I see, so if I do not wish to manage the lock references myself, I (and LeRoy
also) should always obtain locks through a LockManager.
Aaron
Oliver Zeigermann wrote:
By the way, when giving me first advice I stumbled over exactly this
difference between the lock manager and the lock itself...
Oliver
On 7/6/05, Oliver Zeigermann <[EMAIL PROTECTED]> wrote:
You are right, but only for the lock manager. The lock manager takes
care of uniquely mapping a resource id to a lock, but when you work on
a lock *directly* it must - of course - be the same object.
Oliver
On 7/6/05, Aaron Hamid <[EMAIL PROTECTED]> wrote:
Is this true? It was my impression, have first written such a class, and then
finding and skimming the javadoc for [ReadWrite]LockManager, and particularly
'getLock' and 'createLock', that lock singletons would be automatically created
and managed. Otherwise the developer must write a lot of boilerplate code for
keeping a singleton map of locks. Surely only the 'resourceId' must be the
same, and not the actual ReadWriteLock reference?
LockManager: "Encapsulates creation, removal, and retrieval of locks. Each resource
can have at most a single lock."
Aaron
Oliver Zeigermann wrote:
Ooops, sorry, you are right. Not only the resource Id, but the lock
*itself* must be the same in both threads.
Doing it this way:
final ReadWriteLock fileLock = new ReadWriteLock("Huhu",
loggerFacade);
Runnable run = new Runnable() {
public void run() {
try {
System.out.println("before acquiring a lock
"
+ Thread.currentThread());
boolean result =
fileLock.acquireWrite(Thread
.currentThread(),
Long.MAX_VALUE);
System.out.println("lock result: " + result + "
"
+ Thread.currentThread());
Thread.sleep(20000);
System.out.println("after sleeping "
+ Thread.currentThread());
} catch (InterruptedException e) {
e.printStackTrace(System.err);
} finally {
fileLock.release(Thread.currentThread());
}
}
};
Thread t1 = new Thread(run, "Thread1");
Thread t2 = new Thread(run, "Thread2");
t1.start();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
t2.start();
works fine for me.
HTH
Oliver
On 7/6/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Oliver,
I tried your suggestion by changing my ReadWriteLock statement to
ReadWriteLock fileLock = new ReadWriteLock("c:/logRec.txt",loggerFacade);
However, I received the same results as when I used new File(..).
LeRoy
Oliver Zeigermann
<oliver.zeigerman
[EMAIL PROTECTED]> To
Jakarta Commons Users List
07/06/2005 01:44 <[email protected]>
AM cc
Subject
Please respond to Re: Transaction API, ReadWriteLock
"Jakarta Commons
Users List"
<[EMAIL PROTECTED]
arta.apache.org>
Most likely your problem ist that new File(..) creates different
objects in each thread. I would try using something like the path to
the file as String.
Oliver
On 7/5/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
I'm trying to use the ReadWriteLock class to acquire a write lock on a
file
in a servlet. When I generate multiple threads of the servlet using a
WTE
5.1 server in the WSAD 5.1 IDE, I'm not able to get ReadWriteLock to
block
other servlet threads after the first servlet thread obtains the lock.
I'm
using two IE browser windows to generate the two servlet threads. Below
is
ReadWriteLock code I have in the servlet followed by the
System.out.println
statements that are generated in the server log file during my test.
ReadWriteLock fileLock = new ReadWriteLock(new File(c:/logRec.txt,
loggerFacade);
try {
System.out.println("before acquiring a lock " +
Thread.currentThread());
boolean result =
fileLock.acquireWrite(Thread.currentThread(),Long.MAX_VALUE);
System.out.println("lock result: " + result + " " +
Thread.currentThread());
Thread.sleep(20000);
System.out.println("after sleeping " + Thread.currentThread());
FileWriter recFile = new FileWriter(c:/logRec.txt, true);
recFile.write("text from testFileTran");
recFile.close();
} catch (InterruptedException e) {
e.printStackTrace(System.err);
} catch (IOException e) {
e.printStackTrace(System.err);
} finally {
fileLock.release(Thread.currentThread());
}
[7/5/05 8:26:03:326 CDT] 7c1477e SystemOut O before acquiring a lock
Thread[Servlet.Engine.Transports : 0,5,main]
[7/5/05 8:26:03:326 CDT] 7c1477e SystemOut O lock result: true
Thread[Servlet.Engine.Transports : 0,5,main]
[7/5/05 8:26:08:384 CDT] 24c3477d SystemOut O before acquiring a lock
Thread[Servlet.Engine.Transports : 1,5,main]
[7/5/05 8:26:08:384 CDT] 24c3477d SystemOut O lock result: true
Thread[Servlet.Engine.Transports : 1,5,main]
[7/5/05 8:26:23:335 CDT] 7c1477e SystemOut O after sleeping
Thread[Servlet.Engine.Transports : 0,5,main]
[7/5/05 8:26:28:382 CDT] 24c3477d SystemOut O after sleeping
Thread[Servlet.Engine.Transports : 1,5,main]
From reviewing the Transaction documentation and mailing list archives,
I'm
not able to determine what I'm doing wrong.
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