Add jitter option for backoff strategies

[rasviitanen]

Is your feature request related to a problem? Please describe.
When executing many requests with a fixed backoff strategy, it's possible that requests will timeout and be retried simultaneously. If the cause for the the timeout was due to "competition", it's likely that the requests will continue to compete and timeouts will continue to happen. To make this less likely, I would like to "spread" requests out over an interval instead.

I.e. I would like the ability to go from this:

To this:

Describe the solution you'd like
I would like to add the possibility of adding a jitter to backoff strategies, such that retries are less likely to occur at the same time.
The jitter would pick a random number between a backoff interval instead of picking a fixed duration.

Additional context
The figures above are from this blog post, which describes the problem in greater detail: https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/

[davidpdrsn]

Sounds good to me!

[pronebird]

There is another aspect of adding jitter which is to prevent fingerprinting the client and potential identification. When something repeats with certain interval, it can be traced and identified. In the past we used to implement jitter this way, so providing a fraction it was possible to swing the delay in either direction by certain %. The implementation should also make sure that max_delay doesn't clip the jitter and that the jitter is applied to max_delay if it's reached.

[dnlsndr]

Is there any progress here? With your OK I'd create a PR for this, orienting myself at the article posted above.