By both running test programs and looking at source code, it is clear that the method, as implemented by Sun, does not simply yield time to the specified thread, but actually ... |
My program looked like this:
class Prog
{
BufferedImage offscreen;
KindOfDatabase db;
MyThread thread;
class MyThread extends Thread
{
volatile boolean abort=false;
long ...
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I have one main thread that starts 10 other threads. I want that the main thread will be finished only after all other threads stopped. So should I call join() on ... |
Suppose a thread A is running. I have another thread, B, who's not. B has been started, is on runnable state.
What happens if I call: B.join()?
Will it suspend the execution of ... |
I was reading this Sun's tutorial on Thread.
I found a block of code there which I think can be replaced by a code of fewer lines. I wonder why ... |
First of all here are some code snippets:
public void startThread() {
this.animationThread = new Thread(this);
this.animationThread.start();
try {
...
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How Join method work in Thread. If write join method in run method then its going to deadloack. Just need to information why its happening.
Code Snipet:
public class ThreadSchuduling extends Thread{
...
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I saw a stackoverflow member suggest using Thread.join() to have a "main" thread wait for 2 "task" threads to complete.
I will frequently do something different (shown below) and I want to ... |
In a multi-threaded java program, what happens if a thread object T has been instantiated, and then has T.join() called before the thread has started? Assume that some other thread ... |
I need to synchronize over several threads. I don't create the threads, but I do know how many there are. So I wrote this inner guarded block:
private class Guard {
...
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My Code
public class Main {
public static void main(String[] args)throws Exception {
Thread thread1=new Thread(new Runnable()
...
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When writing a multithread internet server in java, the main-thread starts new
ones to serve incoming requests in parallel.
Is any problem if the main-thread does not wait ( with .join()) for them?
(It ... |
What state is a Java thread in after you call join with a timeout value, and the timeout passes. So for instance you have the following code:
Thread thread = new ...
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the java thread join() mehtod confuses me a bit. I have following example
class MyThread extends Thread {
private String name;
private int sleepTime;
...
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I have the following issue with one of my Java programs.
I'm trying to launch several threads depending on what my main program find on the file system.
The way it works is ... |
I am in doubt, what happens when a thread joins itself. i.e thread calls the join method on its own. I am not getting any error.
Sample :
public class JoinItself ...
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Is using a join to wait until a Thread has finished the same as using the an observer to notify the calling thread class when the thread has finised ?
Using join ...
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I am new to multi-threaded programming. I am getting unexpected behavior when using the join method. Sometimes both the threads give the same result, sometimes only one result is displayed and ... |
I am confused uisng joins method in Threads
Could somebody please explain
I have read that the Parent Thread would wait for its
child Thread , until the child completes its operation
I ... |
I Want to execute a Certain Task to take only 1000 MS , if it exceeds , i dont want to continue with the task ,
i have used join for this ... |
I have 2 threads T1 and T2 ,both have different jobs so usually we prefer to accomplish this task by thread Joins.
But we can do this with out using join(). ... |
I wrote a simple code that uses multiple threads to calculate number of primes from 1 to N.
public static void main (String[] args) throws InterruptedException
{
Date start;
...
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I have checked different questions in this and in other forums, but I didn't find the solution to my problem.
I have an application which runs ffmpeg and exiftool processes. ... |
In main method a child thread gets started using java 1.5 executor service mechanism. How can i make main thread to wait until the child thread gets completed ?
public class MainClass ...
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When writing code like:
public class TestBasic {
public static void print(Object o){
System.out.println(o);
}
public ...
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I would like to check whether a certain thread has already been joined.
In the code below I have threads that finish at different times and I would like to check whether ... |
Seems to be that this method is takes in an array of threads, then determines if they have completed using InterruptedException, which seems plausible to me.
private static void waitUntilAllThreadsFinished(Thread[] threadArr) {
...
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I am writing a test case and need InterruptedExpection to be thrown in the try-catch block of calling join(). Any example?
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I have problem understanding the meaning of join in the following case:
Thread t1=new MyThread(1);
Thread t2=new MyThread(2);
t1.start();
t2.start();
t1.join();
t2.join();
the question is:
as I understand start calls the run method of the Thread. ... |
(Thread) A.join() - causes current thread to wait for the thread A to complete.
I supposed then that calling this.join() from the run method will cause thread to deadlock - that it ...
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Hi, You can use the join() method and its various overloaded methods to help you out. I have modified your program to incorporate the feature. Basically join will wait for a thread to die before continuing the work of the thread of origin ie the main thread. public class myThread extends Thread { String name; public myThread (String theName) { name ... |
The current thread (the one running the main method) will wait for the execution of t.method1() to finish in the thread labeled d and then continue with execution of the main. Since there is no more code in the main the application will return/end. Is that the kind of answer you were looking for here? Paul |
Hello All, I am having a problem where thread.join will crash javaw.exe while debugging under JBuilder 4 pro under NT4. I have searched everywhere I can think and can find nothing on this problem. public class JoinTester extends Thread { public void run() { System.out.println(" started"); for(int counter=0; counter<5; ++counter) { System.out.println(" Loop " + counter); try{ sleep(500); } catch(InterruptedException e) ... |
35. join() coderanch.comIn brief in thread a if u spawned a thread b and want that thread a should not terminate untill thread b (as u might be expecting some output from thread b to be used in a) u have to call b.join() in a ,,this join() will not return untill the thread on which it is called is terminated .. |
Normally, the JVM stops when all of your Threads have finished. But sometimes you need to create a Thread which performs some background service, indefinitely. When your main thread exits, you want the JVM to stop too, even though this background thread may still be running. By creating it as a daemon thread, you are telling the JVM that it should ... |
I'm to change someone elses code and having trouble understanding it. Runnable is used since the GeneralForm is extended by many classes. This is simplified excerpts. 5 Questions; 1-4 on THE CODE below, then 5 a further complication. Basically trying to decide if threads complete or whether other action on screen interrupts them (action before dialogs appear; or action on dialogs). ... |
Hi, I am dealing with threads. I have an ArrayList of threads which I am trying to stop. The run() method in the threads is a while loop.. i.e. while(isRunning){ do something } Now, I set this "isRunning" variable to false when I want to stop the thread. It exits the run method, but the thread is still alive. I use ... |
39. join() ? coderanch.comAccording to all that I've read join() should prevent a method from moving to the next line until the active thread returns. However, I just read an article which states that depending on the operating system two threads such as thread1.join() thread2.join(), where thread1 and thread2 access the same runnable object, could yeild unpredictable results. Can anyone clarify this for me ... |
i reckon join is used to when one thread waits for another to finish and then the former thread continues. say if i hav created 3 child threads out of my main thread . i give 3 join methods in my main so that it waits till all 3 child threads finish their task and then the main thread resumes. what ... |
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As of JDK 1.5, you can now use the goodies in java.util.concurrent. I use the following code to check that an Executor fails as expected when its queue is full. I do this by giving it too many requests, but I need to wait until all threads have completed before I check that an error occurred at some point. To do ... |
join() allows you to wait until one thread is done before another can continue. So, let's assume that Thread object test1 is the current thread of execution. If the following code is executed: Thread test2 = new Thread( someRunnable ) test2.start() try { test2.join(); } catch(InterruptedException e){} ...The test1 will have to wait until test2 is dead before it can continue ... |
ArrayList processorsList = new ArrayList( no_intfiles.intValue() ); for ( int x = 0; x |
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Dear Friends, i have written a simple program... class Join implements Runnable { public void run() { for(int i=0; i<5; i++) { System.out.print(Thread.currentThread().getName() + " : " + i + "..<>"); } System.out.println(); } } class JoinDemo { public static void main(String[] args) { Join justJoin = new Join(); try { Thread t1 = new Thread(justJoin,"One "); Thread t2 = new ... |
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred: Another thread notifies threads waiting on this object's monitor to wake up either through a call to the notify method or the notifyAll method. The timeout period, specified by timeout milliseconds plus nanos nanoseconds arguments, ... |
Please can someone explain me the output of the following code. Please explain how the code works to ensure the output behaviour... I 've tried hours to understand it but I cannot. The following code produces this output always : A.The number 14 is printed before number 22 B.The last number printed is 12. //==============CODE public class cc{ ArrayList arl = ... |
Originally posted by Sunil Palicha: What is the difference between wait and join ? One difference that I am aware of is wait needs to be used in synchronized method or block whereas join can come right after start(). Can join be used to act as wait ? If yes, under what conditions ? |
please help me in understanding this code... class JoinTest extends Thread { public static void main(String[] args) { JoinTest j1 = new JoinTest(); j1.setName("one"); j1.start(); System.out.println(j1.getName()+" : "+j1.isAlive()); try { j1.join(); }catch(InterruptedException e) { } System.out.println(j1.getName()+" : "+j1.isAlive()); //Showing false -- ie j1 thread has finished executing run()....ie j1 is dead j1.start(); // trying to restart j1 System.out.println(j1.getName()+" : "+j1.isAlive()); // ... |
I have been pointing out Sun's error in exposing its monitors. Specifically I have cited join() as a prime culprit. join() uses the 'this' object's monitor. There is another thing that occured to me today as I was writing some code. join creates a mutual synchronization boundary. Follow these few steps; 1. Thread A sets x to a value. 2. Thread ... |
If one Thread needs to wait for another to complete it job then you can make use of join() method. For eg. There are two threads Thread A and B. Thread A need to start it job after Thread B gets completed then mark the follwoing in Thread A b.join(); Thread A's stack will be added at the end of Thread ... |
Hi, I want to do this task and i have a problem. there is one array of constant length and many threads are trying to fill this array simultanously. Since this array is shared among these threads you need to apply synchronization in right region. After the array is filled completely the average of the array elements should be calculated and ... |
Welcome to the ranch! t.join() makes the current thread wait until t ends. The interrupt() call wakes t from sleep, and we want to make sure t exits its run() method before we do anything else. That should happen almost instantly, but we don't have any guarantees that our next statement won't run before that happens, so join() gives us that ... |
package test; public class JoinSample{ public static void main(String[] args) { System.out.println("Main started,"); Thread theThread = new AAA(); Thread theBThread=new BBB(); try { theThread.start(); theBThread.start(); if(theBThread.isAlive()) { System.out.println("Thread B Alive and I am in"); theBThread.join(); } } catch (Exception e) { e.printStackTrace(); } System.out.println("main ready."); } } class AAA extends Thread { public void run(){ try{ System.out.println("---------Thread AAA--------------Started"); for (int counter=0; ... |
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If you call join() on a thread, it won't return until that thread terminates. So what join() does is wait for a thread to complete. Imagine you want to start ten worker threads, then do something when all ten are finished. You'd create the ten threads, store them in an array, the start them all. Then you use a for loop ... |
/* All i need is to call in this program is the join method inside either class DivisionEven or DivisionOdd so that first DivisionEven executes(say) an then after its completion DivisionOdd executes...it definitely can be either way round but all i need is to know rather learn how to do it except in main */ package com.packages.multithreading; class DivisionEven implements Runnable ... |
hi all! class C extends Thread { private String name; private C c; public C(String name) { this.name = name; } public void setC(C c) { this.c = c; } public void run() { try { if (c != null) c.join(); } catch (Exception e) { } for (int i = 0; i < 10; i++) { try { sleep(1000); } ... |
Hi all, I have copied a code from Khalid A. Mughal on join(), and a bit confused about how the output came. the code is as followed /** * */ package threads; /** * @author Sandeep Mukherji * */ public class Joining { static Thread createThread(final int i, final Thread t1){ // function Thread t2 = new Thread(){ // thread created ... |
Originally posted by amitabh mehra: If you have a thread X, that you want, should only run after thread Z has completed its execution and entered the dead state, then you make thread X to "join" thread Z. So now, X will not be in runnable state till Z has finished. Hope this answered your question. When using states with respect ... |
In the Old Days, before the java.util.concurrent package was added to the API, a common use of join() was to know when a set of parallel tasks was completed. You'd create a group of threads to run some tasks in parallel, storing references to all the threads in an array. Then you loop over the array and start all the threads. ... |
Hi, Please clarify these doubts towards the following sample code: 1. How before completion of the instantiation of thread object, start() can be called? 2. If join() is uncommented, does main thread waits for Test119 thread or vice versa? 3. If start() is invoked/called before makeItSo() without join(), why makeItSo()completes first? 4. Suppose three threads are created t1, t2, t3 and ... |
join() is required when one thread T1 must do its job before thread T2 can complete its work. So in a way we want the threads to work sequentially, one after another. But this can also be done by putting the logic in two different methods and calling them sequentially. Then what is the use of join() ? Thanks, |
Calling join() on a thread (say T1) would keep the current thread waiting till the thread it joins (say T2) dies off. However, the current thread won't release any locks it has acquired while being in the wait state. So if T2 attempts to enter a method synchronized on some monitor,whose lock has already been acquired by T1,calling T2.join() through T1 ... |
Hi !! I understand muli-threading as "parallel instances of execution" and i have a query in this regard. The following is a code and its output. I would like to how will you describe "what exactly is the join() method doing here?". class NewThread implements Runnable{ String name; Thread t; NewThread(String threadname){ name = threadname; t = new Thread(this,name); ... |
From the source code: public final void join() throws InterruptedException { join(0); } public final synchronized void join(long millis) throws InterruptedException { long base = System.currentTimeMillis(); long now = 0; if (millis < 0) { throw new IllegalArgumentException("timeout value is negative"); } if (millis == 0) { while (isAlive()) { wait(0); } } else { while (isAlive()) { long delay = ... |
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As a general rule, you can use .join() on any thread, and this would include the ones available in a Web App. But Web Apps can be touchy things, and I would suggest only using it on Threads that you create manually, for example if you have a few background threads you create to process data, then want the container-generated request ... |
Following is the implementation of Thread.join(long millis). Calling newThread.join() leads to join(0) being called which in turn,as Henry said,causes the method to return,because isAlive() for a thread that has not been started would return false. public final synchronized void join(long millis) throws InterruptedException { long base = System.currentTimeMillis(); long now = 0; if (millis < 0) { throw new IllegalArgumentException("timeout value ... |
I am clear with the definition. But was having problem in writing small example which demonstrates how join() actually works. After posting this topic, I tried for a while and wrote a program which actually shows how join() works class Job_1 implements Runnable { public void run() { for(int x='z';x>='a';x--) System.out.println("\t\t\t"+Thread.currentThread().getName()+"-->"+(char)x); } } class Job_2 implements Runnable { public void run() ... |
I'm currently studying the Thread.join() method, and I'm not sure If I'm getting it right. Here is what I want. I have two objects which implements Runnable, ThreadA and ThreadB ThreadA has a static variable int x. This variable is given a value of 5 if the ThreadA is started. ThreadB displays the value of the static variable of ThreadA. But ... |
what does it mean to have this.join e.g. class MyThread extends Thread{ public void run(){ //something abc(); } public void abc(){ this.join(); //something } In general t.join would mean that in the current thread, let thread t complete (does complete here mean end run method or it could be block/etc) and then run the lines below t.join(). What would it mean ... |
Hi , I never used Java Threads explitly . So please let me know this one. Consider a thread T1 invokes the method join() on a thread T2. Is this mean that The Thread T1 will be coming under Runnable state only if when Thread2 has completed its operation (i mean its run method) |
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Hi, I read that when a thread calls join, it makes the currently running thread join after it. Please correct me if i am wrong here. Now what happens if innocently the thread that is currently running calls join()? I believe the scenario would roughly translate to "Thread.currentThread().join();" I tried this in eclipse out of curiosity and it seems to me ... |
The yield() method merely passes the hint to the underlying scheduler, that it wishes to give up on its current time slice. Whether anything happens, is dependent on the scheduler. With certain schedulers, this could mean that a lower priority thread will get a chance to run -- but if it does, it will unlikely run very long, before the scheduler ... |
import java.util.concurrent.BrokenBarrierException; import java.util.concurrent.CyclicBarrier; import java.util.logging.Level; import java.util.logging.Logger; public class Main { public static void main(String[] args) throws BrokenBarrierException, InterruptedException { CyclicBarrier cdl = new CyclicBarrier(5, new Runnable() { public void run() { System.out.println( " All Threads have completed Similar to Join"); } }); Workers[] workers = new Workers[5]; for (int i = 0; i < workers.length; i++) { workers[i] = ... |
Hi, Is it a bad idea to use setDaemon(true) and join() on the same thread? I am thinking this because the setDaemon will make the thread a low priority and the join() method waits for it to finish which may be a very long wait on a busy operating system. anyone have any experience or opiniions on this question? appreiciate any ... |
Hi, I have two different thread. One for getting data from database, another for getting data from file system. These two thread are independent of each other. Once both get completed, need to send mail which contains fetched data from database and filsystem as well. function call is as follows: public static void main(String[] a) { ..... ..... Thread thread1 = ... |
Hi savvy pals, Why does the following two codes making a difference. class ThreadTesting2 { public static void main(String... args) throws InterruptedException { Dog d= new Dog(); Thread t = new Thread(d,"Dog"); t.start(); t.join(); for(int i=1;i<50;i++) System.out.println(Thread.currentThread().getName() + " "+i); } } class Dog implements Runnable { public void run() { for(int i=1;i<50;i++) System.out.println(Thread.currentThread().getName() + " "+i); } } class ThreadTesting2 ... |
Hi, I'm using Executors.newFixedThreadPool to get a pool and manage my threads. I'd like to be able to "join" a thread that belongs to this pool. Is it possible? A solution I thought about, was to send an object to the Runnable constructor, and have the thhread that invokes the thread in the pool to "wait" in this object, have the ... |
We use join() whenever we need to attach a thread at the end of another thread. For eg. Suppose there are two threads : t1 and current thread(main thread) and we invoke start method on t1 and write t1.join(); This will join the current thread(main thread) at the end of thread t1. As soon as this statement is executed main thread ... |
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Hey ranchers! I have a situation where I call several WebServices that take long time to return. Threads came to mind. In some cases though I need the returned values right after the call. Does it make any sense to make a Thread, start it and then call join() straight away, waiting for results. Are there any benefits doing it this ... |
You don't need two threads for this. After all, One and Two don't need to be executed in parallel. Just create one Runnable. If for some reason you cannot or will not join the two classes in one you can wrap them: package test; public class Main { public static void main(String args[]) throws Exception { final One o = new ... |
Hi , What is the correct way to call join Method on a Thread or will it make any difference if Thread.join is made before starting the Threads. Assume that there are two Threads(Both extending Thread class) One and Two . One one = new One();// Consider One is a Thread that implements Runnable Two two = new Two();// Consider Two ... |
Hi , Thread join not working in this case , please help . I want Thread (Two ) to be executed first and then execute Thread One , but its not happening . Please help . class One extends Thread { public void run() { System.out.println("I Belong to ThrEAD oNE "); } public static void main(String args[]) throws Exception { One ... |
Hi, I ran the below code 10 times and it prints both the threads synchronously. How is that possible? join is in the main function whose purpose is to wait for both threads to finish before quiting main. class s5 { public static void main(String[] args) { Thread t1 = new Thread(new Spawn(),"John"); Thread t2 = new Thread(new Spawn(),"Thomas"); try { ... |
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public class ThreadDemo extends Thread { public void run() { for(int i = 0; i < 5; i++) compute(); } public static void main(String[] args) { ThreadDemo thread1 = new ThreadDemo(); Thread thread2 = new Thread(new Runnable() { public void run() { for(int i = 0; i < 5; i++) compute(); } }); if (args.length >= 1) thread1.setPriority(Integer.parseInt(args[0])); if (args.length >= ... |
Pasted below in the code for join method in Thread class. public final synchronized void join(long millis) throws InterruptedException { long base = System.currentTimeMillis(); long now = 0; if (millis < 0) { throw new IllegalArgumentException("timeout value is negative"); } if (millis == 0) { while (isAlive()) { wait(0); } } else { while (isAlive()) { long delay = millis - ... |
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Example: Say you have 75 mins of work and you work out that 25 mins and another 50 mins can be down in parallel (multithreaded) and the results combined so you start the 50 min job in parallel (another thread) , do your 25 min work (main thread) and join to wait for the 50 min job to complete. Total running ... |
I Want to execute a Certain Task to take only 1000 MS , if it exceeds , i dont want to continue with the task , i have used join for this . Please tell me and guide me if this is correct or not import java.util.List; public class MainThread { public static void main(String args[]) throws InterruptedException { Thread mainthread ... |
If I write t.join(),t is a thread, then it means that currently executing thread stops executing until the thread it joins with,in this case 't', completes. I want to know when t.join() is called, will the currently executing thread moves back to any blocking/waiting state or in runnable state? Also, is currently executing thread will sure to run once thread 't' ... |
I'm new at this, so take these recommendations with a grain of salt. First of all, I believe that join means to join the referenced thread up with the current thread. The way you have it, with threadA.join(); on the main thread means that the main thread should wait for the threadA to complete. I'm not clear on what you want ... |
import java.io.File; // PROBLEM... // Worst case it will wait two minutes if both files do not exist, // one minute if one or the other does not exist, but will typically // only take several seconds if everything is working. // Would line to wait a MAXIMUM of 1 minute for BOTH threads. public class TryExistsThread { public static void ... |
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