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stack commented on HBASE-2957: ------------------------------ First, are you fellas running with hdfs-895? (See HBASE-2467) We have it deployed over here. It makes a big difference. @Prakash So you are suggesting a patch that optionally allows returning to the client though WAL has not been appended. A flag in the Put would be checked somewhere around here -- http://hbase.apache.org/docs/r0.89.20100726/xref/org/apache/hadoop/hbase/regionserver/HRegion.html#1534 -- and if set, we'd skip the inline WAL append and in its place we'd just add the edit to a queue for adding the WAL out of bound with the current update? I'd guess you'd want the flag on ICV too, somewhere around here -- http://hbase.apache.org/docs/r0.89.20100726/xref/org/apache/hadoop/hbase/regionserver/HRegion.html#3046? We'd change our current 'writeToWAL' flag so rather than being a binary, that it would allow a new queue-the-edit-for-WAL-addition option? > Release row lock when waiting for wal-sync > ------------------------------------------ > > Key: HBASE-2957 > URL: https://issues.apache.org/jira/browse/HBASE-2957 > Project: HBase > Issue Type: Improvement > Components: regionserver, wal > Affects Versions: 0.20.0 > Reporter: Prakash Khemani > > Is there a reason to hold on to the row-lock while waiting for the WAL-sync > to be completed by the logSyncer thread? > I think data consistency will be guaranteed even if the following happens (a) > the row lock is held while the row is updated in memory (b) the row lock is > released after queuing the KV record for WAL-syncing (c) the log-sync system > guarantees that the log records for any given row are synced in order (d) the > HBase client only receives a success notification after the sync completes > (no change from the current state) > I think this should be a huge win. For my use case, and I am sure for others, > the handler thread spends the bulk of its row-lock critical section time > waiting for sync to complete. > Even if the log-sync system cannot guarantee the orderly completion of sync > records, the "Don't hold row lock while waiting for sync" option should be > available to HBase clients on a per request basis. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.