Details
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Bug
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Status: Open
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Major
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Resolution: Unresolved
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None
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None
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None
Description
Scenario: decent sized cluster (700 nodes) and WALs backing up (TBD: A Replication Peer was in place) such that many RSs had hundreds of WALs. Next, a power outage-like event where we have to cold-start. Master comes up and files SCPs for old server instances; hundreds. SCP finds there are hundreds of WALs and dutifully asks the wal-splitter to do its job. Meantime it goes to sleep until completion (See HBASE-24545); no status in log, just loads of complaint in log about STUCK procedure worker. Operator sees a stalled master dumping into its logs the occasional split completion and STUCK procedures but thats it. Operator tries poking up in zk under '/hbase/splitWAL' to see whats up but gets a spew back of one-line listing thousands of znodes. Operator gets no indication of how we are progressing or of when all is done.
In my particular case, there were > 100k WALs backed-up. I could dig around some and could see that 40k WALs were in-flight at any one time (necessitating upping jute.maxbuffer for zk). I could do this:
$ echo "ls /hbase/splitWAL" | hbase -Djute.maxbuffer=10000000 org.apache.hadoop.hbase.zookeeper.ZKMainServer | sed -e 's/, /\n/g'|wc
but it didn't help much as new WALs got added to the backlog. I could do the below but it didn't help when WAL count > 100k:
$ hdfs dfs -lsr /hbase/WALs/*|wc
Is the count here all the WALs that need splitting (yes, I think). Its less than zk count at any one time. How are they tied? Dunno.
This issue is about improving visibility in our distributed wal-splitter. In particular the zk-based splitter visibility is poor (HBASE-21588 is a new splitter built on procedures that probably has similar issue). We need to have a count of overall outstanding tasks, of how long tasks are taking, and of how well distributed the job is (see below).
An aside was that I had default for
HBASE_SPLIT_WAL_MAX_SPLITTER = "hbase.regionserver.wal.max.splitters"
which is
public static final int DEFAULT_HBASE_SPLIT_WAL_MAX_SPLITTER = 2;
so in extremis, I upped the count to 10 but even then looking at random RS's they were only getting work on occasion sometimes with hours passing between split tasks as though the Master was bad at passing out the jobs: hard to tell when no view on what is going on.
Below is from log of random RS... notice how sporadically it gets split work though thousands of WALs to work on:
89 2020-06-11 04:38:40,113 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-1] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@271eba8d in 12309ms. Status = DONE 90 2020-06-11 04:38:51,445 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-0] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@6c9e0b6 in 13230ms. Status = DONE 91 2020-06-11 04:38:57,060 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-1] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@7f102aeb in 16759ms. Status = DONE 92 2020-06-11 09:17:12,762 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-0] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@28c31f7d in 1181ms. Status = DONE 93 2020-06-11 09:17:14,512 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-1] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@3ecd4959 in 2224ms. Status = DONE 94 2020-06-11 09:17:14,750 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-0] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@5a72b3ad in 1345ms. Status = DONE 95 2020-06-11 09:17:19,898 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-1] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@6af0858d in 5319ms. Status = DONE 96 2020-06-11 09:17:21,558 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-0] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@1bca0d8b in 890ms. Status = DONE 97 2020-06-11 16:12:31,676 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-1] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@50a124bc in 1193ms. Status = DONE 98 2020-06-11 16:12:34,140 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-0] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@519c681c in 2383ms. Status = DONE 99 2020-06-11 16:12:35,943 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-1] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@4a47b062 in 2278ms. Status = DONE 100 2020-06-11 16:12:36,437 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-0] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@f9bcea in 1497ms. Status = DONE 101 2020-06-11 16:12:39,953 INFO [RS_LOG_REPLAY_OPS-regionserver/ps1406:16020-1] handler.WALSplitterHandler: Worker ps1406.example.org,16020,1591849310794 done with task org.apache.hadoop.hbase.coordination.ZkSplitLogWorkerCoordination$ZkSplitTaskDetails@42d82ac4 in 914ms. Status = DONE
Attachments
Issue Links
- is related to
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HBASE-24632 Enable procedure-based log splitting as default in hbase3
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- Resolved
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- Resolved
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