[narwhal adpater] Add backoff mechanism to consensus adapter #3548
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
asonnino
approved these changes
Jul 28, 2022
| @@ -178,14 +189,34 @@ impl ConsensusAdapter { | |||
| // certificate will be sequenced. So the best we can do is to set a timer and notify the | |||
| // client to retry if we timeout without hearing back from consensus (this module does not | |||
| // handle retries). The best timeout value depends on the consensus protocol. | |||
| match timeout(self.max_delay, waiter.wait_for_result()).await { | |||
| let back_off_delay = | |||
| self.max_delay + Duration::from_millis(self.delay_ms.load(Ordering::Relaxed)); | |||
There was a problem hiding this comment.
should we rename max_delay to min_delay?
huitseeker
approved these changes
Jul 28, 2022
There was a problem hiding this comment.
The PR is great on direction!
- Can we log this periodically at DEBUG? Draw a normalized random float, log if it's less than .001 kinda thing?
- This contains magic constants, in particular the 1/2 value for the proportional gain. I would encourage you to declare it as such in a visible way, one that stands out from the computational detail of using hundreds.
- It may be useful to call out we're doing proportional control, for the future dev looking at this.
- Nit: It would be good to document on the
max_delayfield that it will be involved in clamping the delay variable after each adjustment.
gdanezis
force-pushed
the
adapter-backoff
branch
from
34650c8 to
e46d7e5
Compare
tharbert
pushed a commit
that referenced
this pull request
Aug 5, 2022
* Add back-off mechanism to consensus adopter (both certs and fragments) * Added more clear constants and function Co-authored-by: George Danezis <george@danez.is>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
We add a mechanism to estimate the average delay in consensus (using a weighted average with weight 1/2 is the last sequenced message / timeout) and then adapt the time we wait for a message to get sequenced to be the average delay + the max delay (instead of just the max delay). This avoids the churn of constant timeouts + re-submissions at times when consensus is already slow.