Good day!
I got the problem about synchronizing threads in java. I am developing program which creates timers and allows to reset it, delete and stop. Just to learn how to using ... |
I need to synchronize two large sets of strings in Java, one of the on the client and the other on the server. Most probably the client is missing a couple ... |
How can I synchornize two Java processes running on Windows ?
I am looking for something like the Win32 Named Mutex object which allows two processes to use the same locking object.
Thanks
... |
When using the apache commonds bidimap, how do you handle synchronization. For example, if I create the map as shown below
BidiMap oneWay = new DualHashBidiMap();
BidiMap theOtherWay = oneWay.inverseBidiMap();
So if I ... |
I have three methods that all access the same files in on folder.
I use PersistenceStrategy com.thoughtworks.xstream.persistence.XmlArrayList
The thing is that many threads can do write,read,delete using any of the four methods
witch all ... |
How to synchronize method in java other than using synchronized keyword?
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I would like to iterate over a java List using the old fashion for(int i...) loop, since for a given i and loop iteration, I want to access several elements relative ... |
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I'm trying to solve a Java synchronization problem. The case is as follows:
There are class Persons and they want to be paired. So I have a class Coupling that does the ... |
I have an assignment for developing a messenger for 1 server and 3 clients. I am facing a problem with time synchronization: I have to synchronize the server time with the ... |
I am working on a large scale dataset and after building a model, I use multithreading (whole project in Java) as follows:
OutputStream out = new BufferedOutputStream(new FileOutputStream(outFile));
int i=0;
Collection<Track1Callable> callables = new ...
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Sometimes when I need lazily initialized field, I use following design pattern.
class DictionaryHolder {
private volatile Dictionary dict; // some heavy object
public Dictionary getDictionary() {
...
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I'm writing an application that draws certain shapes.
Before each shape is drawn, some calculations are to be made. Which is why I have another thread to draw already processed items.
To synchronize ... |
I'm implementing a network thread manager for my application. I have created a JUnit test, which rapidly requests and releases a network thread index by invoking the following two methods:
protected static ...
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A web application queries an external server. If more than 80% of the requests to the server send within the past 'n' minutes fails, then the web applicatoin should back ... |
I have the following sample piece of code,
public class test implements Runnable{
public void run()
{
synchronized(this)
{
...
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The class java.lang.ThreadInfo provides some very useful methods which provide statistic concerning synchronization in Java. For instance:
getBlockedTime() Returns the approximate accumulated elapsed time (in milliseconds) that the thread ... |
I am making a client server MMO style game. So far I have the framework set up so that the server and clients interact with each other in order to provide ... |
I am bit stuck here, I have to have edit this code so that a train must wait in front of the tunnel lock for a train to come in the ... |
I am developing under Java, Ejb3.0, WebLogic.
I would like to have a system design suggestain from you about feature which I am going to develop. (not too complicated)
The main goal is ... |
I have a nested set within a map within a map that I am trying to synchronize over two threads.
The map is instantiated as such:
private final Map<Manageable, ...
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I tried really hard to search for information about the issue, but nothing was relevant.
Any contribution will be appreciated.
DataStructure ds = new DataStructure();
public synchronized void run() { b(); }
private void b() ...
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I have following situation. I have a class for accounts, each account has a balance and money can be transfered to it.
public class Account {
private int balance;
...
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I've an application written in J2EE+Spring+Hibernate (call it app1), now my boss wants that another application (app2, totally differente and written with different technologies), could regularly and automatically sync with it ... |
I'm looking for a java library (not tool) that will provide synchronizing local directory with directory on server (ftp). What I need is to put a set of files on server ... |
I am new to thread programming in Java. To understand threading I'm trying to write a simple program to simulate a bank account. I just implemented withdrawal and trying to test ... |
i have 2 audio input of a concert.
The first is a wav file and the second is taken by microphone in real time.
I need play the first file in synch with ... |
Hi guys I have the following.
class a extends Thread
{
public synchronized BigInteger getUniqueID()
{
...
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Suppose our application have only one thread. and we are using StringBuffer then what is the problem?
I mean if StringBuffer can handle multiple threads through synchronization, what is the problem to ... |
I'm writing conjugate-gradient method realization.
I use Java multi threading for matrix back-substitution.
Synchronization is made using CyclicBarrier, CountDownLatch.
Why it takes so much time to synchronize threads?
Are there other ways to do it?
code ... |
I have an JEE application which is clustered on two WebSphere V7 nodes. If a client changes data which is persisted to a database on node 1, I want to make ... |
What is the difference between synchronizing a static method and a non static method in java?Can anybody please explain with an example. Also is there any difference in synchronizing a method ... |
Looking at the javadocs it just says
<T> Future<T> submit(Runnable task, T result)
Submits a Runnable task for execution and returns a Future representing that task. The Future's ... |
I have a multithreaded class A which accesses the following insert() method of another class B (A has only a single instance of B).
Instead of making the entire method synchronized, are ... |
i have a question, what is difference between
StringBuilder sb = new StringBuilder();
public void sync(){
synchronized(sb){
};
}
and
public void sync(){
synchronized(this){
};
}
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All of you know the synchronization context in Java that they are can be
- on the instance.
- on the java.lang.Class instance for a certain loaded class.
- on a given object
And I need to ... |
I need to stream multiple videos in a web browser and have them all be synchronized; I also need to be able to switch between audio channels on the fly. ... |
I have the following 2 classes code that produce this result for instance:
Wainting for calculation to complete...
Calculator thread says HELLO!
T1 says that total is 10
Wainting for calculation to complete...
Wainting for calculation ...
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I'm having some issues with java multithreading, best explained on an example:
class Thread1 extends Thread
{
boolean ...
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I am using gemfire and currently have a client and a server. Now, the server dinamically creates some subregions in a region and puts some objects in there. I am trying ... |
I'm wondering about writing an application in Java which can synchronize files across my devices automatically (desktop, notebook, smartphone). Similar to Dropbox, however without a 3rd party server because i own ... |
I wan't to be sure that some piece of my code within the main thread will be executed after some piece of code executed withing the secondary thread. Here's what I ... |
I have an Executor (obtained via Executors.newFixedThreadPool(int)). I would like to run some arbitrary code whenever a) the queue is empty and an item is inserted into the queue, and ... |
I have gone through the below links
Problem with synchronizing on String objects?
and
http://illegalargumentexception.blogspot.com/2008/04/java-synchronizing-on-transient-id.html
Now my question:
- I have a map where userid and a list of some properties are maintained
- when we ...
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I started trying to learn tdd and wanted to use it on a real project. So I decided on programming a simple file synchronization with a client and a server in ... |
public class PingPong implements Runnable {
synchronized void hit(long n) {
for (int i = ...
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The setup:
I am in the process of changing the way a program works under the hood. In the current version works like this:
public void threadWork( List<MyCallable> workQueue )
{
...
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How to implement bidirectional sinchronization between two bound properties? The utility class PropertyChangeSupport provides a trivial mechanism that avoids infinite loop. In some cases I find it to be insufficient. Is ... |
When a synchronized block is used for synchronization on an object instance, then threads compete to get into object's implicit monitor. And once, any particular thread enters into the monitor, any ... |
After reading topics here about Java synchronized methods, I've tried to implement it in my multiplayer game because many threads are opened and trying to access the same resource.
I've made methods ... |
I use an integer as counter. The integer will only be increased, and surely more than one thread will increase it at the same time. The value of this counter is ... |
I have the following codes. It is throwing me a java.lang.IllegalMonitorStateException. Why is that and how do I solve this?
public class Threads {
/**
...
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I am trying to find out if there is going to be any race condition in this piece of code. If the key weren't 'Thread.currentThread' then I would think yes. But ... |
i have some small problem.
I hava some class Processor and Process. Process class have only name and value
Processor must calculate this value and display it. In turn, Processor implement Runnable interface
But ... |
I have to multithread a method that runs a code in the batches of 1000 . I need to give these batches to different threads .
Currently i have spawn 3 ... |
I have 2 machines both running one process each. shell process on Machine A will scp something to machine B, and java process on B will use these files. Both processes ... |
When we declare a method synchronized then how it is known by second thread that the synchronized section of code used by the first thread is completed and how second thread ... |
Any ideas on the best way to block all adds once stop has been called?
Also, this is the first time I have ever used LockSupport is this the best way to ... |
I am a bit confused with the requirements to synchronize the access the private instance variables in java.
I have an applicaion which executes scheduled tasks multithreaded. These tasks (instances of ... |
How it is possible that both static and non static java synchronized method running in parallel while writing java synchronized code ?
public class Counter{
private static count = 0;
...
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Let's say you have the following class:
class A {
private Foo foo = new Foo();
Foo getFoo() {
...
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I would like to perform the following algorithm - this must be done in Java
for(int i = 0; i< 100; i++){
create 8 threads which perform a task
...
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try{ this.wait();}catch (Exception e){} First off all: NEVER ignore exceptions, try writing try{ this.wait();}catch (Exception e){ e.printStackTrace(); } and look what is happening. |
answered by pbrockway2 What the API docs say is "Causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread. The result is that ... |
Not necessarily. Another thread could be running another method which also changes those values. You have not locked on the object itself or its members, just the method. |
I really wouldn't synchronize the entire remote method... This means that only one client can be active in the method at a time and it can create a bottleneck. You may want to synchronize important sections inside your methods if you're updating multiple rows/tables/etc. within one transaction. On the other hand, depending on what you're doing, the database may be able ... |
Hi, The problem is regarding using single instance for all the threads created. Description: I am having a .zpy on the server.when this file is downloaded my first login screen should be invoked on the client machine and a thread will be created.Assume the application exists on the client machine.we are able to do this,ie I can associate the file types ... |
what is meant by synchronization? why synchronization is associated with threads? can we use synchronized methods without threads? these are the doubts i face and this doubt struck me when i came accross this problem given below?please help public class A { public static void main(String args[]) { new A.method(); } public synchronized void method(){} }//class A class B extends A ... |
when you create an object like this a first=new a(); a second=new a(); while a is declared as class a{ int i; public void p(){ } } please take note of the fact that in memory only one copy of the class exists , Thus there is only one method by the name p() in memory. while as many copies of ... |
I was wondering what would happen if: I have a thread that has a lock on a synchronized method. This thread never dies (is in a continual while loop)and is only put to sleep. So as i understand it this thread should never give up its lock. If this thread never gives up its lock on the synchronized method what will ... |
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class Test implements Runnable { public static void main(String[] args) { Test t1=new Test(); } Test(){ Thread thread1=new Thread(this); thread1.start(); nonsynchronized(); } public synchronized void run(){ int temp=0; while (temp<1000){ System.out.println("in synchronized method " +temp); temp=temp+1; } } public void nonsynchronized(){ int temp=0; while(temp<1000){ System.out.println("in non synchronized method" +temp); temp=temp+1; } } } |
Sunita, What you specify can be done. However it comes at a cost where there is no benefit. An application that does not undertake concurrent access does not require synchronization. Only when threads come into the picture is the need for synchronization. To cite an example. We have both the Vector and the ArrayList. Both do the same things. They store ... |
I have a vector to hold locked records. Multiple clients can access this vector. I need to write lock() and unlock() methods. Instead of synchronizing whole methods Im planning to use synchronized blocks. Im wonedring if my logic is okay. Im not that good in threads. Lock(int recordnumber) { while(true) { If record not exists in vector ... |
What I understand about synchronizing threads is, the first thread executes the synchronized method or block and the other threads wait on the lock. Once a thread has done with its work, it has to do a notify or notifyAll on the lock and other threads get a chance. So, I thought without notify or notifyAll, other threads will wait for ... |
There is only one synchronization construct in Java and that is a lock/Monitor pair. A block(peice of code) or a set of blocks that need to be synchronized should be associated with a lock_object. Every thread that needs to execute that block (critical section) needs to acquire a monitor over the lock_object. Whoever gets the monitor on the lock executes. The ... |
Hi! Well i ve a server that threads out a new object of the same as soon as it recvs a connection.. Well each of these threads have to write a value in xml format into a file. I have synchronized the method to write to xml.. but then the server threads still fail toi write into the file.. I guess ... |
continue on the previous issue.. synchroniztion on thread object does fail too.. package synchron; public class synThread1 { public static void main(String args[]) { Xyz r = new Xyz(); Thread t1 = new Thread(r); synchronized(t1) { t1.start();} Thread t2 = new Thread(r); synchronized(t2) { t2.start();} Thread t3 = new Thread(r); synchronized(t3) { t3.start();} Thread t4 = new Thread(r); synchronized(t1) { t4.start();} ... |
Guess what.. when I go one step further to name each thread, no more need for synchronizaion.. Multi-threading are kicking good without any more over-run.. package synchron; public class synThread1 { public static void main(String args[]) { (new Thread(new Xyz(" a"))).start(); (new Thread(new Xyz(" b"))).start(); (new Thread(new Xyz(" c"))).start(); (new Thread(new Xyz(" d"))).start(); (new Thread(new Xyz(" e"))).start(); (new Thread(new Xyz(" f"))).start(); ... |
The properties should be no more than hashtables in disguise, so they are OK. The use of a Vector makes me wonder how you are finding your cached values in that Vector. If you're doing a linear search, then you've traded an O(1) algorithm for an O(n) one -- almost always a bad move. Try a sorted data structure and a ... |
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I'm having an issue with JavaBean synchronization. My java beans have all public methods marked as synchronized, and I have all the fields in my bean class as private. I have a default no arguement constructor. This bean is used by my servlets to store data temporarily. The issue is that if two people log in concurrently to the same set ... |
I have a TicTacToe game which is played betwee 2 players and a server manages the rule base.. I dont understand a part of the code. I am providing a link to the code as well, but for simplicity i shall write the code for the Server and the Client here itself.. it will make my message too long, sorry for ... |
I was reading some articles abt threads. I came across the statement, When a class with synchronized method is instantiated, new object is given monitor. That is, once a thread enters a monitor all other threads must wait until the first exits. Now suppose i have a class that extends Thread and if i have synchronized method inside it, then does ... |
Here is a description of the problem. I have a list of objects (Strings) in a HashSet. This list can be very long (can contain thousands of entries). Several identical threads can be concurrently running (one for each client) who may ask to add an entry to the set (public static void addToList(String x)) or may want to check to see ... |
Hi. I apologize for the lengthy post, but at least this way you have all the code. // contents is a Vector... // db is a Data Access object. public Vector getList() { return getList(contents.size()); } public Vector getList(boolean forceRefresh) { if (forceRefresh) { refresh(); } return getList(); } public Vector getList(boolean forceRefresh, int maxItems) { if (forceRefresh) { refresh(); } ... |
Hi! I have a synchronization question: I have the following code: int waiting = 0; object obj = new Object(); public void foo() { waiting++; synchronized (obj) { waiting--; ... } } Of course that when many threads try to enter that method, only the first will succeed and that other will wait at the synchronized block. My question is that: ... |
Hello all! I have an object that I recieve via JMS. I store that object in a HashTable. When a certain event happens, I run that cached object. Can I synchronize the object when I put it into the cache, there by making it always synchronized, or do I have to synchronize the object after I get it out of the ... |
Vic If each thread has its own instance of a foo object what is there to synchronize? Or is there some class member that needs to be synchronized in the foo object? If it is a class (static) member of class foo just create getter and setter methods in the foo class and synchronize the methods - or just part of ... |
hi all i am using a user defined exception in my project to indicate whether the operation done by a particular method is a success or a failure. A large no of components are goin to use this exception for signalling of the failure thru a log writer which will throw the exception the flow is somewhat like this Component.method(fails)>>LOGWriter.StaticMethod()>>MyException. * ... |
IMHO, ie. a HashTable is already synchronized: public synchronized void modify() { m_hashTable.put(new Object(), "key"); } the synchronized keyword is redundant in this case since a thread has to obtain a lock on m_hashtable to invoke a put. So modify() need not be synchronized. 1. [I]Synchronized method[/I] public synchronized void modify() { m_hashMap.put(new Object(), "key"); } 2. [I]Synchronized code block[/I] public ... |
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Hi all, Can someone please set me straight on a few synchronization concepts? Are method variables thread-safe? I thought I read that method variables are thread-safe, but I am not yet fully convinced this is true. I read servlet "service requests" get their own instance, and because of this are thread-safe. Although I have encountered threading issues in servlet doGet and ... |
Hi, I am writing a client server application to send an audio file to server and Server will send that file to Client2. I need to calculate the time when the packet start from client1 and reaches server. Since my Clients and Server will run on different m/c's so i won't be having the synchronized clock. System clock on different m/c ... |
I am aware that synchronizing on an object costs a certain amount in terms of performance. If however I have an object and I know my code is the only place with that object reference what kind of performance hit do I incurr if I synchronize on it. Is it so small as to be almost insignificant? I know this sounds ... |
It's been awhile since I've done this so I just want to make sure I'm doing this right. I have a global static HashMap that I do puts and gets to (no removes). I declare them like this: public static Map myMap = new HashMap(); public static Map myMap_sync = Collections.synchronizedMap(myMap);// for adding later When I want to get something out ... |
here there are actually two aspects whether u are referring to the threads in the entry set or referring to the threads in the wait set. If at all there are threads in the entry set there will be a competition between the two threads one in entry set and one in wait set .But when a thread releases the lock ... |
Is it possible to synschronize a method so that whether it gets called by a Thread or an ordinary method, it will wait until the first one is finished with it? I've just tried this by sticking the synchronize keyword on a method but it seemed to make no difference. If it is possible, do I need to do more than ... |
I am having issues with understanding synchronized blocks. I thought if a block was synchronized the thread that was accessing it has control until it is finished with that block of code. Why does it print: first0 second0 first1 second1 first2 second2 instead of: first0 first1 first2 second0 second1 second2 ********************************************* public class Holt extends Thread { private String sThreadName; Holt(){} ... |
Whats the effect of synchronize on thread? class thread1 { public static void main(String[] args) { x first =new x(); Thread new1=new Thread(first); Thread new2=new Thread(first); new1.start(); new2.start(); System.out.println("Hello World!"); } } class x implements Runnable { boolean x=true; public void run(){ while (true) { synchronized(this){ System.out.println("changing threads"); try { int i; for(i=0; i<10; i++){ System.out.println(i +" " + Thread.currentThread().getName()); } ... |
Hello, I wonder when to synchronize a method. Please consider this: public class Question47a implements Runnable { static int i=0; //i is class variable public static void main(String[] args) throws Exception { Thread t1 = new Thread(new Question47a()); Thread t2 = new Thread(new Question47a()); t1.start(); t2.start(); } public void run(){ for(int y=0;y<5;y++) new Question47a().aMethod(); } public synchronized void aMethod() { //In ... |