locks

I am always very hesitant to bring my locks in the open, to make them public. I always try to keep the locks restricted to my implementation. Not doing that, is a recipe for deadlocks, I believe. I have the following class: class SomeClass { protected ArrayList<Listener> mListeners = new ArrayList<Listener>(); protected void addListener(Listener listener) { synchronized (mListeners) { mListeners.add(listener); } } protected void removeListener(Listener listener) { synchronized (mListeners) { mListeners.remove(listener); } } ... } When SomeClass wants to notify his listeners, would you do:

I have a LockManager that manages the locks of several threads. Sometimes the threads are bad boys, and I have to kill them and ask the LockManager to release all their locks. However, since I use ReentrantLock in java this is impossible, I can not unlock a lock owned by another thread. I am forced to use Locks (cannot use semaphores, it is point of the homework). Is there any Java Lock implementation that allows me to unlock locks owned by other threads? So far the options I considered are: re-implementing ReentrantLock in a way that allows me to do this Make some sort of mapping between

I'm wondering if there's a package or model that will help me solve this scenario. Let's say I have 3 threads and a bunch of objects A,B,C,D,E,F T1 needs locks A,B T2 needs locks B,C,D T3 needs locks E,F In this scenario, it'd be ok if T1 & T3 ran simultaneously. Also, T2 & T3 can run simultaneously. But T1 & T2 should never run simultaneously. Also, note that Threads can obtain an arbitrary number of locks, not just 2. (I saw an elegant solution to this problem with a fixed number of locks but not sure I can apply it here.) Obviously, I'd like each thread to acquire all the needed locks at

MySQL is adding more tools to monitor its internals with every new release, but one thing it still lacks is a way to find out who is locking what, and therefore which transactions block which other ones. This is such a vital feature that I ’ m considering writing my own patch to the source! Still, it is possible, to a limited extent, to find out who ’ s locking resources. In this article I ’ ll explain how you can do that. This article is the second in a series on how to use the innotop MySQL and InnoDB monitor. Introduction Here ’ s the situation: you are trying to update a table and every

This question is based on Synchronizing on an Integer results in NullPointerException and originated from this question Synchronizing on an Integer value I wanted to know what is the best way to increase number of locks in Java. Other than which is implemented in ConcurrentHashMap i.e. Based on Fixed array and by calculating hash of key to refer index of array? Below is what is expected. If doMoreThing() for one object is in process then I should not do doAnotherThing() for the same object if it called from different thread. public void doSomething(int i) { doAnotherThing(i);// some checks

尝试获取锁，如果获取到了执行同步的地方，如果获取不到那么返回的是false将做其他的事情。 public class TestTryLcok implements Runnable{ private static Lock locks = new ReentrantLock(); @Override public void run() { try { if(locks.tryLock(4, TimeUnit.SECONDS)){ System.out.println(Thread.currentThread().getName()+"-->"); Thread.sleep(6000); }else{ System.out.println(Thread.currentThread().getName()+" time out "); } } catch (InterruptedException e) { // e.printStackTrace(); }finally { locks.unlock();//会抛出锁对象的异常，因为没有获取锁在unlock的时候出异常，可以先判断一下是否存在在执行。 } } public static void main(String[] args) throws InterruptedException { TestTryLcok test

Lets say I am implementing a critical section and protecting some array in VC++, how do I do it using locks in VC++? You need the API functions for critical sections : InitializeCriticalSection Call once, from any thread, but typically the main thread, to initialize the lock. Initialize before you do anything else with it. EnterCriticalSection Call from any thread to acquire the lock. If another thread has the lock, it will block until it can acquire the lock. Critical sections are re-entrant meaning a thread successfully acquires the lock even if it already holds it. LeaveCriticalSection