It's probably not relevant, but we have seen time "run backwards" on multi-core systems using AMD processors.

Was this using Time::HiRes on a Windows system? If so, I know how that can happen, and I don't think it is constrained to AMD processors, though I seem to remember seeing that Intel have addressed the underlying problem on their latest chips.

For my purposes, I'll be probably be using a time value limited to milliseconds anyway, but thanks for the heads up.

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In reply to Re^2: Generate a unique ID by BrowserUk
in thread Generate a unique ID by BrowserUk

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