If (UnLockTest.a1.tryAcquire(1, TimeUnit. Public static final Semaphore a2 = new Semaphore(1) Public static final Semaphore a1 = new Semaphore(1) The case can not obtain, the general is to repeat the attempt, or specify the number of attempts, you can exit immediately. The semaphore can specify a timeout to get, we can according to the time-out, do an extra treatment. Semaphore can control how many threads can access resources, we specify here can only be one thread access, you do a similar lock. deadlock Star Here are 38 public repositories matching this topic. To solve this problem, we do not use to display the locks, we use semaphores to control. (new Date().toString() + " LockB 锁住 obj1") (new Date().toString() + " LockB 锁住 obj2") (new Date().toString() + " LockA 锁住 obj2") (new Date().toString() + " LockA 锁住 obj1") If improper use of locks, and the screen at the same time when you want to lock multiple objects, there will be a deadlock situation, as follows: Solution to the deadlock problem is: one is synchronized, one is to use explicit locks for Lock. Use the following code to simulate what java deadlock produce. Of course, if the case of a deadlock to break any of these conditions, you can let the deadlock disappear. When these four conditions are fulfilled, then a deadlock. 4, wait cycle, i.e., there is a queue: P1 P2 occupies resources, P2 and P3 resources possession, the P1 P3 share of resources.3, requests, and maintaining that when the resource requestor while requesting additional resources to maintain possession of the original resource.2, can not seize the resource requester can not be forced to seize resources from the hands of possession of resources, resources, resources can only be released by the initiative occupants.1, exclusive use, that is, when the resource is a thread (possession), other threads can not be used. Since the thread is blocked indefinitely, so the program can not be terminated normally. We should avoid this condition as much as we can. Deadlock condition can break our code at run time and can destroy business logic. Deadlock condition is a complex condition which occurs only in case of multiple threads. Next: Java instance - the thread priority settingsĭeadlock is a situation: a plurality of threads are blocked, one or all of them are waiting for a resource to be released. Important Points : If threads are waiting for each other to finish, then the condition is known as Deadlock.
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