Yes, they do. Many people don't get the point across that Java is like C and C++, there are plenty of implementations.
Regarding OpenJDK, here are some examples,
Amazon has Lambda SnapStart into their implementation, Azul uses a LLVM based JIT, their own pauseless GC and extensions for value types (ObjectLayout), Red-Hat ships Shenodah.
Regarding OpenJDK, here are some examples,
Amazon has Lambda SnapStart into their implementation, Azul uses a LLVM based JIT, their own pauseless GC and extensions for value types (ObjectLayout), Red-Hat ships Shenodah.