Thread-local storage (TLS) in multithreading

Each thread has its own instance of a map that stores thread-local variables.

This map holds the associations between the thread-local variables and their corresponding values, ensuring that the variables are unique to the thread and are not shared across other threads.

This allows threads to maintain isolated states, preventing race conditions and ensuring data consistency within each thread.

public static ThreadLocal<Student> studentThreadLocal = new ThreadLocal<Student>();

studentThreadLocal has the global scope, but the value inside the studentThreadLocal has the scope only for the duration of a thread

//Sets the current thread's value
studentThreadLocal.set(new Student("Harry Potter"));

//gets the current thread's value'
studentThreadLocal.get();

Inheritable ThreadLocal

InheritableThreadLocal is a subclass of ThreadLocal. It allows child threads to inherit the values of the parent thread.

• By Default child thread values are identical to Parent Thread.

When a child thread gets created the the local values of parent get copied over to the child in 2 ways

• Default copy is shallow copy (pointer to the original is saved with the child)
  • If the child thread sets a new value, parent thread will see the updated value

// InheritableThreadLocal variable
private static final InheritableThreadLocal<String> threadLocalValue = new InheritableThreadLocal<>();