nickva commented on issue #4639: URL: https://github.com/apache/couchdb/issues/4639#issuecomment-1591810915
@jdai1 no problem at all, thanks for reaching out. The `max_backoff` error indicates that some replicator API request was throttled too much and it exceeded a max retry interval before the job crashes and restarts. Those errors are usually emitted if a [429 error code](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/429) is returned from an HTTP API endpoint. Replication jobs would retry individual requests with an exponential backoff, and in the case of 429 errors it will use the [AIMD](https://en.wikipedia.org/wiki/Additive_increase/multiplicative_decrease) - additive increase, multiplicative decrease algorithm, similar to TCP to try to match the throttling rate. But, there is a limit to those failures as well, and if those requests keep getting throttled, it will crash the whole job, and restart it with a simpler configuration. It will apply these setting to those jobs: ``` [ {checkpoint_interval, 5000}, {worker_processes, 2}, {worker_batch_size, 100}, {http_connections, 5} ] ``` and re-schedule the job to run again. Even if the replication jobs will keep crashing (they are in the `crashing` state), they should still be restarting from time to time, trying as hard as they can to make some progress. So, to summarize, individual replication API requests are retried on failure, and then the whole replication job is continuously restarted as well. See the advanced replication [guide](https://docs.couchdb.org/en/stable/replication/replicator.html#replication-states) for more info about the various job states. The suggestion is to then use some settings closer those lower capacity setting when replicating to/from those endpoints (not sure which on of your endpoint is throttled, source, target or both). -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
