[HBASE-7011] log rolling and cache flushing should be able to proceed in parallel

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Assignee: Unassigned
• Reporter: Kannan Muthukkaruppan
• Created: 18/Oct/12 22:22
• Updated: 14/Jun/22 22:08
• Resolved: 14/Jun/22 22:08

Description

Today, during a memstore flush (snapshot of memstore + flushing to disk), log rolling cannot happen. This seems like a bad design, and an unnecessary restriction.

Possible reasons cited for this in code are:
maintenance of the lastSeqWritten map.
(ii) writing a "completed-cache-flush" marker into the same log before the roll.

It seems that we can implement a new design for to avoid holding the lock for the entire duration of the flush. And the motivation for (ii) is not even clear. We should reason this out, and make sure we can relax the restriction. [See related discussion in HBASE-6980.]

Issue Links

• is related to: HBASE-7329 remove flush-related records from WAL and make locking more granular