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From "Joshua McKenzie (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6992) Bootstrap on vnodes clusters can cause stampeding/storm behavior
Date Fri, 11 Dec 2015 17:04:11 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6992?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15053024#comment-15053024
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Joshua McKenzie commented on CASSANDRA-6992:
--------------------------------------------

Yuki was out this past week. Since this is an improvement for 3.2 there's really no rush to
commit (other than atrophy).

> Bootstrap on vnodes clusters can cause stampeding/storm behavior
> ----------------------------------------------------------------
>
>                 Key: CASSANDRA-6992
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6992
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Coordination, Streaming and Messaging
>         Environment: Various vnodes-enabled clusters in EC2, m1.xlarge and hi1.4xlarge,
~3000-8000 tokens.
>            Reporter: Rick Branson
>            Assignee: Paulo Motta
>            Priority: Minor
>              Labels: dense-storage
>             Fix For: 3.2
>
>
> Assuming this is an issue with vnodes clusters because SSTableReader#getPositionsForRanges
is more expensive to compute with 256x the ranges, but could be wrong. On even well-provisioned
hosts, this can cause a severe spike in network throughput & CPU utilization from a storm
of flushes, which impacts long-tail times pretty badly. On weaker hosts (like m1.xlarge with
~500GB of data), it can result in minutes of churn while the node gets through StreamOut#createPendingFiles.
This *might* be better in 2.0, but it's probably still reproducible because the bootstrapping
node sends out all of it's streaming requests at once. 
> I'm thinking that this could be staggered at the bootstrapping node to avoid the simultaneous
spike across the whole cluster. Not sure on how to stagger it besides something very naive
like one-at-a-time with a pause. Maybe this should also be throttled in StreamOut#createPendingFiles
on the out-streaming host? Any thoughts?
> From the stack dump of one of our weaker nodes that was struggling for a few minutes
just starting the StreamOut:
> "MiscStage:1" daemon prio=10 tid=0x000000000292f000 nid=0x688 runnable [0x00007f7b03df6000]
>    java.lang.Thread.State: RUNNABLE
>         at org.apache.cassandra.utils.ByteBufferUtil.readShortLength(ByteBufferUtil.java:361)
>         at org.apache.cassandra.utils.ByteBufferUtil.readWithShortLength(ByteBufferUtil.java:371)
>         at org.apache.cassandra.io.sstable.IndexHelper$IndexInfo.deserialize(IndexHelper.java:187)
>         at org.apache.cassandra.db.RowIndexEntry$Serializer.deserialize(RowIndexEntry.java:125)
>         at org.apache.cassandra.io.sstable.SSTableReader.getPosition(SSTableReader.java:889)
>         at org.apache.cassandra.io.sstable.SSTableReader.getPosition(SSTableReader.java:790)
>         at org.apache.cassandra.io.sstable.SSTableReader.getPositionsForRanges(SSTableReader.java:730)
>         at org.apache.cassandra.streaming.StreamOut.createPendingFiles(StreamOut.java:172)
>         at org.apache.cassandra.streaming.StreamOut.transferSSTables(StreamOut.java:157)
>         at org.apache.cassandra.streaming.StreamOut.transferRanges(StreamOut.java:148)
>         at org.apache.cassandra.streaming.StreamOut.transferRanges(StreamOut.java:116)
>         at org.apache.cassandra.streaming.StreamRequestVerbHandler.doVerb(StreamRequestVerbHandler.java:44)
>         at org.apache.cassandra.net.MessageDeliveryTask.run(MessageDeliveryTask.java:56)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
>         at java.lang.Thread.run(Thread.java:662)



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