exponential backoff

exponential backoff

Posted Feb 1, 2007 12:54 UTC (Thu) by robbe (guest, #16131)
In reply to: LCA: Andrew Tanenbaum on creating reliable systems by tjc
Parent article: LCA: Andrew Tanenbaum on creating reliable systems

Exponential backoff is a standard technique used, for example by mail
servers, in the face of transient failures: after the n-th consequitve
error, wait f * k^n seconds, then retry. Suitable values for f and k
depend on the application -- k is often 2 -> binary exponential backoff.

Example with f = 300, i.e. 5 minutes (a viable value for SMTP):

* First try ... fails
* Wait 5 minutes
* Second try ... fails
* Wait 10 minutes
* Third try ... fails
* Wait 20 minutes
* Fourth try ... fails
* Wait 40 minutes
* Fifth try ...
etc.

It would work the same for OS-component restart, of course with values
for f in the milliseconds.

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