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diff src/share/vm/memory/generation.hpp @ 4712:e7dead7e90af

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7117303: VM uses non-monotonic time source and complains that it is non-monotonic Summary: Replaces calls to os::javaTimeMillis(), which does not (and cannot) guarantee monotonicity, in GC code to an equivalent expression that uses os::javaTimeNanos(). os::javaTimeNanos is guaranteed monotonically non-decreasing if the underlying platform provides a monotonic time source. Changes in OS files are to make use of the newly defined constants in globalDefinitions.hpp. Reviewed-by: dholmes, ysr
author johnc
date Mon, 19 Dec 2011 10:02:05 -0800
parents 3c648b9ad052
children b632e80fc9dc
line wrap: on
line diff
--- a/src/share/vm/memory/generation.hpp	Fri Dec 16 11:40:00 2011 -0800
+++ b/src/share/vm/memory/generation.hpp	Mon Dec 19 10:02:05 2011 -0800
@@ -413,10 +413,13 @@
   // Time (in ms) when we were last collected or now if a collection is
   // in progress.
   virtual jlong time_of_last_gc(jlong now) {
-    // XXX See note in genCollectedHeap::millis_since_last_gc()
+    // Both _time_of_last_gc and now are set using a time source
+    // that guarantees monotonically non-decreasing values provided
+    // the underlying platform provides such a source. So we still
+    // have to guard against non-monotonicity.
     NOT_PRODUCT(
       if (now < _time_of_last_gc) {
-        warning("time warp: %d to %d", _time_of_last_gc, now);
+        warning("time warp: "INT64_FORMAT" to "INT64_FORMAT, _time_of_last_gc, now);
       }
     )
     return _time_of_last_gc;