From 368945608cd50d561d6b73ddf147fef5f281a714 Mon Sep 17 00:00:00 2001
From: stefank <unknown>
Date: Mon, 27 May 2013 12:58:42 +0200
Subject: [PATCH] 8015422: Large performance hit when the StringTable is walked
 twice in Parallel Scavenge Summary: Combine the calls to StringTable::unlink
 and StringTable::oops_do in Parallel Scavenge. Reviewed-by: pliden, coleenp

---
 src/share/vm/classfile/symbolTable.cpp                    | 5 ++++-
 src/share/vm/classfile/symbolTable.hpp                    | 5 ++++-
 .../vm/gc_implementation/parallelScavenge/psScavenge.cpp  | 8 +++-----
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/share/vm/classfile/symbolTable.cpp b/src/share/vm/classfile/symbolTable.cpp
index f4590c62f..c78ea2d35 100644
--- a/src/share/vm/classfile/symbolTable.cpp
+++ b/src/share/vm/classfile/symbolTable.cpp
@@ -737,7 +737,7 @@ oop StringTable::intern(const char* utf8_string, TRAPS) {
   return result;
 }
 
-void StringTable::unlink(BoolObjectClosure* is_alive) {
+void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
   // Readers of the table are unlocked, so we should only be removing
   // entries at a safepoint.
   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
@@ -748,6 +748,9 @@ void StringTable::unlink(BoolObjectClosure* is_alive) {
       assert(!entry->is_shared(), "CDS not used for the StringTable");
 
       if (is_alive->do_object_b(entry->literal())) {
+        if (f != NULL) {
+          f->do_oop((oop*)entry->literal_addr());
+        }
         p = entry->next_addr();
       } else {
         *p = entry->next();
diff --git a/src/share/vm/classfile/symbolTable.hpp b/src/share/vm/classfile/symbolTable.hpp
index a2896382f..4701e74b5 100644
--- a/src/share/vm/classfile/symbolTable.hpp
+++ b/src/share/vm/classfile/symbolTable.hpp
@@ -272,7 +272,10 @@ public:
 
   // GC support
   //   Delete pointers to otherwise-unreachable objects.
-  static void unlink(BoolObjectClosure* cl);
+  static void unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f);
+  static void unlink(BoolObjectClosure* cl) {
+    unlink_or_oops_do(cl, NULL);
+  }
 
   // Invoke "f->do_oop" on the locations of all oops in the table.
   static void oops_do(OopClosure* f);
diff --git a/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp b/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp
index 72d2df4b9..f209a802b 100644
--- a/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp
+++ b/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp
@@ -450,11 +450,9 @@ bool PSScavenge::invoke_no_policy() {
       reference_processor()->enqueue_discovered_references(NULL);
     }
 
-      // Unlink any dead interned Strings
-      StringTable::unlink(&_is_alive_closure);
-      // Process the remaining live ones
-      PSScavengeRootsClosure root_closure(promotion_manager);
-      StringTable::oops_do(&root_closure);
+    // Unlink any dead interned Strings and process the remaining live ones.
+    PSScavengeRootsClosure root_closure(promotion_manager);
+    StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
 
     // Finally, flush the promotion_manager's labs, and deallocate its stacks.
     PSPromotionManager::post_scavenge();
-- 
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