Multiple periodic scripts sleep for a random amount of time in order to mitigate the thundering herd problem. This is bad, because the sum of multiple uniformly distributed random variables approaches a normal distribution, so the problem isn't mitigated as effectively as it would be with a single sleep. This change creates a single configurable anticongestion sleep. periodic will only sleep if at least one script requires it, and it will never sleep more than once per invocation. It also won't sleep if periodic was run interactively, fixing an unrelated longstanding bug. PR: 217055 PR: 210188 Reviewed by: cy MFC after: 3 weeks Differential Revision: https://reviews.freebsd.org/D10211 |
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Makefile | ||
Makefile.depend | ||
periodic.8 | ||
periodic.sh |