Long time ago, I saved a sentence from a Java reference book: "Java has no mechanism to handle deadlock. it won't even know deadlock occurred." (Head First Java 2nd Edition, p.516)
So, ... |
First, here's a sample:
public class Deadlock {
static class Friend {
private final String name;
...
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The simple piece of midlet code (class Moo) below (after the excerpts) deadlocks (At least I assume it deadlocks after reading this post on threads here).
I have reproduced ... |
I have a basic question. Why and how SelectableChannel's register method can be in blocking call.
Let me provide a scenario.
I have created a Selector object in class Register as ... |
suggest me any real time situations in which i'm supposed to create multiple threads,and then introduce a deadlock situation.this is kind of a project!!! can u ppl help to make the ... |
can anyone post a java code that ends up in deadlock??
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I'm doing some excercises with java (some of you may suppose where the code comes from). I try to provocate a deadlocksituation with the following code:
class Resource {
...
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I am looking for a tool which can predict deadlocks in java before the occur.
I tried to use MTrat but failed (maybe it does not supports Sun Hotspot JVM so ... |
I have a requirement to manipulate two queues atomically and am not sure what is the correct synchronization strategy: This is what I was trying:
public class transfer {
...
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want to know what is deadlock condition in threads, because in many of the books i studied how to avoid deadlock situation, i just want to know what is deadlock situation ... |
I found following post http://stackoverflow.com/questions/370710/java-6-jvm-hang with somewhat similar exception that am getting. There is no deadlock. But many threads are in WAIT state. Stack trace is as follows. My Client ... |
I have a process that is supposed to ftp a file to a remote location every 5 minutes.
It seems to have become stuck for a number of hours and hasn't been ... |
This code will deadlock:
public class Main {
static public final Object a = new Object();
static {
Runtime.getRuntime().addShutdownHook(new Thread() {
...
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Below is code directly from the Sun tutorials describing Deadlock. I however don't understand how Deadlock can occur in this situation considering both methods are synchronized. How would two ... |
I have 2 threads. One thread prints odd numbers and the second thread prints even numbers. Now, I have to execute the threads alternatively so that i can output 1,2,3,4,5,6,.....
I ... |
I'm chasing a production bug that's intermittent enough to be a real bastich to diagnose properly but frequent enough to be a legitimate nuisance for our customers. While I'm waiting ... |
I am having some troubles to understand how I have to stop a running thread. I'll try to explain it by example. Assume the following class:
public class MyThread extends Thread {
...
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I'm working on some application and using ThreadPoolExecutor for handling various tasks. ThreadPoolExecutor is getting stuck after some duration. To simulate this in a simpler environment, I've written a simple code ... |
can anyone explain me why there is a deadlock in this code.Thanks
public class Deadlock {
static class Friend {
private final ...
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Is it technically possible for a thread in Java to deadlock itself?
I was asked this at an interview a while back and responded that it wasn't possible but the interviewer told ... |
I have the following problem. My J2ME app goes totally dead. I though it was a deadlock, but using NetBeans' built-in functionality, it couldn't find such.
After some time however, it started ... |
I have a multithreaded application. Several messages are coming to the application and are processed in separated threads. For this I am using classes ThreadPoolExecutor and FutureTask from package java.util.concurrent.
Occasionally I ... |
I am having an issue with some process wrapping, and it's only occurring in Windows XP. This code works perfectly in Windows 7. I'm really stumped as to why ... |
Read that deadlock can happen in a single threaded java program. I am wondering how since there won't be any competition after all. As far as I can remember, books illustrate ... |
This question was asked in an interview and the approach taken architecturally to solve this problem at high level was being judged. In Java, how can this be solved
-->N threads .. ... |
I'm trying to work with JavaSound. I have an example program (eg. http://www.jsresources.org/examples/SimpleAudioPlayer.java.html) that works on one of my machines, but not on the other (Both Linux). ... |
The purpose of the following code is to implement a LIFO container just like a Stack, while, when retrieve an element, it will check if there is any existing element in ... |
I saw the below statement in Java Specifications.
Programs where threads hold (directly
or indirectly) locks on multiple
objects should use conventional
techniques for deadlock avoidance,
... |
I am reading Java Concurrency in Practice and got stuck on this program,where author say it won't cause the deadlock. But if I swap the method arguments then it will cause ... |
Usually for thread safety, we access the field using synchronized(lock).
If without using synchronized(lock) and access the field directly, can we encounter deadlock in some case?
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I have a problem, i cannot resolve this problem
void Transfer(Account a, Account b, decimal amount)
{
lock (a) {
...
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I create a pool of threads with an Executors.newFixedThreadPool, but after a time I noticed that some of them stoped to answer (call this method below).
They was destroyed? I doing synchonization ... |
I wonder whether it is possible to detect deadlocks dynamically in Java by using the JVMTI. There are two events indicating actions on monitors using the synchronized statement:
Monitor Contended Enter
... |
We have a webapp designed with multiple JMS listeners. Castor is used as XML-JAVA binding.
More often than not we run inton deadlocks, which when we dequeue the messages, restart the applserver ... |
I've got a deadlock in my application, but there is no obvious locking instance in the stack trace. How is this possible? Is this a bug?
jstack -l output
Full thread dump OpenJDK ...
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I have the following Java code:
import java.util.concurrent.*;
class Foo{
static Semaphore s = new Semaphore(1);
public void fun(final char c, final int r){
...
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I'm writing an an applet and it sometimes hangs before it even enters init() when running under Chrome (14.0.835.202 m) on Windows 7 64.
I'm using the following bit of code to ... |
Yes this code has a race condition. Even if you run something a thousand times and there is no problem, that doesn't mean it will work the thousand and oneth. One of the fundemental rules of locking is that threads should always get locks in the same order. This code gets them in diffrent orders. |
Well, if "destroyed" means destroy() is called, and "suspended" means suspend() is called, then the answers are rather different in those two cases; and there are other possible definitions of "died" as well, each with different meaning (stop(), wait(), sleep(), throwing a RuntimeException) If he wants an answer to one particular case, then I'll be glad to provide it; but if ... |
deadlock is a situation which occurs when two or more threads are waiting to gain control of a resource,Due to some reason the condition on which waiting threads rely on to gain control doesnot happen. eg. thread A must acess method1 before it can release Method2,but ThreadB cannot release Method1 until it gets hold of method2 Thread A synchronized method2() { ... |
A typical deadlock occurs where two threads do something like: I lock A and wait for B You lock B and wait for A We both wait forever One prevention guideline is: If you're going to lock two or more objects, always lock them in the same order. This is tough if you don't own all the code or if developers ... |
Hi stan, Deadlock occurs when two (or more) threads hold a lock that the others need to complete. e.g. Thread A holds a lock on object 1 and needs a lock on object 2 to complete. Thread B holds a lock on object 2 and needs a lock on object 1 to complete. Your code starts two Threads (incidentaly the name ... |
Hi all, try to get a deadlock accessing via 2 threads 2 resources in synchronized blocks like: synchronized(A){ synchronized(B){ } } and synchronized(B){ synchronized(A){ } } i try to put the threads on sleep, use system.outs just to make sure my threads are accessing these objects in a convenient way, i know this because i got this output(copied/pasted from one run): ... |
Deadlocks are always, at the base of it, caused by different threads locking sets of objects in different orders. Is anyone aware of any tool which can do a sort of "static deadlock analysis" of a library? By this, I mean examine trajectories though possible call stacks, and find cases where locks are acquired in varying orders. You can simply run ... |
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46. deadlock coderanch.comclass MainStone { public static void main(String[] args) { System.out.println("Hello World!"); Flintstone fs=new Flintstone(); fs.fred(1); } } class Flintstone { int field_1; private Object lock_1 = new int[1]; int field_2; private Object lock_2 = new int[1]; public void fred( int value ) { synchronized( lock_1 ) { synchronized( lock_2 ) { this.barney(1); try { Thread.sleep(5000); } catch(Exception e){e.printStackTrace();} System.out.println("fred"); field_1 = ... |
What are the practices to be followed for avoiding deadlocks? Deadlock can arise if four conditions hold simultaneously, so you can check these conditions with your program carefully. Mutual exclusion: only one process can use a resource at a time Hold and wait: a process holding at least one resource and also is waiting to acquire additional resources held by another's ... |
Could you give me a hint how to make threads running the viewpanel/Header.fireResizEvent() synchronized? I tried to put the synchronized keyword to the lotus/notes/apps/viewpanel/Header.setWidth method, is it correct? Synchronization is *not* a silver bullet that can solve your deadlock problems. In fact, it was probably synchronization that caused it in the first place. You really need to know what you are ... |
49. Deadlock coderanch.comThere's no universal way to avoid deadlock for any given program. The way to prevent it is to design your application correctly. You'd be better off reading the large number of papers on the subject that you can find through any search engine. As this is a very complex subject, any answer here is going to be cursory at best. |
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - ... |
I dont think you can use the same tools to prevent dead lock of ur thread with a process in OS. The tools you use are the same, even though they have a different nomenclature. We use mutexes (the equivalent of an object lock) and semaphores (which are basically just fancy mutexes) to synchronize the use of resources, and shared memories ... |
52. deadlock coderanch.comHi Imagine a situation: We have two threads t1 and t2 and two resources r1 and r2. Suppose t1 holds r1(for its own use) and t2 holds r2, with this assume that t1 needs r2 for its completion and t2 needs r1 for its completion and they both can't proceed without the needed resources. Obviously t1 can't release r1 and t2 ... |
I don't understand why the subject line of this message mentions "deadlock" -- the question seems unrelated to this. Thread.currentThread() returns a Thread object, the currently executing Thread. "this" refers to the object whose method is being called. "this" and currentThread() will only return the same thing in the relatively rare circumstance that you've subclassed Thread and the code being executed ... |
If you make create() synchronized, you'll fix the deadlock situation. Deadlocks happen when multiple threads are all trying to lock the same two objects, but they try to lock them in a different order. In your code, the create() method locks "list", and then locks A.class (via the call to the static callCount() method.) On the other hand, the remove() method ... |
Friends, I am looking at an application, which hangs after a while. We have taken a thread dump, and I am trying to analyze the problem. Unfortunately, I could not figure out very much out of the dump as my skills are a little inferior at the moment. But one thing that looks like causing the problem is the following thread ... |
Bob, do you mean that all requests to the database are only queries (no updates, no transactions) or that you have, say one thread doing only queries and another thread which can do updates and transactions? If you have page level locking on the database then you can still have deadlocks in the latter case - one thread only doing queries ... |
57. deadlock coderanch.comSome (all?) deadlocks occur when two threads try to lock the same resources in different sequence. Thread 1 locks A and tries to acquire B while thread 2 locks B and tries to acquire A. So one solution is to always acquire multiple locks in the same order. That's hard to enforce across a system, though. I remember reading about a ... |
58. DeadLock coderanch.comHi all, The Q is, If deadlock occurs how to remove deadlock or overcome deadlock? That is I use simple thread programming in code and not use synchronise the threads.But deadlock occured.Then I want to remove deadlock then I want to write as synchronized , but before I was not aware that deadlock will occur.So how to overcome....? ['If u say ... |
I have methoed that is call from many difrent portlets: /** * @return Returns the pcUniqueName. */ public static int getPcUniqueName() { pcUniqueName++; return pcUniqueName; } The pcUniqueName is a class member defined as: static int pcUniqueName; I need a unique number in the JVM, this is called from many difrent portlets at the same time.... Can this give deadlock in ... |
All the three threads have been synchronized on the String object "as" which is a part of the class containg Main. This has been done to achieve a sequential invokation of the threads in order they were started , no matter how much time each takes. This works fine with notify , but notifyAll causes all the threads to wake up ... |
This is a generic question. So I'll give search tips rather than try answering that. You HAVE to understand what threads are, what monitors are, and what wait and notify methods really do. You could start here JavaWorld Article: Synchronizing Threads In Java which is probably one of the few articles that has any mention of a "potential monitor" to an ... |
Hello everybody? I wrote a test program for my employer. But developers there said that it is wrong and cause a deadlock. Please, comment if it is so or not? The task is that there is N producers and M consumers. One generates integers and another print it to console. My code is below: ==Producer.java== import java.util.Random; /** * Producer produces ... |
What's the best way to detect deadlock and remove deadlock? Example: public class RunDeadLock { public static void main(String[] args) { Thread1 t1= new Thread1(); Thread2 t2= new Thread2(); t1.start(); t2.start(); } } public class Thread1 extends Thread { public void run(){ ThreadResource1.go1(); } } public class Thread2 extends Thread { public void run(){ ThreadResource2.go2(); } } public class ThreadResource2 { ... |
public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s has bowed to me!%n", this.name, bower.getName()); bower.bowBack(this); } public synchronized void bowBack(Friend bower) { System.out.format("%s: %s has bowed back to me!%n", this.name, bower.getName()); } } public ... |
Found one Java-level deadlock: ============================= "Thread-18": waiting to lock monitor 0022f384 (object 65802a98, a sun.misc.Launcher$AppClassLoader), which is held by "Thread-14" "Thread-14": waiting to lock monitor 00d5ced4 (object 65803080, a sun.misc.Launcher$ExtClassLoader), which is held by "Thread-18" Java stack information for the threads listed above: =================================================== "Thread-18": at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:260) - waiting to lock <65802a98> (a sun.misc.Launcher$AppClassLoader) at java.lang.ClassLoader.loadClass(ClassLoader.java:235) at java.security.Provider.loadProvider(Provider.java:149) at java.security.Security$3.run(Security.java:350) at ... |
Hi All, I've got the thread log below. In your opinion is the following situation deadlock, or is it just starvation? Thank you very much for your reply, Roman "AJPRequestHandler-ApplicationServerThread-1" prio=5 Thread id=1 BLOCKED com.mycompany.project.util.MySessionLog.log(MySessionLog.java:32) oracle.toplink.publicinterface.Session.log(Session.java:2221) oracle.toplink.publicinterface.Session.log(Session.java:3495) oracle.toplink.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:485) oracle.toplink.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:442) oracle.toplink.threetier.ServerSession.executeCall(ServerSession.java:453) oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:117) oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:103) oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeSelectCall(DatasourceCallQueryMechanism.java:174) oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeSelect(DatasourceCallQueryMechanism.java:156) oracle.toplink.queryframework.DirectReadQuery.executeNonCursor(DirectReadQuery.java:92) oracle.toplink.queryframework.DataReadQuery.executeDatabaseQuery(DataReadQuery.java:110) oracle.toplink.queryframework.ValueReadQuery.executeDatabaseQuery(ValueReadQuery.java:55) oracle.toplink.queryframework.DatabaseQuery.execute(DatabaseQuery.java:603) oracle.toplink.queryframework.DataReadQuery.execute(DataReadQuery.java:96) oracle.toplink.publicinterface.Session.internalExecuteQuery(Session.java:2062) oracle.toplink.publicinterface.Session.executeQuery(Session.java:981) oracle.toplink.publicinterface.Session.executeQuery(Session.java:938) oracle.toplink.sequencing.QuerySequence.select(QuerySequence.java:264) oracle.toplink.sequencing.QuerySequence.updateAndSelectSequence(QuerySequence.java:215) oracle.toplink.sequencing.StandardSequence.getGeneratedVector(StandardSequence.java:58) oracle.toplink.sequencing.DefaultSequence.getGeneratedVector(DefaultSequence.java:121) oracle.toplink.sequencing.Sequence.getGeneratedVector(Sequence.java:229) oracle.toplink.internal.sequencing.SequencingManager$Preallocation_NoTransaction_State.getNextValue(SequencingManager.java:510) oracle.toplink.internal.sequencing.SequencingManager.getNextValue(SequencingManager.java:864) oracle.toplink.internal.sequencing.ClientSessionSequencing.getNextValue(ClientSessionSequencing.java:75) oracle.toplink.internal.descriptors.ObjectBuilder.assignSequenceNumber(ObjectBuilder.java:201) ... |
Hello class Reentrant { public synchronized void a() { b(); System.out.println("here I am, in a()"); } public synchronized void b() { System.out.println("here I am, in b()"); } } In the above code, the synchronized method a(), when executed, obtains a lock on it's own object. It then calls synchronized method b() which also needs to acquire a lock on it's own ... |
That article is certainly comprehensive, but not a quick read. To me, "deadlock" in Java normally means deadlock of thread synchronisation. This typically happens when more than one lock is involved in some operations and different threads lock the locks in different orders. The solution to this problem is to impose a synchronisation strategy on your code, so that locks are ... |
We are consistently hitting Deadlock with implementation of ThreadPoolExecutor We are creating a ThreadPool using the newCachedThreadPool() myThreadPool = Executors.newCachedThreadPool(); // Execute this folder in a seperate thread. myThreadPool.execute( new MyRunnable(buddy,nice) ); The problem we're currently running in to is that when one of the threads, in the threadpool is stuck... the other threads are stuck . And this is what ... |
I assume, Thread-A has acquired the lock on Object-1 and Thread-B has acquired the lock on Object-2. At the same time, Thread-B is trying to acquire the lock on Object-1 which is already owned by Thread-A. Similarly Thread-A is trying to acquire the lock on Object-2 which is already owned by Thread-B. The above case may lead to Deadlock situation. I ... |
class Shared { synchronized void test1(Shared s) { System.out.println("test1 started !"); try { Thread.sleep(100); } catch (InterruptedException e1) { System.out.println(e1); } [B]s.test2(this); [/B] System.out.println("test1 ends !"); } synchronized void test2(Shared s) { System.out.println("test2 started !"); try { Thread.sleep(100); } catch (InterruptedException e2) { System.out.println(e2); } [B]s.test1(this);[/B] System.out.println("test2 ends !"); } } class Thread1 extends Thread { Shared s1, s2; Thread1(Shared s1, ... |
I'm trying to prove to somoene that you can't have a deadlock on a JDBC Query. Could somoene help me in proving him wrong. As long as you close your connections carefully and dont use transaction than you should not have deadlock. I need arguments to be able to explain to him, thanks for your feedback. |
Hi all, we are experiencing a strange problem while running out application under Windows XP with Java 1.6. Our GUI swing application suddenly halts and stops responding to any keyboard/mouse actions. This happens mostly on startup (extensive net I/O and swing components initialization) during 3-5% of launches. The problem is that halted JVM doesn't respond to any debugging commands: jstack utility ... |
I am curious what would happen when you have an infinite loop or deadlock in finalize(). My guess is that the daemon GC thread will get hung up and as time goes on, heap space runs out which leads to OutOfMemory exception. Any thoughts or more accurate knowledge on this? Thanks Victor |
Short answer: a deadlock occurs when one thread has the monitor for A and tries to get the monitor for B while another thread has the monitor for B and tries to get the monitor for A. Each will wait forever for the other to give up a lock. So one trick is to always access resources in the same order. ... |
Hi all, try to get a deadlock accessing via 2 threads 2 resources in synchronized blocks like: synchronized(A){ synchronized(B){ } } and synchronized(B){ synchronized(A){ } } i try to put the threads on sleep, use system.outs just to make sure my threads are accessing these objects in a convenient way, i know this because i got this output(copied/pasted from one run): ... |
I have to create a dead lock in the following code that has two worker threads that carry out the addition. my assignment says it can be done by adding one line of code. i was able to do it by changing the order of arguments(In w2 i changed it from s,a to a,s) Worker w1 = new Worker (s,a); Worker ... |
hi, i am trying to do networking with the help of HttpConnection class but always get this warning either i use thread or not.. Warning: To avoid potential deadlock, operations that may block, such as networking, should be performed in a different thread than the commandAction() handler. and after this the MIDP application is not working. this is my code & ... |
79. deadlock coderanch.comPlease explain the deadlock here. 1. public class DeadlockRisk { 2. private static class Resource { 3. public int value; 4. } 5. private Resource resourceA = new Resource(); 6. private Resource resourceB = new Resource(); 7. public int read() { 8. synchronized(resourceA) { // May deadlock here 9. synchronized(resourceB) { 10. return resourceB.value + resourceA.value; 11. } 12. } 13. ... |
Hi Chenna, 1) Deadlock refers to a specific condition when two or more processes are each waiting for each other to release a resource, or more than two processes are waiting for resources in a circular chain. Its a concept not limited to Java. 2) There are various algorithms which could be used to avoid this eg: Banker's Algorithm. In Java ... |
Hi Below is a code where I get a deadlock. I need a solution to overcome this deadlock first with wait and notify and secondly with Semaphore. Can someone change the below code so that it runs without a deadlock. class X { private X otherX; public void setPartner(X otherX) { this.otherX = otherX; } public synchronized void m1() { System.out.println("It's ... |
I have written the code on thread as follows, package javapractise.threads; public class Ex03_10_DEC_09 implements Runnable { static int i = 0; public Thread t1=null; public Thread t2=null; @Override public void run (){ try{ for(int j=0;j<10;j++){ System.out.println(Thread.currentThread().getName()+" THREAD IN EXCECUTION "+i); i++; Thread.sleep(1000); t2.join(); } }catch(Exception e){ System.out.println(e); } } public static void main (String [] args){ Ex03_10_DEC_09 ex03 = new ... |
Hi, I had decalred a variable of type HashMap using a static keyword.inside a singleton. public class MySingletonClass { private static HashMap metaInfoXML = null; public init() { //the hashMap is intialized and filled up in this method, // NOTE, this is invoked only once in the application lifecycle (ie. during intialization) // and so the put() funtion on this ... |
84. Deadlock coderanch.comHi, Why not use the one from Sun's tutorial: Deadlock Example? Compile and and run the program. After the following two messages appear: "Alphonse: Gaston has bowed to me!" "Gaston: Alphonse has bowed to me!", press the following key sequence in the cmd/shell: - CTRL + break (Win) - CTRL + '\' (Unix) You'll receive a thread dump. Following is just ... |
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I have 2 threads. One thread prints odd numbers and the second thread prints even numbers. Now, I have to execute the threads alternatively so that i can output 1,2,3,4,5,6,..... I have written a program for this and this is resulting in a deadlock. The output is also not desired. When i run the program i get 1 2 4 3 ... |
87. deadlock coderanch.comHi! // An example of deadlock. class A { synchronized void foo(B b) { String name = Thread.currentThread().getName(); System.out.println(name + " entered A.foo"); try { Thread.sleep(1000); } catch(Exception e) { System.out.println("A Interrupted"); } System.out.println(name + " trying to call B.last()"); b.last(); } synchronized void last() { System.out.println("Inside A.last"); } } class B { synchronized void bar(A a) { String name = ... |
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Hi All, what does Java-level deadlock means, and what is the cause of this? I have problem with java deadlock. Can someone explain me why and what is the cause? "Thread-3" daemon prio=10 tid=0x0000002b12832000 nid=0x6868 waiting on condition [0x0000000041082000] java.lang.Thread.State: WAITING (parking) at sun.misc.Unsafe.park(Native Method) - parking to wait for <0x0000002abb4f0778> (a java.util.concurrent.locks.ReentrantLock$NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:747) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:778) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1114) ... |
The link and wiki gives information on necessary condition, prevention, avoidance and detection. My question what to do after deadlock is dectected. I have come across some articles which say that ThreadMxBean can be used to detect the deadlock threads. What I am trying to find out is there a way to move the threads in deadlock out of deadlock state ... |
Following is a dead lock scenario public class TreeNode { TreeNode parent = null; List children = new ArrayList(); public synchronized void addChild(TreeNode child){ if(!this.children.contains(child)) { this.children.add(child); child.setParentOnly(this); } } public synchronized void addChildOnly(TreeNode child){ if(!this.children.contains(child){ this.children.add(child); } } public synchronized void setParent(TreeNode parent){ this.parent = parent; parent.addChildOnly(this); } public synchronized void setParentOnly(TreeNode parent){ this.parent = parent; } } if the ... |
Here is working code. Please suggest ways to ensure deadlock or increase the probability of deadlocking : public class Hug implements Runnable { static Thread t1; static Hold h, h2; public void run() { if(Thread.currentThread().getId() == t1.getId()) h.adjust(); else h2.view(); } public static void main(String[] args) { h = new Hold(); h2 = new Hold(); t1 = new Thread(new Hug()); t1.start(); ... |
Strictly speaking, the chance of deadlock goes up if you use more locks, yes. However, you make it sound like you have a choice. There is no choice. If your program is multi-threaded, you need to use locks in those critical sections to guarantee that your program will run correctly. If you can reduce the number of locks in your program ... |
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Hello Friends, I am learning java now.I know the following program has deadlock, now i trying the avoid the deadlock for this program so please post your some suggestions how to avoid the deadlock for the below. class A { synchronized void foo(B b) { System.out.println(Thread.currentThread().getName( )+" Entered into A.foo()"); try { Thread.sleep(1000); } catch (InterruptedException e) { System.out.println("A Caught Exception"); ... |
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Hi all, I have two different sychronized methods which can be called at the same instant by different worker threads. I have same variables being accessed in both these sychronized methods. so would it create a deadlock as: 1st thread could have a lock on ABC, goes to case 1 and increments "a" and have to wait for "b" as 2nd ... |
99. DeadLock forums.oracle.comBut I have couple of questions: 1) Here we see 2 instances of class Friend - alphonse & gaston. He created 2 instances of Thread class.For the first thread, he created an instance of Thread with run() method and called alphonse.bow(gaston) object to start. My question is since the method bow is synchronized, first thread calls the bow method and processes ... |
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