I would appreciate your help in understand a "Concurrency Example" from:
http://forums.sun.com/thread.jspa?threadID=735386
Qute Start:
public synchronized void enqueue(T obj) {
// do addition to internal list and then...
...
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I learned that calling an Object's wait() method will release the object monitor, if present.
But I have some questions regarding calling notify() on this object by another thread:
- (when) will the waiting ...
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Specifically, can somebody tell me what is wrong with this piece of code. It should start the threads, so should print "Entering thread.." 5 times and then wait until notifyAll() is ... |
I have a serial port with data coming in. I implemented the serial port connection with RXTX library with a serial port event listener. So whenever there is incoming data available ... |
As far as I know, wait() and notify() have been replaced with better concurrency mechanisms. So, what better alternative would you choose, say for implementing a synchronized queue?
In what sense ... |
I know the mechanism of wait() and notify() of thread, but I am unable to understand that why wait() and notify() methods should be in synchronized block? Is this mandatory?
Thanks in ... |
I'm trying to create a class in java that pool objects. The class starts creating the minimum amount of objects required, when the requests start to kick in, every thread checks ... |
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I have an object on thread A that is calling wait() while another object on thread B does some work then calls thread A's object's notify(). Thread A then performs some ... |
class Semaphore {
private int count=100;
public Semaphore(int n) {
this.count = n;
}
public synchronized void acquire() ...
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I know that this is a repeated question. But I am unable to understand by the explanation.
I want to understand it cleraly with a well example. Can any one please ... |
wait() doesn't release all locks; it only releases the lock of the object upon which it is called. Therefore, calling it without actually owning the lock on an object doesn't make sense. If you're in a block or method that synchronizes on an object, then you own the lock on that object, of course; hence the requirement. Note that the actually ... |
Notify tells some object that is waiting on a monitor that the monitor is about to become available. Only the owner of the monitor can do this because only the owner knows when it's about to give the monitor up. From the JavaDoc This method should only be called by a thread that is the owner of this object's monitor. A ... |
Say my class has a synchronized method and one thread is executing the method. A second thread that tries to execute the same method has to wait until the first thread completes. Now, after the first thread is done executing the synchronized method, will the second thread be notified automatically? Or, do I have to explicitly notify() at the end of ... |
Hi All, I am not sure if this is a naive question, I would greatly appreciate if someone could explain with a code example to solve the question below There are two methods one synchronized and other non-synchronized e.g. public synchronized void m1() { } public void m2() { } Suppose there are two Threads T1 and T2 accessing the above ... |
There must be some sort of synchronization. Both these method will throw an IllegalMonitorStateException if called from code that doesn't already hold the lock for whatever object is being used to invoke wait() or notify(). Which meanse that in order to have previously acquired this lock, you must be inside a synchronized block or synchronized method. Or, inside a method that ... |
Okay Pete here it is - about 200 words, however. Jim ... ... Threads & Data Consistency An executing thread is time sliced by the JVM, from start() until the end of its run() method. To run a thread after another thread completes, just join() the other thread. Call yield() to pause a thread. This relinquishes some of its time slices ... |
Hi Forgive me for my ignorance but as far as I can understand we use notify() method to indicate other threads that the current thread is done with its work here. However the same purpose can be achieved by using synchronized block as the the other threads will be free to run the sunchronized block once the current thread has exited ... |
Madhan Sundararajan Devaki wrote:Are you expecting a CNC program using Java or are you expecting how this scenario should be modelled using OOP methodology? Volatiles are best suited for primitive data types. An instance variable declared volatile ensures that the update operation on it is atomic. Thanks sir for giving me your precious time... sir i want to know how this ... |
Apart from all the other uncorrected bugs described above, the server probably cleared it after the receiver set it, because you're not sequentializing that part of it properly. The server should clear it first, then send the message, then wait() until it's set or a timeout happens. But what exactly is the point? In a real client/server there wouldn't be any ... |
Can i replace above code by the code below and expect the same output. If yes, please could you just explain me breifly how was it possible as we are not creating any specific objects. I don't know how to use "this" keyword effectively I guess "this" would mean synchronized this method. ?? |
} } The method causes in infinite loop, I believe this is happening because the notify is being called before the dialog window has completed then when the wait is set up there is no notify to come. My problem is the wizard is used in other circumstances where it will not look for this. Would it be okay to add ... |
It sounds like, in the case where it doesn't work, you're calling it from the dispatcher thread (probably from a actionListener or the like). If you call wait() on the dispatcher thread the GUI will freeze and not respond to clicks etc. until the wait exits. Since you're depending on a button click to end the wait, you're deadlocked. If you ... |
I don't want to use wait/notify, but I believe it would be a much more complicated task to split the algorithm in the 2nd class in two so I can't (don't want to) convert it that way. Good point about the String and that I exchange the object, not just a value. I hope it will work, will try this now ... |
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I would sugegst you start with the simplest structure you can. I would use plain blocking IO with one thread per client. Get this working first before you attempt sucha complex structure which can be tricky to get right. BTW: readLine() methods and non-blocking IO don't mix very well as you may have an incomplete line which you need to combine ... |