JVM64bit running on Linux 64bit: when system time changes the JVM may hang (bug_id=6900441)
Andrew Haley
aph at redhat.com
Tue Sep 3 00:45:50 PDT 2013
On 09/02/2013 11:04 PM, David Holmes wrote:
> I strongly believe in two distinct notions of time: relative and
> absolute. Any API involving relative time should never be affected by
> changes to the absolute value of a clock; and anything involving
> absolute times obviously should.
I think that seems sensible. It may not be hard to come up with
a strawman patch for this.
However, while this will fix relative-timed queues, there will be
lurking bugs elsewhere. These don't even need to be in Java: perhaps
there is code elsewhere that checks filesystem timestamps. That's not
even unusual. There's cron, there's make, and any number of other
things. Maybe such things will be mission-critical.
So we can't say to people that it's OK to move the system clock
backwards. The best we can say is that it won't cause relative-timed
queues to malfunction. And the best advice remains "Don't do that."
Andrew.
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