Subtle concurrency errors in multithreaded libraries that arise because of incorrect or inadequate synchronization are often difficult to pinpoint precisely using only static techniques. On the other hand, the effectiveness of dynamic race detectors is critically dependent on multithreaded test suites whose execution can be used to identify and trigger races. Usually, such multithreaded tests need to invoke a specific combination of methods with objects involved in the invocations being shared appropriately to expose a race. Without a priori knowledge of the race, construction of such tests can be challenging.

We present NARADA a lightweight and scalable tool for synthesizing precisely these kinds of tests. Given a multithreaded library and a sequential test suite, NARAD performs a fully automated analysis that examines sequential execution traces, and produces as its output a concurrent client program that drives shared objects via library method calls to states conducive for triggering a race. Experimental results on a variety of well-tested Java libraries yield 101 synthesized multithreaded tests in less than four minutes. Analyzing the execution of these tests using an off-the-shelf race detector reveals 187 harmful races, including several previously unreported ones.


  • Download three tools (omen+, narada and intruder) as VM image here

  • Download the VM image here

  • Download the tar ball here

Using Narada

VM Image : If you have downloaded the VM image follow the link here for usage instructions.

TAR Ball : If you have downloaded the tar ball follow the link here for usage instructions.

Relevant Paper

  • Synthesizing Racy Tests pdf


Malavika Samak

Murali Krishna Ramanathan

Suresh Jagannathan

Tool Promotion Video