The role of volatile keyword in java

The role of the volatile keyword in Java is: Visibility: Ensure the visibility of variable modifications in a multi-threaded environment. Orderliness: Ensure that variable modifications are orderly to other threads. Usage scenarios: Mark shared variables to ensure visibility and orderliness and avoid lock overhead.

The role of volatile keyword in Java

The volatile keyword is used to declare a variable in Java. Variables guarantee visibility and ordering in a multi-threaded environment.

Visibility

• When one thread modifies a variable declared volatile, other threads can immediately see the modification.
• This is done to prevent threads from not seeing changes made by other threads due to cached copies of variables.

Orderliness

• The modification of volatile variables has orderliness to other threads, which means:

  • Other threads see modifications in the same order as they occurred.
  • Volatile variables are modified before ordinary variables are modified (following the happens-before principle).

Usage scenarios

volatile keyword is usually used in the following scenarios:

• Mark shared variables , to ensure visibility and orderliness in a multi-threaded environment.
• Used when synchronization is not required but visibility and ordering need to be ensured.
• Avoid the overhead of using locks because it is lightweight than synchronization.

Other Notes

• volatile variables do not provide atomicity. This means that multiple threads cannot modify volatile variables simultaneously.
• volatile variables are not guaranteed to be thread-safe. It only ensures visibility and orderliness.

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