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Double-checked locking

Reports double-checked locking.

Double-checked locking tries to initialize a field on demand and in a thread-safe manner, while avoiding the cost of synchronization. Unfortunately it is not thread-safe when used on a field that is not declared volatile. When using Java 1.4 or earlier, double-checked locking doesn't work even with a volatile field. Read the article linked above for a detailed explanation of the problem.

Example of incorrect double-checked locking:

class Foo { private Helper helper = null; public Helper getHelper() { if (helper == null) synchronized(this) { if (helper == null) helper = new Helper(); } return helper; } } // other functions and members... }

Inspection Details

Available in:

IntelliJ IDEA 2023.3, Qodana for JVM 2023.3


Java, 233.SNAPSHOT

Last modified: 13 July 2023