Compile-The-World (CTW) is a useful tool to verify JIT compilers in HotSpot. User can specify a jar file or a java module, the driver of ctw compiles them all.

When we develop a new feature of a JIT compiler, we would like to track the quality of the feature, or the percentage of methods we can compile or optimize. We expect to have 'keep-going' mode like 'make -k'. Even though it encounters a critical error, the driver can skip it and proceed.

This isn't trivial in the current single process model. Some compiler errors cause segment fault and abort the JVM process. If we don't want to change the error handling of CompilerThread, We need to change driver. We only commit pass/fail state of a compilation task and restart the JVM when an error is fatal.