src/share/vm/gc/shared/genCollectedHeap.cpp

rev 11983 : 8166276: Refactor gen_process_roots to allow simpler fix for 8165949
Reviewed-by:
Contributed-by: jesper.wilhelmsson@oracle.com
rev 11985 : 8165949: Serial and ConcMarkSweep do not unload strings when class unloading is disabled
Reviewed-by:
rev 11986 : imported patch 8165949-on-jesper-mik-rev
rev 11987 : [mq]: 8165949-on-jesper-stefank-rev

@@ -611,20 +611,10 @@
 
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
     SystemDictionary::roots_oops_do(strong_roots, weak_roots);
   }
 
-  // All threads execute the following. A specific chunk of buckets
-  // from the StringTable are the individual tasks.
-  if (weak_roots != NULL) {
-    if (is_par) {
-      StringTable::possibly_parallel_oops_do(weak_roots);
-    } else {
-      StringTable::oops_do(weak_roots);
-    }
-  }
-
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
     if (so & SO_ScavengeCodeCache) {
       assert(code_roots != NULL, "must supply closure for code cache");
 
       // We only visit parts of the CodeCache when scavenging.

@@ -642,18 +632,31 @@
     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
   }
 }
 
+void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
+                                                  OopClosure* root_closure) {
+  assert(root_closure != NULL, "Must be set");
+  // All threads execute the following. A specific chunk of buckets
+  // from the StringTable are the individual tasks.
+  if (scope->n_threads() > 1) {
+    StringTable::possibly_parallel_oops_do(root_closure);
+  } else {
+    StringTable::oops_do(root_closure);
+  }
+}
+
 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
                                            OopsInGenClosure* root_closure,
                                            OopsInGenClosure* old_gen_closure,
                                            CLDClosure* cld_closure) {
   MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
 
   process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
                 cld_closure, cld_closure, &mark_code_closure);
+  process_string_table_roots(scope, root_closure);
 
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
     root_closure->reset_generation();
   }
 

@@ -675,10 +678,13 @@
   MarkingCodeBlobClosure mark_code_closure(root_closure, !CodeBlobToOopClosure::FixRelocations);
   OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
 
   process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
+  if (!only_strong_roots) {
+    process_string_table_roots(scope, root_closure);
+  }
 
   if (young_gen_as_roots &&
       !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
     root_closure->set_generation(_young_gen);
     _young_gen->oop_iterate(root_closure);

@@ -687,20 +693,26 @@
 
   _process_strong_tasks->all_tasks_completed(scope->n_threads());
 }
 
 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
-                                          bool only_strong_roots,
-                                          ScanningOption so,
                                           bool is_adjust_phase,
+                                          ScanningOption so,
+                                          bool only_strong_roots,
                                           OopsInGenClosure* root_closure,
                                           CLDClosure* cld_closure) {
   MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
-  OopsInGenClosure* weak_roots = is_adjust_phase ? root_closure : NULL;
+  OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
 
   process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
+  if (is_adjust_phase) {
+    // We never treat the string table as roots during marking
+    // for the full gc, so we only need to process it during
+    // the adjust phase.
+    process_string_table_roots(scope, root_closure);
+  }
 
   _process_strong_tasks->all_tasks_completed(scope->n_threads());
 }
 
 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {