Details
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Bug
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Status: Resolved
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Blocker
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Resolution: Fixed
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3.0.0-alpha-1
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None
Description
Looks like the region server responses are being processed incorrectly in places allowing te region to be opened on two servers.
- The region server report handling in procedures should check which server is reporting.
- Also although I didn't check (and it isn't implicated in this bug), RS must check in OPEN that it's actually the correct RS master sent open to (w.r.t. start timestamp)
This was previosuly "mitigated" by master killing the RS with incorrect reports, but due to race conditions with reports and assignment the kill was replaced with a warning, so now this condition persists.
Regardless, the kill approach is not a good fix because there's still a window when a region can be opened on two servers.
A region is being opened by server_48c. The server dies, and we process the retry correctly (retry=3 because 2 previous similar open failures were processed correctly).
We start opening it on server_1aa now.
2019-01-28 18:12:09,862 INFO [KeepAlivePEWorker-104] assignment.RegionStateStore: pid=4915 updating hbase:meta row=8be2a423b16471b9417f0f7de04281c6, regionState=ABNORMALLY_CLOSED 2019-01-28 18:12:09,862 INFO [KeepAlivePEWorker-104] procedure.ServerCrashProcedure: pid=11944, state=RUNNABLE:SERVER_CRASH_ASSIGN, hasLock=true; ServerCrashProcedure server=server_48c,17020,1548726406632, splitWal=true, meta=false found RIT pid=4915, ppid=7, state=WAITING:REGION_STATE_TRANSITION_CONFIRM_OPENED, hasLock=true; TransitRegionStateProcedure table=table, region=8be2a423b16471b9417f0f7de04281c6, ASSIGN; rit=OPENING, location=server_48c,17020,1548726406632, table=table, region=8be2a423b16471b9417f0f7de04281c6 2019-01-28 18:12:10,778 INFO [KeepAlivePEWorker-80] assignment.TransitRegionStateProcedure: Retry=3 of max=2147483647; pid=4915, ppid=7, state=RUNNABLE:REGION_STATE_TRANSITION_CONFIRM_OPENED, hasLock=true; TransitRegionStateProcedure table=table, region=8be2a423b16471b9417f0f7de04281c6, ASSIGN; rit=ABNORMALLY_CLOSED, location=null ... 2019-01-28 18:12:10,902 INFO [KeepAlivePEWorker-80] assignment.TransitRegionStateProcedure: Starting pid=4915, ppid=7, state=RUNNABLE:REGION_STATE_TRANSITION_GET_ASSIGN_CANDIDATE, hasLock=true; TransitRegionStateProcedure table=table, region=8be2a423b16471b9417f0f7de04281c6, ASSIGN; rit=ABNORMALLY_CLOSED, location=null; forceNewPlan=true, retain=false 2019-01-28 18:12:11,114 INFO [PEWorker-7] assignment.RegionStateStore: pid=4915 updating hbase:meta row=8be2a423b16471b9417f0f7de04281c6, regionState=OPENING, regionLocation=server_1aa,17020,1548727658713
However, we get the remote procedure failure from 48c after we've already started that.
It actually tried to open on the restarted RS, which makes me wonder if this is safe also w.r.t. other races - what if RS already initialized and didn't error out?
Need to check if we verify the start code expected by master on RS when opening.
2019-01-28 18:12:12,179 WARN [RSProcedureDispatcher-pool4-t362] assignment.RegionRemoteProcedureBase: The remote operation pid=11050, ppid=4915, state=SUCCESS, hasLock=false; org.apache.hadoop.hbase.master.assignment.OpenRegionProcedure for region {ENCODED => 8be2a423b16471b9417f0f7de04281c6 ... to server server_48c,17020,1548726406632 failed
org.apache.hadoop.hbase.ipc.ServerNotRunningYetException: org.apache.hadoop.hbase.ipc.ServerNotRunningYetException: Server server_48c,17020,1548727752747 is not running yet
2019-01-28 18:12:12,179 WARN [RSProcedureDispatcher-pool4-t362] procedure.RSProcedureDispatcher: server server_48c,17020,1548726406632 is not up for a while; try a new one
Without any other reason (at least logged), the RIT immediately retries again and chooses a new candidate. It then retries again and goes to the new 48c, but that's unrelated.
2019-01-28 18:12:12,289 INFO [KeepAlivePEWorker-100] assignment.TransitRegionStateProcedure: Retry=4 of max=2147483647; pid=4915, ppid=7, state=RUNNABLE:REGION_STATE_TRANSITION_CONFIRM_OPENED, hasLock=true; TransitRegionStateProcedure table=table, region=8be2a423b16471b9417f0f7de04281c6, ASSIGN; rit=OPENING, location=server_1aa,17020,1548727658713 ... 2019-01-28 18:12:12,668 INFO [PEWorker-9] assignment.RegionStateStore: pid=4915 updating hbase:meta row=8be2a423b16471b9417f0f7de04281c6, regionState=OPENING, regionLocation=server_fd3,17020,1548727536972 .... 2019-01-28 18:26:29,480 INFO [KeepAlivePEWorker-154] assignment.RegionStateStore: pid=4915 updating hbase:meta row=8be2a423b16471b9417f0f7de04281c6, regionState=OPENING, regionLocation=server_48c,17020,1548727752747
What does happen though is that 1aa, that never got a chance to respond at the time that the RIT erroneously retried above, finishes opening the region - which master ignores
2019-01-28 18:27:42,424 WARN [RpcServer.default.FPBQ.Fifo.handler=29,queue=4,port=17000] assignment.TransitRegionStateProcedure: Received report OPENED transition from server_1aa,17020,1548727658713 for rit=OPENING, location=server_48c,17020,1548727752747, table=table, region=8be2a423b16471b9417f0f7de04281c6, pid=4915 but the region is not on it, should be a retry, ignore
And starts spamming these warnings until finally the region is open in two places.
2019-01-28 18:27:45,500 WARN [RpcServer.default.FPBQ.Fifo.handler=42,queue=2,port=17000] assignment.AssignmentManager: rit=OPENING, location=server_48c,17020,1548727752747, table=table, region=8be2a423b16471b9417f0f7de04281c6 reported OPEN on server=server_1aa,17020,1548727658713 but state has otherwise ... 2019-01-28 18:51:21,197 WARN [RpcServer.default.FPBQ.Fifo.handler=10,queue=0,port=17000] assignment.AssignmentManager: rit=OPEN, location=server_48c,17020,1548727752747, table=table, region=8be2a423b16471b9417f0f7de04281c6 reported OPEN on server=server_1aa,17020,1548727658713 but state has otherwise
This can result in data loss.
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