src/share/vm/memory/referenceProcessor.cpp

rev 2869 : 7117303: VM uses non-monotonic time source and complains that it is non-monotonic
Summary: Replaces calls to os::javaTimeMillis(), which does not guarantee montonicity, in GC code to os::javaTimeNanos() with a suitable conversion factor. os::javaTimeNanos() mostly guarantees montonicity depending on the underlying OS implementation and, as a result, a better alternative. Changes in OS files are to make use of the newly defined constants in globalDefinitions.hpp.
Reviewed-by:

@@ -41,11 +41,12 @@
 void referenceProcessor_init() {
   ReferenceProcessor::init_statics();
 }
 
 void ReferenceProcessor::init_statics() {
-  jlong now = os::javaTimeMillis();
+  // os::javaTimeMillis() does not guarantee monotonicity.
+  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
 
   // Initialize the soft ref timestamp clock.
   _soft_ref_timestamp_clock = now;
   // Also update the soft ref clock in j.l.r.SoftReference
   java_lang_ref_SoftReference::set_clock(_soft_ref_timestamp_clock);

@@ -149,11 +150,13 @@
 }
 
 void ReferenceProcessor::update_soft_ref_master_clock() {
   // Update (advance) the soft ref master clock field. This must be done
   // after processing the soft ref list.
-  jlong now = os::javaTimeMillis();
+
+  // os::javaTimeMillis() does not guarantee monotonicity.
+  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
   jlong soft_ref_clock = java_lang_ref_SoftReference::clock();
   assert(soft_ref_clock == _soft_ref_timestamp_clock, "soft ref clocks out of sync");
 
   NOT_PRODUCT(
   if (now < _soft_ref_timestamp_clock) {