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https://issues.apache.org/jira/browse/COUCHDB-3324?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15957464#comment-15957464
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ASF subversion and git services commented on COUCHDB-3324:
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Commit ddcd41954258b9a5eaa95c5ecbc6300bf9f85282 in couchdb's branch
refs/heads/63012-scheduler from [~vatamane]
[ https://git-wip-us.apache.org/repos/asf?p=couchdb.git;h=ddcd419 ]
Refactor utils into 3 modules
Over the years utils accumulated a lot of functionality. Clean up a bit by
separating it into specific modules according to semantics:
- couch_replicator_docs : Handle read and writing to replicator dbs.
It includes updating state fields, parsing options from documents, and
making sure replication VDU design document is in sync.
- couch_replicator_filters : Fetch and manipulate replication filters.
- couch_replicator_ids : Calculate replication IDs. Handles versioning and
Pretty formatting of IDs. Filtered replications using user filter functions
incorporate a filter code hash into the calculation, in that case call
couch_replicator_filters module to fetch the filter from the source.
Jira: COUCHDB-3324
> Scheduling Replicator
> ---------------------
>
> Key: COUCHDB-3324
> URL: https://issues.apache.org/jira/browse/COUCHDB-3324
> Project: CouchDB
> Issue Type: New Feature
> Reporter: Nick Vatamaniuc
>
> Improve CouchDB replicator
> * Allow running a large number of replication jobs
> * Improve API with a focus on ease of use and performance. Avoid updating
> replication document with transient state updates. Instead create a proper
> API for querying replication states. At the same time provide a compatibility
> mode to let users keep existing behavior (of getting updates in documents).
> * Improve network resource usage and performance. Multiple connection to the
> same cluster could share socket connection
> * Handle rate limiting on target and source HTTP endpoints. Let replication
> request auto-discover rate limit capacity based on a proven algorithm such as
> Additive Increase / Multiplicative Decrease feedback control loop.
> * Improve performance by avoiding repeatedly retrying failing replication
> jobs. Instead use exponential backoff.
> * Improve recovery from long (but temporary) network failure. Currently if
> replications jobs fail to start 10 times in a row they will not be retried
> anymore. This is not always desirable. In case of a long enough DNS (or other
> network) failure replication jobs will effectively stop until they are
> manually restarted.
> * Better handling of filtered replications: Failing to fetch filters could
> block couch replicator manager, lead to message queue backups and memory
> exhaustion. Also, when replication filter code changes update replication
> accordingly (replication job ID should change in that case)
> * Provide better metrics to introspect replicator behavior.
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