A ReentrantLock is unstructured, unlike synchronized constructs — i.e. you don’t need to use a block structure for locking and can even hold a lock across methods. An example: private ReentrantLock lock; public void foo() { … lock.lock(); … } public void bar() { … lock.unlock(); … } Such flow is impossible to represent via … Read more
Back in the old days of Python, to call a function with arbitrary arguments, you would use apply: apply(f,args,kwargs) apply still exists in Python2.7 though not in Python3, and is generally not used anymore. Nowadays, f(*args,**kwargs) is preferred. The multiprocessing.Pool modules tries to provide a similar interface. Pool.apply is like Python apply, except that the … Read more
Concurrent programming regards operations that appear to overlap and is primarily concerned with the complexity that arises due to non-deterministic control flow. The quantitative costs associated with concurrent programs are typically both throughput and latency. Concurrent programs are often IO bound but not always, e.g. concurrent garbage collectors are entirely on-CPU. The pedagogical example of … Read more
I want to make sure this is out there, because it’s so hard to get right: using System.Runtime.InteropServices; //GuidAttribute using System.Reflection; //Assembly using System.Threading; //Mutex using System.Security.AccessControl; //MutexAccessRule using System.Security.Principal; //SecurityIdentifier static void Main(string[] args) { // get application GUID as defined in AssemblyInfo.cs string appGuid = ((GuidAttribute)Assembly.GetExecutingAssembly(). GetCustomAttributes(typeof(GuidAttribute), false). GetValue(0)).Value.ToString(); // unique id for … Read more
Think of semaphores as bouncers at a nightclub. There are a dedicated number of people that are allowed in the club at once. If the club is full no one is allowed to enter, but as soon as one person leaves another person might enter. It’s simply a way to limit the number of consumers … Read more
Can anyone tell me the advantage of the synchronized method over the synchronized block with an example? Thanks. There is not a clear advantage of using synchronized method over the block. Perhaps the only one ( but I wouldn’t call it an advantage ) is you don’t need to include the object reference this. Method: … Read more
Basically on an ExecutorService you call shutdown() and then awaitTermination(): ExecutorService taskExecutor = Executors.newFixedThreadPool(4); while(…) { taskExecutor.execute(new MyTask()); } taskExecutor.shutdown(); try { taskExecutor.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS); } catch (InterruptedException e) { … }
Thread-safe code is code that will work even if many Threads are executing it simultaneously. http://mindprod.com/jgloss/threadsafe.html
There actually is a trick how to execute a parallel operation in a specific fork-join pool. If you execute it as a task in a fork-join pool, it stays there and does not use the common one. final int parallelism = 4; ForkJoinPool forkJoinPool = null; try { forkJoinPool = new ForkJoinPool(parallelism); final List<Integer> primes … Read more
GCD is a low-level C-based API that enables very simple use of a task-based concurrency model. NSOperation and NSOperationQueue are Objective-C classes that do a similar thing. NSOperation was introduced first, but as of 10.5 and iOS 2, NSOperationQueue and friends are internally implemented using GCD. In general, you should use the highest level of … Read more