With the last 2 releases (so starting in 0.5.8) we've been hitting a crashing bug in which garbage collection operations seem to cause a crash of the JVM. This only seems to occur with coverage enabled (so not when running under the debugger or normally). This also does not reproduce with versions of JaCoCo prior to the last 2. Sorry I don't have more information - I'm trying to narrow down some repro steps but this bug only reproduces for one of our larger tests suites so that would be a lot of code to get running. I've tried playing around with the memory settings and even with a lot of perm-gen and heap memory the issue still reproduces. I've also tried Java 6 and 7 and both reproduce the issue as well.