synchronization

问题 The msdn article Thread Synchronization (C# Programming Guide) specifies that: lock (x) { DoSomething(); } is equivalent to: System.Object obj = (System.Object)x; System.Threading.Monitor.Enter(obj); try { DoSomething(); } finally { System.Threading.Monitor.Exit(obj); } and then that: "Using the lock keyword is generally preferred over using the Monitor class directly, ... because lock insures that the underlying monitor is released, even if the protected code throws an exception " Does this

问题 I was wondering if a call to Threa.Sleep on a thread that already acquiered a Monitor will release the lock before going to sleep: object o = new object(); Montior.Enter(o); Thread.Sleep(1000); Monitor.Exit(o); While the thread is suspended - can other thread acquire o ? 回答1: No, the lock will not be released if you Sleep. If you want to release it, use Monitor.Wait(o, timeout) ; further, you can also use this to signal from another thread - another thread can use Monitor.Pulse[All] (while

问题 I have two clients A and B. Both clients have identical, synced local data caches. If client A makes an offline edit to record X and then client B also offline edits record X and syncs with the server, when client A syncs with the server, the change that client B made is not reflected and no amount of bidirectional syncing makes the two clients correctly synced with the server. Other than this, my sync app works great for deletions, additions edits etc. It's only simultaneous offline edits

问题 I have an ugly race condition with a WPF usercontrol, which is some kind of extended ComboBox: The UserControl mainly defines two bindable DependencyProperties, one is the selected item, another one is a list, from which the selected item can be chosen. Both are bindable, so the control may be initialized with or without a selected item and both properties can be changed via binding (on DataContext change), further the selection may change due to user interaction. The UserControl contains a

问题 I read that mutex and binary semaphore are different in only one aspect, in the case of mutex the locking thread has to unlock, but in semaphore the locking and unlocking thread can be different? Which one is more efficient? 回答1: Assuming you know the basic differences between a sempahore and mutex : For fast, simple synchronization, use a critical section. To synchronize threads across process boundaries, use mutexes. To synchronize access to limited resources, use a semaphore. Apart from

问题 Could anyone explain what is the difference between these examples? Example # 1. public class Main { private Object lock = new Object(); private MyClass myClass = new MyClass(); public void testMethod() { // TODO Auto-generated method stub synchronized (myClass) { // TODO: modify myClass variable } } } Example # 2. package com.test; public class Main { private MyClass myClass = new MyClass(); private Object lock = new Object(); public void testMethod() { // TODO Auto-generated method stub

问题 In an effort to learn about synchronization via Java, I'm just messing around with some simple things like creating a counter shared between threads. The problem I've run into is that I can't figure out how to print the counter sequentially 100% of the time. int counterValue = this.counter.incrementAndGet(); System.out.println(this.threadName + ": " + counterValue); The above increments the AtomicInteger counter , gets the new value, and prints it to the console identified by the thread name

问题 I've painted my self into a problem working with a Subversion project from CodePlex - for this I asked for help here. I have a local repository and CodePlex has it's Internet repository for the project, and the two don't mix :-(. But my dear departed dad used to tell me that the difference between a clever man and a wise man is that the wise man does not enter the trap a clever man find his way out of. In other words: I must have been doing something wrong. So: Say you're a group of a few

问题 In the following code example, program execution never ends. It creates a thread which waits for a global bool to be set to true before terminating. There is only one writer and one reader. I believe that the only situation that allows the loop to continue running is if the bool variable is false. How is it possible that the bool variable ends up in an inconsistent state with just one writer ? #include <iostream> #include <pthread.h> #include <unistd.h> bool done = false; void * threadfunc1

问题 I am declaring a Java Map as Map<String, String> map = Collections.synchronizedMap(new HashMap<String, String>()); to deal with the concurrency issues, and synchronizing on the map for all the operations on it. However, I read that synchronization isn't necessary on a synchronizedMap when the operations are atomic. I checked the Java API and the documentation of HashMap doesn't seem to mention which are atomic, so I'm not sure which are. I'm synchronizing on the following calls to the map: