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7117303: VM uses non-monotonic time source and complains that it is non-monotonic

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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
This commit is contained in:
John Cuthbertson 2011-12-19 10:02:05 -08:00
parent 2768349b41
commit 870bea622a
10 changed files with 57 additions and 57 deletions
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7
hotspot/src/share/vm/memory/generation.hpp
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@ -413,10 +413,13 @@ class Generation: public CHeapObj {
// 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;