[jira] [Updated] (BOOKKEEPER-848) Use volatile for lastAddConfirmed

["Matteo Merli (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/BOOKKEEPER-848?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Matteo Merli updated BOOKKEEPER-848:
------------------------------------
    Attachment: 0001-BOOKKEEPER-848-Use-volatile-for-lastAddConfirmed.patch

> Use volatile for lastAddConfirmed
> ---------------------------------
>
>                 Key: BOOKKEEPER-848
>                 URL: https://issues.apache.org/jira/browse/BOOKKEEPER-848
>             Project: Bookkeeper
>          Issue Type: Bug
>    Affects Versions: 4.3.0
>            Reporter: Matteo Merli
>            Assignee: Matteo Merli
>            Priority: Minor
>             Fix For: 4.4.0
>
>         Attachments: 0001-BOOKKEEPER-848-Use-volatile-for-lastAddConfirmed.patch
>
>
> LastAddConfirmed in LedgerHandle is updated when an entry is persisted successfully. 
> When sending a new entry, the most recent lastAddConfirmed is sent along. The reason is to start with a reasonable (confirmed) entryId when doing ledger recovery, by reading all entries from lastAddConfirmed until a NoEntryException is reached. 
> If lastAddConfirmed updates are not visible to the thread that is writing new entries, new entries will carrie an older lastAddConfirmed value, and recovering the ledger will requiring reading one-by-one many entries.
> When writing several thousand of entries per sec, the lastAddConfirmed can lag behind a lot from the real last entry.
> We should use volatile, to ensure writing thread sees the updated version.



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