src/hotspot/share/gc/z/zNMethodTable.cpp

rev 53842 : 8219462: ZGC: Use wait/notify in ZNMethodTable

@@ -38,11 +38,10 @@
 #include "logging/log.hpp"
 #include "memory/allocation.inline.hpp"
 #include "memory/resourceArea.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/orderAccess.hpp"
-#include "runtime/os.hpp"
 #include "utilities/debug.hpp"
 
 class ZNMethodDataImmediateOops {
 private:
   const size_t _nimmediate_oops;

@@ -438,28 +437,28 @@
 
   // Disarm nmethod entry barrier
   disarm_nmethod(nm);
 }
 
-void ZNMethodTable::sweeper_wait_for_iteration() {
-  // The sweeper must wait for any ongoing iteration to complete
-  // before it can unregister an nmethod.
-  if (!Thread::current()->is_Code_cache_sweeper_thread()) {
-    return;
-  }
+void ZNMethodTable::wait_until_iteration_done() {
+  assert(CodeCache_lock->owned_by_self(), "Lock must be held");
 
   while (_iter_table != NULL) {
-    MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
-    os::naked_short_sleep(1);
+    CodeCache_lock->wait(Monitor::_no_safepoint_check_flag);
   }
 }
 
 void ZNMethodTable::unregister_nmethod(nmethod* nm) {
   assert(CodeCache_lock->owned_by_self(), "Lock must be held");
-  ResourceMark rm;
 
-  sweeper_wait_for_iteration();
+  if (Thread::current()->is_Code_cache_sweeper_thread()) {
+    // The sweeper must wait for any ongoing iteration to complete
+    // before it can unregister an nmethod.
+    ZNMethodTable::wait_until_iteration_done();
+  }
+
+  ResourceMark rm;
 
   log_unregister(nm);
 
   // Remove entry
   unregister_entry(_table, _size, nm);

@@ -492,18 +491,22 @@
   // Finish iteration
   if (_iter_table != _table) {
     delete [] _iter_table;
   }
   _iter_table = NULL;
+
   assert(_claimed >= _iter_table_size, "Failed to claim all table entries");
 
   // Process deferred deletes
   ZArrayIterator<void*> iter(&_iter_deferred_deletes);
   for (void* data; iter.next(&data);) {
     FREE_C_HEAP_ARRAY(uint8_t, data);
   }
   _iter_deferred_deletes.clear();
+
+  // Notify iteration done
+  CodeCache_lock->notify_all();
 }
 
 void ZNMethodTable::entry_oops_do(ZNMethodTableEntry entry, OopClosure* cl) {
   nmethod* const nm = entry.method();