8224119: Safepoint cleanup logging logs times for things it doesn't do

Test condition before reporting times for cleanup actions.

Reviewed-by: rehn, hseigel

src/hotspot/share/classfile/classLoaderDataGraph.cpp

@@ -596,16 +596,15 @@ void ClassLoaderDataGraph::purge() {
   DependencyContext::purge_dependency_contexts();
 }
 
-int ClassLoaderDataGraph::resize_if_needed() {
+int ClassLoaderDataGraph::resize_dictionaries() {
   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
   int resized = 0;
-  if (Dictionary::does_any_dictionary_needs_resizing()) {
+  assert (Dictionary::does_any_dictionary_needs_resizing(), "some dictionary should need resizing");
   FOR_ALL_DICTIONARY(cld) {
     if (cld->dictionary()->resize_if_needed()) {
       resized++;
     }
   }
-  }
   return resized;
 }
 

src/hotspot/share/classfile/classLoaderDataGraph.hpp

@@ -119,16 +119,14 @@ class ClassLoaderDataGraph : public AllStatic {
   static GrowableArray<ClassLoaderData*>* new_clds();
 
   static void set_should_purge(bool b) { _should_purge = b; }
-  static void purge_if_needed() {
-    // Only purge the CLDG for CMS if concurrent sweep is complete.
-    if (_should_purge) {
-      purge();
+  static bool should_purge_and_reset() {
+    bool res = _should_purge;
     // reset for next time.
     set_should_purge(false);
-    }
+    return res;
   }
 
-  static int resize_if_needed();
+  static int resize_dictionaries();
 
   static bool has_metaspace_oom()           { return _metaspace_oom; }
   static void set_metaspace_oom(bool value) { _metaspace_oom = value; }

src/hotspot/share/runtime/safepoint.cpp

@@ -24,6 +24,7 @@
 
 #include "precompiled.hpp"
 #include "classfile/classLoaderDataGraph.inline.hpp"
+#include "classfile/dictionary.hpp"
 #include "classfile/stringTable.hpp"
 #include "classfile/symbolTable.hpp"
 #include "classfile/systemDictionary.hpp"
@@ -610,24 +611,28 @@ public:
     }
 
     if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_CLD_PURGE)) {
+      if (ClassLoaderDataGraph::should_purge_and_reset()) {
         // CMS delays purging the CLDG until the beginning of the next safepoint and to
         // make sure concurrent sweep is done
         const char* name = "purging class loader data graph";
         EventSafepointCleanupTask event;
         TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
-      ClassLoaderDataGraph::purge_if_needed();
+        ClassLoaderDataGraph::purge();
 
         post_safepoint_cleanup_task_event(event, safepoint_id, name);
       }
+    }
 
     if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) {
+      if (Dictionary::does_any_dictionary_needs_resizing()) {
         const char* name = "resizing system dictionaries";
         EventSafepointCleanupTask event;
         TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
-      ClassLoaderDataGraph::resize_if_needed();
+        ClassLoaderDataGraph::resize_dictionaries();
 
         post_safepoint_cleanup_task_event(event, safepoint_id, name);
       }
+    }
 
     _subtasks.all_tasks_completed(_num_workers);
   }

test/hotspot/jtreg/runtime/logging/SafepointCleanupTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2019, 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
@@ -43,7 +43,6 @@ public class SafepointCleanupTest {
         output.shouldContain("deflating per-thread idle monitors");
         output.shouldContain("updating inline caches");
         output.shouldContain("compilation policy safepoint handler");
-        output.shouldContain("purging class loader data graph");
         output.shouldHaveExitValue(0);
     }