src/hotspot/share/gc/shared/stringdedup/stringDedupTable.cpp

rev 57656 : 8236878: Use atomic instruction to update StringDedupTable's entries and entries_removed counters

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.

@@ -213,11 +213,11 @@
 const double             StringDedupTable::_max_cache_factor = 0.1; // Cache a maximum of 10% of the table size
 const uintx              StringDedupTable::_rehash_multiple = 60;   // Hash bucket has 60 times more collisions than expected
 const uintx              StringDedupTable::_rehash_threshold = (uintx)(_rehash_multiple * _grow_load_factor);
 
 uintx                    StringDedupTable::_entries_added = 0;
-uintx                    StringDedupTable::_entries_removed = 0;
+volatile uintx           StringDedupTable::_entries_removed = 0;
 uintx                    StringDedupTable::_resize_count = 0;
 uintx                    StringDedupTable::_rehash_count = 0;
 
 StringDedupTable*        StringDedupTable::_resized_table = NULL;
 StringDedupTable*        StringDedupTable::_rehashed_table = NULL;

@@ -477,13 +477,13 @@
     removed += unlink_or_oops_do(cl, table_half + partition_begin, table_half + partition_end, worker_id);
   }
 
   // Delayed update to avoid contention on the table lock
   if (removed > 0) {
-    MutexLocker ml(StringDedupTable_lock, Mutex::_no_safepoint_check_flag);
-    _table->_entries -= removed;
-    _entries_removed += removed;
+    assert_locked_or_safepoint_weak(StringDedupTable_lock);
+    Atomic::sub(&_table->_entries, removed);
+    Atomic::add(&_entries_removed, removed);
   }
 }
 
 uintx StringDedupTable::unlink_or_oops_do(StringDedupUnlinkOrOopsDoClosure* cl,
                                           size_t partition_begin,