The Java Concurrency Stress Test (jcstress) is a set of tests for testing the correctness of the Java concurrency support. This is a new tool that is mostly targeted to Java 8, which means that not all the tests will run on previous versions of Java. As a new tool, jcstress is in its alpha phase and changes for fixes and improvements are common, which means that whoever is working with it is expected to update the source code and rebuild the tool relatively often.

Testing concurrency is not an easy task and it may or may not be easy to make such tests fail even with incorrect code. This happens due to the nature of concurrent code, which might work differently on different hardware configurations. Such variations arise from the number of CPUs or the CPU architecture. Overall, this means that many tests in jcstress are uncertain and they might require a long time before exposing potential problems.