The current CRaC implementation in HotSpot only supports checkpoint/restore engines implemented in form of executables. This was practical when using existing engines (e.g. CRIU) which are already implemented as executables. But this imposes restrictions on the form of interactions between JVM and the engine since it has to utilize inter-process communication. Engines developed with a CRaCed JVM as the main target can be implemented as dynamic libraries interaction with which is easier and more versatile.

This is a proposal to add the support of C/R engines in form of such libraries: the library will be loaded by the JVM and interactions with the engine will be implemented through the usual function calls.

Application-based engines can still be supported through a wrapper library.