Understanding Java.lang.Thread.State: WAITING

Understanding java.lang.Thread.State: WAITING (parking)

When a thread is in the Waiting state, it means that it is waiting for some external event to occur before it can continue to execute. This state is sometimes referred to as "parking" because the thread is waiting in a specific location, such as a park bench, while it waits for the external event to trigger it to continue. The most common causes of a thread entering the waiting state are when it is waiting to acquire a lock, waiting on a condition variable, or waiting for a signal from another thread.

When a thread is in the WAITING state, it is not actively doing any work and so it will not use up any CPU cycles. This state can be very beneficial in multi-threaded applications as it allows the thread to conserve system resources while it is idle. It is important to note, though, that this state can also lead to deadlocks if a thread is waiting for a resource that is already locked by another thread. Proper synchronization of shared resources is essential in order to avoid this situation.

It is also important to understand that if a thread remains in the WAITING state for too long, then it may indicate that there is a problem with the external event that it is waiting on. In these cases, it is important to investigate further to try and determine the root cause of the issue in order to prevent it from happening again in the future.