What is synchronize block?
A synchronized block in Java is synchronized on some object. All synchronized blocks synchronized on the same object can only have one thread executing inside them at the same time. All other threads attempting to enter the synchronized block are blocked until the thread inside the synchronized block exits the block.
Are intrinsic locks reentrant?
Intrinsic lock are reentrant. That means once a thread has acquired the lock on a method it doesn't need to acquired the lock on calling other method of the same object.
What is a reentrant lock?
A ReentrantLock is owned by the thread last successfully locking, but not yet unlocking it. A thread invoking lock will return, successfully acquiring the lock, when the lock is not owned by another thread. The method will return immediately if the current thread already owns the lock.
Is synchronized in Java reentrant?
Synchronized blocks in Java are reentrant. This means, that if a Java thread enters a synchronized block of code, and thereby take the lock on the monitor object the block is synchronized on, the thread can enter other Java code blocks synchronized on the same monitor object.
Is synchronized a lock?
Locks In Synchronized Methods When a thread invokes a synchronized method, it automatically acquires the intrinsic lock for that method's object and releases it when the method returns. The lock release occurs even if the return was caused by an uncaught exception.
What is the difference between a non reentrant lock and a reentrant lock?
If a lock is non re-entrant you could grab the lock, then block when you go to grab it again, effectively deadlocking your own process. Reentrancy in general is a property of code where it has no central mutable state that could be corrupted if the code was called while it is executing.