Maxim Gekk created SPARK-26817:
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Summary: Use System.nanoTime to measure time intervals
Key: SPARK-26817
URL: https://issues.apache.org/jira/browse/SPARK-26817
Project: Spark
Issue Type: Improvement
Components: Spark Core
Affects Versions: 2.4.0
Reporter: Maxim Gekk
Replace System.currentTimeMillis() by System.nanoTime in time intervals
measurements. System.currentTimeMillis() returns current wallclock time and
will follow changes to the system clock. Thus, negative wallclock adjustments
can cause timeouts to "hang" for a long time (until wallclock time has caught
up to its previous value again). This can happen when ntpd does a "step" after
the network has been disconnected for some time. The most canonical example is
during system bootup when DHCP takes longer than usual. This can lead to
failures that are really hard to understand/reproduce. System.nanoTime() is
guaranteed to be monotonically increasing irrespective of wallclock changes.
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