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Posted to commits@cassandra.apache.org by "Sergey Lapukhov (JIRA)" <ji...@apache.org> on 2017/11/23 16:53:00 UTC
[jira] [Created] (CASSANDRA-14069) Node stopped serving write
requests when a table has a lot of sstables
Sergey Lapukhov created CASSANDRA-14069:
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Summary: Node stopped serving write requests when a table has a lot of sstables
Key: CASSANDRA-14069
URL: https://issues.apache.org/jira/browse/CASSANDRA-14069
Project: Cassandra
Issue Type: Bug
Components: Core
Reporter: Sergey Lapukhov
Attachments: create.cql, stack.txt
Cluster was flooded with SSTables. A table had ~20000 sstables. Write requests started failing.
Steps to reproduce:
* Create cluster with 3 nodes
* Specify
{{memtable_heap_space_in_mb: 10}}
in cassandra.yaml
* Create table standard1 in keyspace1 (for the cassandra-stress tool) with the script [^create.cql]. Please note
{{ compaction = {'class': 'SizeTieredCompactionStrategy', 'enabled': 'false'} }}
- i.e. node will not perform compaction.
* Populate node with data:
{{cassandra-stress write n=1000000000 -node 127.0.0.1}}
* After node was populated, put both read and write pressure on it:
{{cassandra-stress read n=1000000000 -node 127.0.0.1
cassandra-stress write n=1000000000 -node 127.0.0.1}}
* While still under pressure, enable LeveledCompactionStrategy
{{echo "ALTER TABLE keyspace1.standard1 WITH compaction = { 'class' : 'LeveledCompactionStrategy', 'sstable_size_in_mb' : 1 }; DESC keyspace1.standard1; exit" | bin/cqlsh;}}
*Results:*
Write requests failing, read requests still processed.
'bin/nodetool cfstats' and 'bin/nodetool compactionstats' commands hanging, if issued from the node running cassandra-stress tool.
If issued from another node:
{{$ bin/nodetool cfstats
...
Table: standard1
SSTable count: 22637
SSTables in each level: [22651/4, 0, 0, 0, 0, 0, 0, 0, 0]
...}}
{{$ bin/nodetool compactionstats
pending tasks: 12656
id compaction type keyspace table completed total unit progress
935bbc00-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 standard1 59556014 59557860 bytes 100.00%
a29ee660-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 standard1 80432114 742151655 bytes 10.84%
9766e400-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 standard1 58891604 58893215 bytes 100.00%
9cdc9880-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 standard1 20289449 20290800 bytes 99.99%
90f98910-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 standard1 59689824 59695545 bytes 99.99%
986ede20-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 standard1 40598594 40598820 bytes 100.00%
9cd322a0-d03b-11e7-a47d-2b44293495b8 Compaction keyspace1 standard1 60756739 60766660 bytes 99.98%
}}
Special note about 'bin/nodetool compactionstats' - picture above is quite typical for this issue. I.e. compaction tasks manage to make it through, but hinder near the full completion (around 99.9 %).
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