Hernan Romer created HBASE-30479:
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Summary: SnapshotProcedure's exclusive table lock blocks region
assignment on large tables
Key: HBASE-30479
URL: https://issues.apache.org/jira/browse/HBASE-30479
Project: HBase
Issue Type: Improvement
Components: Region Assignment, snapshots
Affects Versions: 2.6.3, 3.0.0
Reporter: Hernan Romer
Since HBASE-29386, SnapshotProcedure takes an exclusive table lock for each
state, instead of a shared lock held for the whole procedure. While a state
runs, region assignment on that table is blocked. Some states do slow work
inline: consolidating the manifest, verifying regions when the table has fewer
than 10k regions, and adding split parent regions. On a table with tens of
thousands of regions these can take minutes, and regions moved during that time
stay in transition until the snapshot finishes. We hit this in production on a
cluster with ~64k regions.
The original design used a shared lock specifically to avoid this (see
HBASE-21480). I propose going back to the shared lock with holdLock=true, and
fixing the HBASE-29386 deadlock directly by failing the snapshot in
SNAPSHOT_WRITE_SNAPSHOT_INFO when the table is neither ENABLED nor DISABLED.
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