[HBASE-5568] Multi concurrent flushcache() for one region could cause data loss

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.94.0, 0.95.0
• Component/s: regionserver
• Hadoop Flags: Reviewed
• Assignee: Chunhui Shen
• Reporter: Chunhui Shen
• Created: 13/Mar/12 04:03
• Updated: 26/Feb/13 08:12
• Resolved: 19/Mar/12 22:23

Description

We could call HRegion#flushcache() concurrently now through HRegionServer#splitRegion or HRegionServer#flushRegion by HBaseAdmin.
However, we find if HRegion#internalFlushcache() is called concurrently by multi thread, HRegion.memstoreSize will be calculated wrong.
At the end of HRegion#internalFlushcache(), we will do this.addAndGetGlobalMemstoreSize(-flushsize), but the flushsize may not the actual memsize which flushed to hdfs. It cause HRegion.memstoreSize is negative and prevent next flush if we close this region.

Logs in RS for region e9d827913a056e696c39bc569ea3

2012-03-11 16:31:36,690 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Started memstore flush for writetest1,,1331454657410.e9d827913a056e696c39bc569ea3
f99f., current region memstore size 128.0m
2012-03-11 16:31:37,999 INFO org.apache.hadoop.hbase.regionserver.Store: Added hdfs://dw74.kgb.sqa.cm4:9700/hbase-func1/writetest1/e9d827913a056e696c39bc569e
a3f99f/cf1/8162481165586107427, entries=153106, sequenceid=619316544, memsize=59.6m, filesize=31.2m
2012-03-11 16:31:38,830 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Started memstore flush for writetest1,,1331454657410.e9d827913a056e696c39bc569ea3
f99f., current region memstore size 134.8m
2012-03-11 16:31:39,458 INFO org.apache.hadoop.hbase.regionserver.Store: Added hdfs://dw74.kgb.sqa.cm4:9700/hbase-func1/writetest1/e9d827913a056e696c39bc569e
a3f99f/cf2/3425971951499794221, entries=230183, sequenceid=619316544, memsize=68.5m, filesize=26.6m
2012-03-11 16:31:39,459 INFO org.apache.hadoop.hbase.regionserver.HRegion: Finished memstore flush of ~128.1m for region writetest1,,1331454657410.e9d827913a
056e696c39bc569ea3f99f. in 2769ms, sequenceid=619316544, compaction requested=false
2012-03-11 16:31:39,459 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Started memstore flush for writetest1,,1331454657410.e9d827913a056e696c39bc569ea3
f99f., current region memstore size 6.8m
2012-03-11 16:31:39,529 INFO org.apache.hadoop.hbase.regionserver.Store: Added hdfs://dw74.kgb.sqa.cm4:9700/hbase-func1/writetest1/e9d827913a056e696c39bc569e
a3f99f/cf1/1811012969998104626, entries=8002, sequenceid=619332759, memsize=3.1m, filesize=1.6m
2012-03-11 16:31:39,640 INFO org.apache.hadoop.hbase.regionserver.Store: Added hdfs://dw74.kgb.sqa.cm4:9700/hbase-func1/writetest1/e9d827913a056e696c39bc569e
a3f99f/cf2/770333473623552048, entries=12231, sequenceid=619332759, memsize=3.6m, filesize=1.4m
2012-03-11 16:31:39,641 INFO org.apache.hadoop.hbase.regionserver.HRegion: Finished memstore flush of ~134.8m for region writetest1,,1331454657410.e9d827913a
056e696c39bc569ea3f99f. in 811ms, sequenceid=619332759, compaction requested=true
2012-03-11 16:31:39,707 INFO org.apache.hadoop.hbase.regionserver.Store: Added hdfs://dw74.kgb.sqa.cm4:9700/hbase-func1/writetest1/e9d827913a056e696c39bc569e
a3f99f/cf1/5656568849587368557, entries=119, sequenceid=619332979, memsize=47.4k, filesize=25.6k
2012-03-11 16:31:39,775 INFO org.apache.hadoop.hbase.regionserver.Store: Added hdfs://dw74.kgb.sqa.cm4:9700/hbase-func1/writetest1/e9d827913a056e696c39bc569e
a3f99f/cf2/794343845650987521, entries=157, sequenceid=619332979, memsize=47.8k, filesize=19.3k
2012-03-11 16:31:39,777 INFO org.apache.hadoop.hbase.regionserver.HRegion: Finished memstore flush of ~6.8m for region writetest1,,1331454657410.e9d827913a05
6e696c39bc569ea3f99f. in 318ms, sequenceid=619332979, compaction requested=true

Issue Links

• is broken by: HBASE-5199 Delete out of TTL store files before compaction selection
• is related to: HBASE-5312 Closed parent region present in Hlog.lastSeqWritten