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https://issues.apache.org/jira/browse/BOOKKEEPER-220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268940#comment-13268940
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Flavio Junqueira commented on BOOKKEEPER-220:
---------------------------------------------
bq. The major problem that I see is synchronizing all the instances of the ML
running on different boxes to decide which ledgers can be deleted.
Here is a thought. Each ML has a single "master" (the writer). The readers
simply update atomically a record in the metadata store (same record for all
readers) with the latest value of the marker up to which they have consumed.
The master is responsible for periodically checking this value and trimming the
log.
bq. the goal we have is to build something like a persistent log appender, with
multiple persistent reader marks that can be failed over to other servers when
crashing/rebalancing.
An alternative to the approach above is to have one record per reader, so that
you have persistent per reader markers and the master reads them all and picks
the smallest.
> Managed Ledger proposal
> -----------------------
>
> Key: BOOKKEEPER-220
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-220
> Project: Bookkeeper
> Issue Type: New Feature
> Components: bookkeeper-client
> Reporter: Matteo Merli
> Assignee: Matteo Merli
>
> The ManagedLedger design is based on our need to manage a set of ledgers,
> with a single writer (at any point in time) and a set on consumers that read
> entries from it.
> The ManagedLedger also takes care of periodically closing ledgers to have a
> "reasonable" sized sets of ledgers that can individually deleted when no more
> needed.
> I've put on github the interface proposal (along with an early WIP
> implementation)
> http://github.com/merlimat/managed-ledger
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