Avoid verifying heap while sweeper is running.

runtime/vm/pages.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/pages.h"
 
 #include "platform/assert.h"
 #include "vm/compiler_stats.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
@@ skipping 638 matching lines @@
   NoHandleScope no_handles(isolate);
 
   if (FLAG_print_free_list_before_gc) {
     OS::Print("Data Freelist (before GC):\n");
     freelist_[HeapPage::kData].Print();
     OS::Print("Executable Freelist (before GC):\n");
     freelist_[HeapPage::kExecutable].Print();
   }
 
   if (FLAG_verify_before_gc) {
-    OS::PrintErr("Verifying before MarkSweep...");
+    OS::PrintErr("Verifying before marking...");
     heap_->Verify();
     OS::PrintErr(" done.\n");
   }
 
   const int64_t start = OS::GetCurrentTimeMicros();
 
   // Make code pages writable.
   WriteProtectCode(false);
 
   // Save old value before GCMarker visits the weak persistent handles.
@@ skipping 12 matching lines @@
   bump_top_ = 0;
   bump_end_ = 0;
   // Reset the freelists and setup sweeping.
   freelist_[HeapPage::kData].Reset();
   freelist_[HeapPage::kExecutable].Reset();
 
   int64_t mid2 = OS::GetCurrentTimeMicros();
   int64_t mid3 = 0;
 
   {
+    if (FLAG_verify_before_gc) {
+      OS::PrintErr("Verifying before sweeping...");
+      heap_->Verify(kAllowMarked);
+      OS::PrintErr(" done.\n");
+    }
     GCSweeper sweeper;
 
     // During stop-the-world phases we should use bulk lock when adding elements
     // to the free list.
     MutexLocker mld(freelist_[HeapPage::kData].mutex());
     MutexLocker mle(freelist_[HeapPage::kExecutable].mutex());
 
     // Large and executable pages are always swept immediately.
     HeapPage* prev_page = NULL;
     HeapPage* page = large_pages_;
@@ skipping 35 matching lines @@
         HeapPage* next_page = page->next();
         bool page_in_use = sweeper.SweepPage(page, &freelist_[page->type()]);
         if (page_in_use) {
           prev_page = page;
         } else {
           FreePage(page, prev_page);
         }
         // Advance to the next page.
         page = next_page;
       }
+      if (FLAG_verify_after_gc) {
+        OS::PrintErr("Verifying after sweeping...");
+        heap_->Verify(kForbidMarked);
+        OS::PrintErr(" done.\n");
+      }
     } else {
       // Start the concurrent sweeper task now.
       GCSweeper::SweepConcurrent(
           isolate, pages_, pages_tail_, &freelist_[HeapPage::kData]);
     }
   }
 
   // Make code pages read-only.
   WriteProtectCode(true);
 
   int64_t end = OS::GetCurrentTimeMicros();
 
   // Record signals for growth control. Include size of external allocations.
   page_space_controller_.EvaluateGarbageCollection(usage_before, usage_,
                                                    start, end);
 
   heap_->RecordTime(kMarkObjects, mid1 - start);
   heap_->RecordTime(kResetFreeLists, mid2 - mid1);
   heap_->RecordTime(kSweepPages, mid3 - mid2);
   heap_->RecordTime(kSweepLargePages, end - mid3);
 
   if (FLAG_print_free_list_after_gc) {
     OS::Print("Data Freelist (after GC):\n");
     freelist_[HeapPage::kData].Print();
     OS::Print("Executable Freelist (after GC):\n");
     freelist_[HeapPage::kExecutable].Print();
   }
 
-  if (FLAG_verify_after_gc) {
-    OS::PrintErr("Verifying after MarkSweep...");
-    heap_->Verify(FLAG_concurrent_sweep ? kAllowMarked : kForbidMarked);
-    OS::PrintErr(" done.\n");
-  }
-
   // Done, reset the task count.
   {
     MonitorLocker ml(tasks_lock());
     set_tasks(tasks() - 1);
     ml.Notify();
   }
 }
 
 
 uword PageSpace::TryAllocateDataBumpInternal(intptr_t size,
@@ skipping 201 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result= static_cast<int>((static_cast<double>(gc_time) /
                              static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart