.google.com
Lines: 105
Message-ID: <005a9e79-36fe-4bf1-aa1d-bda3a5aaebf2@glegroupsg2000goo.googlegroups.com>
Reply-To: comp.lang.java.programmer@googlegroups.com
NNTP-Posting-Host: 151.25.123.10
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
X-Trace: posting.google.com 1304952975 27339 127.0.0.1 (9 May 2011 14:56:15 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Mon, 9 May 2011 14:56:15 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=151.25.123.10; posting-account=E9yt5woAAAAjdPbKg8rPXAgEzMP_mDtP
User-Agent: G2/1.0
Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:3858

Hello, 
I have a client program that read an XML from a STREAM every 60 seconds.
From the main Thread I do an infinite loop where I create a new working thread
executing all the operations: read, parse, etc..

This is what I do:

<code>
 DownloaderTask tempTask = null;

        while (true) {

            if (tempTask != null) {
                if (tempTask.isAlive()) {
                    tempTask.cancel();
                }
            }

            tempTask = new DownloaderTask();

            tempTask.start();

            try {
                sleep(frequency * 1000);
            } catch (InterruptedException ex) {
                log.severe("Main sleep failed");
            }

        }

</code>

Inside the Run method of the DownloaderTask, I first read from the Stream (a class field) with a BufferedReader, in this way:

<code>
 private String readDocumentFromStream(BufferedReader reader) throws IOException {
            char[] buffer = new char[4 * 1024];
            int charsRead = -1;
            String retVal = "";
            log.finer("---START reading XML ---");

            while ((charsRead = reader.read(buffer, 0, 4 * 1024)) != -1) 
            {
                log.log(Level.FINER, "CharsRead: {0}", charsRead);
                retVal += String.copyValueOf(buffer, 0, charsRead);
            }
            log.finer("---STOP reading XML---");

            return retVal;
        }
</code>

In the DownloaderTask class I wrote a cancel() method, called by the main thread in the case the working thread was still alive after the sleep().


It's definition:

<code>
   synchronized public void cancel() {

            this.interrupt();
            try {
                if (rd != null) {
                    rd.close();
                }
            } catch (IOException ex) {
                log.severe(ex.getMessage());
            }

            http_conn.disconnect();

            log.log(Level.SEVERE, "Timeout. Thread {0} is being canceled and resource released.", this.getId());

        }
</code>

My problems.
 
Sometimes I see my program active, doing nothing, blocked probably in the read(), because if I check all logs, the last line written is "CharsRead: xxx" and no more.
Here I post one of my saved log (where the read buffer was 1024 bytes):

<LOG>
||-- 2011-05-03 06:44:59 FINE: Updating events data... --||
||-- 2011-05-03 06:44:59 FINE: Events updated! --||
||-- 2011-05-03 06:44:59 INFO: Release date: 2011-05-03 06:45:15 | Received: 187 Inserted: 0 Updated: 0 Deleted: 0 ||| Errors: 2 --||
||-- 2011-05-03 06:44:59 FINER: Normal closing thread 1.723 --||
||-- 2011-05-03 06:44:59 FINER: Thread 1.723 Closing --||
||-- 2011-05-03 06:45:52 FINER: Thread 1.725 Opening --||
||-- 2011-05-03 06:45:52 FINE: Opening server connection to: mysite.com:80 --||
||-- 2011-05-03 06:46:19 FINE: Reading From Stream --||
||-- 2011-05-03 06:46:19 FINER: ---START reading XML --- --||
||-- 2011-05-03 06:46:19 FINER: CharsRead: 1.024 --||
||-- 2011-05-03 06:46:19 FINER: CharsRead: 1.024 --||
||-- 2011-05-03 06:46:19 FINER: CharsRead: 1.024 --||
||-- 2011-05-03 06:46:19 FINER: CharsRead: 929 --||
||-- 2011-05-03 06:46:19 FINER: CharsRead: 1.024 --||
||-- 2011-05-03 06:46:19 FINER: CharsRead: 1.024 --||
||-- 2011-05-03 06:46:19 FINER: CharsRead: 872 --||
</LOG>

I noticed another strange thing in this log, that is I can't see the Thread Id: 1724.
Can you help me to find where I am wrong? In the logic or maybe in the syntax of the program?

Thanks in advance,
Flavio