Java G1 fix would speed JIT compilation
A change to Java’s G1 garbage collector would lower the memory and processing overhead and speed the execution of Java’s C2 optimizing JIT (just-in-time) compiler, benefiting cloud deployments, under a proposal in the Java community.
The OpenJDK proposal would simplify the implementation of G1’s barriers, which record information about application memory accesses, by shifting their expansion from early in the C2 JIT's compilation pipeline to later, the proposal states.
Underlying this proposal is the increasing popularity of cloud-based Java deployments, which has led to a stronger focus on reducing overall JVM overhead. Goals of the plan include reducing the execution of time of C2 when using the G1 collector, making G1 barriers comprehensible to HotSpot developers who lack a deep understanding of C2, and guaranteeing that C2 preserves invariants about the relative ordering of memory accesses, safepoints, and barriers. Another goal is preserving the quality of C2-generated code in terms of speed and size.