[ https://issues.apache.org/jira/browse/BOOKKEEPER-670?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sijie Guo resolved BOOKKEEPER-670. ---------------------------------- Resolution: Fixed all the long poll changes are merged. > Longpoll Read & Piggyback Support > --------------------------------- > > Key: BOOKKEEPER-670 > URL: https://issues.apache.org/jira/browse/BOOKKEEPER-670 > Project: Bookkeeper > Issue Type: New Feature > Components: bookkeeper-client, bookkeeper-server > Reporter: Sijie Guo > Assignee: Sijie Guo > Fix For: 4.5.0 > > Attachments: LACNotificationonBookKeeper.pdf > > > LastAddConfirmed (LAC) is a hint entry id carried on each entry written by a > ledger writer, which indicates that all the entries before LAC have already > acknowledged by the writer. So the reader is safe to read all the entries > written before LAC. > Currently a bookkeeper reader doesn’t sync LAC with the bookkeeper writer. So > a bookkeeper reader has to read LAC (aka LedgerHandle#readLastConfirmed) > before getting the latest entries written by the writer. > Such polling behavior results in poor performance: > * Delay on reading entries if we are setting a larger polling interval. > ** ReadLastConfirm needs to wait all the responses from all bookies in last > ensemble. This constraint is required for Ledger Recovery Procedure, but not > for the reader just needs to know latest LAC. > * It might Introduce useless polling loads to bookie servers if we are > setting a smaller polling interval. > A notification mechanism is good to reduce round-trips that a reader spent on > polling LAC. -- This message was sent by Atlassian JIRA (v6.4.14#64029)