Race condition in Java

A race condition is a design error in a multithreaded system or application in which this work directly depends on the order in which the threads are executed. A race condition occurs when the thread that should be executing at the beginning loses the race and another thread is executed first: the behavior of the code changes, resulting in non-deterministic errors.

Common solutions to solve the race condition problem

  • Using local copy - copying a shared variable to a thread local variable. This method works only when the variable is alone and copying is performed atomically (in one machine instruction), using volatile.
  • Synchronization - operations on a shared resource occur in a synchronized block (when using the synchronized keyword).
  • Combining methods - the above methods can be combined by copying "dangerous" variables in a synchronized block. On the one hand, this removes the restriction on atomicity, on the other hand, it allows you to get rid of too large synchronized blocks.

There is no obvious way to identify and correct race conditions. The best way to get rid of the races is to properly design your multitasking system.

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