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diff src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp @ 2152:0fa27f37d4d4

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6977804: G1: remove the zero-filling thread Summary: This changeset removes the zero-filling thread from G1 and collapses the two free region lists we had before (the "free" and "unclean" lists) into one. The new free list uses the new heap region sets / lists abstractions that we'll ultimately use it to keep track of all regions in the heap. A heap region set was also introduced for the humongous regions. Finally, this change increases the concurrency between the thread that completes freeing regions (after a cleanup pause) and the rest of the system (before we'd have to wait for said thread to complete before allocating a new region). The changest also includes a lot of refactoring and code simplification. Reviewed-by: jcoomes, johnc
author tonyp
date Wed, 19 Jan 2011 19:30:42 -0500
parents fb712ff22571
children a672e43650cc
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp	Wed Jan 19 13:04:37 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp	Wed Jan 19 19:30:42 2011 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, 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
@@ -95,8 +95,8 @@
   _vtime_start = os::elapsedVTime();
   wait_for_universe_init();
 
-  G1CollectedHeap* g1 = G1CollectedHeap::heap();
-  G1CollectorPolicy* g1_policy = g1->g1_policy();
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  G1CollectorPolicy* g1_policy = g1h->g1_policy();
   G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
   Thread *current_thread = Thread::current();
 
@@ -119,7 +119,7 @@
       if (!g1_policy->in_young_gc_mode()) {
         // this ensures the flag is not set if we bail out of the marking
         // cycle; normally the flag is cleared immediately after cleanup
-        g1->set_marking_complete();
+        g1h->set_marking_complete();
 
         if (g1_policy->adaptive_young_list_length()) {
           double now = os::elapsedTime();
@@ -228,10 +228,20 @@
         VM_CGC_Operation op(&cl_cl, verbose_str);
         VMThread::execute(&op);
       } else {
-        G1CollectedHeap::heap()->set_marking_complete();
+        g1h->set_marking_complete();
       }
 
-      if (!cm()->has_aborted()) {
+      // Check if cleanup set the free_regions_coming flag. If it
+      // hasn't, we can just skip the next step.
+      if (g1h->free_regions_coming()) {
+        // The following will finish freeing up any regions that we
+        // found to be empty during cleanup. We'll do this part
+        // without joining the suspendible set. If an evacuation pause
+        // takes places, then we would carry on freeing regions in
+        // case they are needed by the pause. If a Full GC takes
+        // places, it would wait for us to process the regions
+        // reclaimed by cleanup.
+
         double cleanup_start_sec = os::elapsedTime();
         if (PrintGC) {
           gclog_or_tty->date_stamp(PrintGCDateStamps);
@@ -240,23 +250,22 @@
         }
 
         // Now do the remainder of the cleanup operation.
-        _sts.join();
         _cm->completeCleanup();
-        if (!cm()->has_aborted()) {
-          g1_policy->record_concurrent_mark_cleanup_completed();
+        g1_policy->record_concurrent_mark_cleanup_completed();
 
-          double cleanup_end_sec = os::elapsedTime();
-          if (PrintGC) {
-            gclog_or_tty->date_stamp(PrintGCDateStamps);
-            gclog_or_tty->stamp(PrintGCTimeStamps);
-            gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]",
-                                   cleanup_end_sec - cleanup_start_sec);
-          }
+        double cleanup_end_sec = os::elapsedTime();
+        if (PrintGC) {
+          gclog_or_tty->date_stamp(PrintGCDateStamps);
+          gclog_or_tty->stamp(PrintGCTimeStamps);
+          gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]",
+                                 cleanup_end_sec - cleanup_start_sec);
         }
-        _sts.leave();
+
+        // We're done: no more free regions coming.
+        g1h->reset_free_regions_coming();
       }
-      // We're done: no more unclean regions coming.
-      G1CollectedHeap::heap()->set_unclean_regions_coming(false);
+      guarantee(cm()->cleanup_list_is_empty(),
+                "at this point there should be no regions on the cleanup list");
 
       if (cm()->has_aborted()) {
         if (PrintGC) {
@@ -278,7 +287,7 @@
     // Java thread is waiting for a full GC to happen (e.g., it
     // called System.gc() with +ExplicitGCInvokesConcurrent).
     _sts.join();
-    g1->increment_full_collections_completed(true /* concurrent */);
+    g1h->increment_full_collections_completed(true /* concurrent */);
     _sts.leave();
   }
   assert(_should_terminate, "just checking");