You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@hbase.apache.org by "Guanghao Zhang (Jira)" <ji...@apache.org> on 2020/06/15 06:36:00 UTC
[jira] [Comment Edited] (HBASE-24558) Classic (ZK-based)
distributed WAL splitter is inscrutable in operation
[ https://issues.apache.org/jira/browse/HBASE-24558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17135464#comment-17135464 ]
Guanghao Zhang edited comment on HBASE-24558 at 6/15/20, 6:35 AM:
------------------------------------------------------------------
Some experience from our big production cluster, 200+ RS, version is based on 0.98. When hdfs NN failure or zk failure, it will cause a lot of regionservers abort and start failover. Too many failover brings too many pressure to HDFS and ZK, even make the failover hang forever. The worse thing is that hdfs/zk failure caused failover "hurt" hdfs/zk again...... So we have to only restart 10 RegionServer to take the failover job and stop other RegionServers. If the failover speed is ok, then restart 10 more regionservers to take the split work. Cannot start 200+ regionserver to do all the split work at the same time...... And there already some issues to fix these stuffs, such as HBASE-19290, HBASE-19358 and HBASE-21588. I thought they are helpful.
was (Author: zghaobac):
Some experience from our big production cluster, 200+ RS, version is based on 0.98. When hdfs NN failure or zk failure, it will cause a lot of regionservers abort and start failover. Too many failover brings too many a lot of pressure to HDFS and ZK, even make the failover hang forever. The worse thing is that hdfs/zk failure caused failover "hurt" hdfs/zk again...... So we have to only restart 10 RegionServer to take the failover job and stop other RegionServers. If the failover speed is ok, then restart 10 more regionservers to take the split work. Cannot start 200+ regionserver to do all the split work at the same time...... And there already some issues to fix these stuffs, such as HBASE-19290, HBASE-19358 and HBASE-21588. I thought they are helpful.
> Classic (ZK-based) distributed WAL splitter is inscrutable in operation
> -----------------------------------------------------------------------
>
> Key: HBASE-24558
> URL: https://issues.apache.org/jira/browse/HBASE-24558
> Project: HBase
> Issue Type: Bug
> Components: MTTR
> Reporter: Michael Stack
> Priority: Major
>
> 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:
> {code}$ echo "ls /hbase/splitWAL" | hbase -Djute.maxbuffer=10000000 org.apache.hadoop.hbase.zookeeper.ZKMainServer | sed -e 's/, /\n/g'|wc{code}
> 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:
> {code}$ hdfs dfs -lsr /hbase/WALs/*|wc{code}
> 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 {code}HBASE_SPLIT_WAL_MAX_SPLITTER = "hbase.regionserver.wal.max.splitters"{code} which is {code}
> public static final int DEFAULT_HBASE_SPLIT_WAL_MAX_SPLITTER = 2; {code} 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:
> {code}
> 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
> {code}
--
This message was sent by Atlassian Jira
(v8.3.4#803005)