Lock contention is the situation when one thread is waiting for a

lock/object that being held by another thread. The waiting thread

cannot use this object until the other thread releases the lock on that

object.

It is also known as Thread contention.

Ideally locks reduce the thread contention. Without locks, multiple

threads can operate on same object and cause undesirable behavior.

If locking is implemented correctly it reduces the occurrence of

contention between multiple threads.

https://www.ibm.com/docs/en/mon-diag-tools?topic=perspective-resolving-lock-contention