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rev 6670 : 8048085: Aborting marking just before remark results in useless additional clearing of the next mark bitmap
Summary: After concurrent mark abort due to Full GC G1 unnecessarily clears the next mark bitmap a second time concurrently. The Full GC mark abort procedure already did that. Before clearing the next mark bitmap, check whether mark abort occurred to avoid this work.
Reviewed-by: tbd
rev 6671 : imported patch bengt-fixes
rev 6672 : imported patch bengt-fixes2

@@ -275,13 +275,17 @@
       // We now want to allow clearing of the marking bitmap to be
       // suspended by a collection pause.
-      {
+      // We may have aborted just before the remark. Do not bother clearing the
+      // bitmap then, as it has been done during mark abort.
+      if (!cm()->has_aborted()) {
         SuspendibleThreadSetJoiner sts;
+      } else {
+        assert(!G1VerifyBitmaps || _cm->nextMarkBitmapIsClear(), "Next mark bitmap must be clear");
     // Update the number of full collections that have been
     // completed. This will also notify the FullGCCount_lock in case a