[jira] [Created] (CASSANDRA-10821) OOM Killer terminates Cassandra when Compactions use too much memory then won't restart

["Thom Bartold (JIRA)" <ji...@apache.org>]

Thom Bartold created CASSANDRA-10821:
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             Summary: OOM Killer terminates Cassandra when Compactions use too much memory then won't restart
                 Key: CASSANDRA-10821
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10821
             Project: Cassandra
          Issue Type: Bug
          Components: Compaction
         Environment: EC2 32 x i2.xlarge split between us-east-1a,c and us-west 2a,b

Linux  4.1.10-17.31.amzn1.x86_64 #1 SMP Sat Oct 24 01:31:37 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Java(TM) SE Runtime Environment (build 1.8.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)

Cassandra version: 2.2.3

            Reporter: Thom Bartold


We were writing to the DB from EC2 instances in us-east-1 at a rate of about 3000 per second, replication us-east:2 us-west:2, LeveledCompaction and DeflateCompressor.

After about 48 hours some nodes had over 800 pending compactions and a few of them started getting killed for Linux OOM. Priam attempts to restart the nodes, but they fail because of corrupted saved_cahce files.

Loading has finished, and the cluster is mostly idle, but 6 of the nodes were killed again last night by OOM.

This is the log message where the node won't restart:

ERROR [main] 2015-12-05 13:59:13,754 CassandraDaemon.java:635 - Detected unreadable sstables /media/ephemeral0/cassandra/saved_caches/KeyCache-ca.db, please check NEWS.txt and ensure that you have upgraded through all required intermediate versions, running upgradesstables

This is the dmesg where the node is terminated:

[360803.234422] Out of memory: Kill process 10809 (java) score 949 or sacrifice child
[360803.237544] Killed process 10809 (java) total-vm:438484092kB, anon-rss:29228012kB, file-rss:107576kB

This is what Compaction Stats look like currently:

pending tasks: 1096
                                     id   compaction type          keyspace      table    completed          total    unit   progress
   93eb3200-9b58-11e5-b9f1-ffef1041ec45        Compaction   overlordpreprod   document   8670748796   839129219651   bytes      1.03%
                                               Compaction            system      hints           30     1921326518   bytes      0.00%
Active compaction remaining time :  27h33m47s

Only 6 of the 32 nodes have compactions pending, and all on the order of 1000.



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