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How does immutability help?
Immutable objects are also useful because they are inherently thread-safe. Other benefits are that they are simpler to understand and reason about and offer higher security than mutable objects.
Does immutability guarantee thread safety?
Actually immutable objects are always thread-safe, but its references may not be. Going back to basic: Thread-safe simply means that two or more threads must work in coordination on the shared resource or object. They shouldn’t over-ride the changes done by any other thread.
How does a thread acquire a lock on an object?
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.
Is final variable thread-safe?
Final variables are immutable references, so a variable declared final is safe to access from multiple threads. You can only read the variable, not write it.
Can a thread can acquire more than one lock?
Reentrant means that locks are bound to the current thread. A thread can safely acquire the same lock multiple times without running into deadlocks (e.g. a synchronized method calls another synchronized method on the same object).
How does immutability minimize the need for locks?
Clearly Immutability minimizes the need for locks in multi-processor programming, but does it eliminate that need, or are there instances where immutability alone is not enough?
Is it a deal breaker to have an immutable object?
Having an immutable object with mutable members is usually a deal breaker). That’s it. It frees you from having to manage concurrency (via locks, snapshots, data partitioning or other mechanisms; the original question’s focus on locks is… Incorrect given the scope of the question).
What does it mean when an object is immutable?
Immutability gets you one thing: you can read the immutable object freely, without worrying about its state changing underneath you (assuming it is truly deeply immutable… Having an immutable object with mutable members is usually a deal breaker). That’s it.
How are locks used in the synchronization technique?
Locks are one synchronization technique. A lock is an abstraction that allows at most one thread to own it at a time. Holding a lock is how one thread tells other threads: “I’m changing this thing, don’t touch it right now.”. Locks have two operations: acquire allows a thread to take ownership of a lock.