src/hotspot/share/jfr/leakprofiler/leakProfiler.cpp

*** 32,19 ***
  #include "memory/iterator.hpp"
  #include "runtime/javaThread.inline.hpp"
  #include "runtime/vmThread.hpp"
  
  bool LeakProfiler::is_supported() {
!   if (UseShenandoahGC || UseZGC) {
!     // Leak Profiler uses mark words in the ways that might interfere
!     // with concurrent GC uses of them. This affects Shenandoah.
!     //
!     // Generational ZGC only does weak reference processing in the old generation.
!     // All objects that would usually die, because we are sampling stuff
!     // that immediately becomes garbage, will be artificially kept alive
!     // until an old-generation collection. This incurs a significant
!     // performance hit by causing allocation stalls.
      return false;
    }
    return true;
  }
  
--- 32,21 ---
  #include "memory/iterator.hpp"
  #include "runtime/javaThread.inline.hpp"
  #include "runtime/vmThread.hpp"
  
  bool LeakProfiler::is_supported() {
!   if (UseCompactObjectHeaders || UseShenandoahGC || UseZGC) {
!     // 1. With a 32-bit mark word in Lilliput2, we don't have enough unused
!     //    bits to store edge index information in the mark word
!     // 2. Even without compressed object headers, with Shenandoah, we don't
!     //    have enough free bits in the mark word because of needing that
!     //    space for forwarding pointers in the evacuation & update refs phase.
!     // 3. Generational ZGC only does weak reference processing in the old generation.
!     //    All objects that would usually die, because we are sampling stuff
!     //    that immediately becomes garbage, will be artificially kept alive
+     //    until an old-generation collection. This incurs a significant
+     //    performance hit by causing allocation stalls.
      return false;
    }
    return true;
  }