AFAICT tracing back through the intermediate builds this is due to something in build 262 including

2020-02-05 17:33
erikj: 023df1 - OpenJDK
8238225 Issues reported after replacing symlink at Contents/MacOS/libjli.dylib with binary
2020-02-05 16:40
dcubed: b35341 - OpenJDK
8235795 replace monitor list mux{Acquire,Release}(&gListLock) with spin locks
2020-02-05 16:39
dcubed: 00470b - OpenJDK
8236035 refactor ObjectMonitor::set_owner() and _owner field setting
2020-02-05 16:38
dcubed: 175867 - OpenJDK
8235931 add OM_CACHE_LINE_SIZE and use smaller size on SPARCv9 and X64
Build

This is seen on Linux and Windows in our OCI perf machines.