fix(tsm1): "snapshot in progress" error during backup #20033
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When an InfluxDB database is very busy writing new points the backup the process can fail because it can not write a new snapshot. The error is: operation timed out with error: create snapshot: snapshot in progress. This happens because InfluxDB takes almost "continuously" a snapshot from the cache caused by the high number of points ingested. The fix for this was #16627 but it was for OSS only, and was not in the code path for backups in clusters. This fix adds a skipCacheOk flag to tsdb.Engine.CreateSnapshot(). A value of true allows the backup to proceed even if a cache snapshot cannot be taken. This flag is set to true in tsm1.Engine.Backup(), the OSS backup code path and in tsdb.Shard.CreateSnapshot(), the cluster backup code path. This flag is set to false in tsm1.Engine.Export() influxdata/plutonium#3227 (cherry picked from commit 23be20b)
This fix adds a skipCacheOk flag to tsdb.Store.CreateShardSnapshot() and tsdb.Shard.CreateSnapshot() to pass to tsdb.Engine.CreateSnapshot() A value of true allows the backup to proceed even if a cache snapshot cannot be taken. This flag is set to true in tsm1.Engine.Backup(), the OSS backup code path This flag is set to false in tsm1.Engine.Export() influxdata/plutonium#3227 (cherry picked from commit 6ec446f)
Test the skipCacheOk flag to tsdb.Shard.CreateSnapshot() and tsdb.Engine.CreateSnapshot() A value of true allows the backup to proceed even if a cache snapshot cannot be taken. influxdata/plutonium#3227 (cherry picked from commit 0dcff81)
davidby-influx
changed the title
Loop with backoff in (*Engine).CreateSnapshot() to retry (*Engine).WriteSnapshot() up to 3 times if ErrSnapshotInPrgress is returned. Then continue on no error or on SnapshotInProgress if skipCacheOk is true. influxdata/plutonium#3227
Failed to format code before commit.
dgnorton
approved these changes
Nov 17, 2020
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fix(tsm1): "snapshot in progress" error during backup
Cherry-pick of commits
This requires a matching change to Plutonium PRC protobuf structures in order to link with Plutonium
Fixes InfluxDb side of issue