src/hotspot/share/runtime/objectMonitor.hpp

rev 56044 : imported patch 8230184.patch
rev 56046 : v2.00 -> v2.05 (CR5/v2.05/8-for-jdk13) patches combined into one; merge with 8229212.patch; merge with jdk-14+11; merge with 8230184.patch.
rev 56048 : Add OM_CACHE_LINE_SIZE so that ObjectMonitor cache line sizes can be experimented with independently of DEFAULT_CACHE_LINE_SIZE; for SPARC and X64 configs that use 128 for DEFAULT_CACHE_LINE_SIZE, we are experimenting with 64; move _previous_owner_tid and _allocation_state fields to share the cache line with ObjectMonitor::_header; put ObjectMonitor::_ref_count on its own cache line after _owner; add 'int* count_p' parameter to deflate_monitor_list() and deflate_monitor_list_using_JT() and push counter updates down to where the ObjectMonitors are actually removed from the in-use lists; monitors_iterate() async deflation check should use negative ref_count; add 'JavaThread* target' param to deflate_per_thread_idle_monitors_using_JT() add deflate_common_idle_monitors_using_JT() to make it clear which JavaThread* is the target of the work and which is the calling JavaThread* (self); g_free_list, g_om_in_use_list and g_om_in_use_count are now static to synchronizer.cpp (reduce scope); add more diagnostic info to some assert()'s; minor code cleanups and code motion; save_om_ptr() should detect a race with a deflating thread that is bailing out and cause a retry when the ref_count field is not positive; merge with jdk-14+11; add special GC support for TestHumongousClassLoader.java; merge with 8230184.patch.
rev 56049 : Merge the remainder of the lock-free monitor list changes from v2.06 with v2.06a and v2.06b after running the changes through the edit scripts; merge pieces from dcubed.monitor_deflate_conc.v2.06d in dcubed.monitor_deflate_conc.v2.06[ac]; merge pieces from dcubed.monitor_deflate_conc.v2.06e into dcubed.monitor_deflate_conc.v2.06c; merge with jdk-14+11; test work around for test/jdk/tools/jlink/multireleasejar/JLinkMultiReleaseJarTest.java should not been needed anymore.

@@ -157,23 +157,17 @@
     Free = 0,  // Free must be 0 for monitor to be free after memset(..,0,..).
     New,
     Old
   } AllocationState;
   AllocationState _allocation_state;
- public:
-  ObjectMonitor* _next_om;          // Next ObjectMonitor* linkage
- private:
   // Separate _header and _owner on different cache lines since both can
   // have busy multi-threaded access. _header, _object and _allocation_state
   // are set at initial inflation. _object and _allocation_state don't
   // change until deflation so _object and _allocation_state are good
-  // choices to share the cache line with _header. _next_om shares _header's
-  // cache line for pre-monitor list historical reasons. _next_om only
-  // changes if the next ObjectMonitor is deflated.
+  // choices to share the cache line with _header.
   DEFINE_PAD_MINUS_SIZE(0, OM_CACHE_LINE_SIZE, sizeof(volatile markWord) +
-                        sizeof(void* volatile) + sizeof(AllocationState) +
-                        sizeof(ObjectMonitor*));
+                        sizeof(void* volatile) + sizeof(AllocationState));
   // Used by async deflation as a marker in the _owner field:
   #define DEFLATER_MARKER reinterpret_cast<void*>(-1)
  protected:                         // protected for JvmtiRawMonitor
   void* volatile _owner;            // pointer to owning thread OR BasicLock
  private:

@@ -184,10 +178,16 @@
   // cache line with _owner.
   DEFINE_PAD_MINUS_SIZE(1, OM_CACHE_LINE_SIZE, sizeof(void* volatile) +
                         sizeof(volatile jlong));
   volatile jint _ref_count;         // ref count for ObjectMonitor* and used by the async deflation
                                     // protocol. See ObjectSynchronizer::deflate_monitor_using_JT().
+ private:
+  // Separate _ref_count and _next_om on different cache lines since
+  // both can have busy multi-threaded access.
+  DEFINE_PAD_MINUS_SIZE(2, OM_CACHE_LINE_SIZE, sizeof(volatile jint));
+ public:                            // for static synchronizer.cpp access:
+  ObjectMonitor* volatile _next_om;  // Next ObjectMonitor* linkage
  protected:                         // protected for JvmtiRawMonitor
   volatile intptr_t _recursions;    // recursion count, 0 for first entry
   ObjectWaiter* volatile _EntryList;  // Threads blocked on entry or reentry.
                                       // The list is actually composed of WaitNodes,
                                       // acting as proxies for Threads.

@@ -208,10 +208,11 @@
   volatile jint  _waiters;          // number of waiting threads
  private:
   volatile int _WaitSetLock;        // protects Wait Queue - simple spinlock
 
  public:
+  volatile int visit_marker;
   static void Initialize();
 
   // Only perform a PerfData operation if the PerfData object has been
   // allocated and if the PerfDataManager has not freed the PerfData
   // objects which can happen at normal VM shutdown.