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Posted to issues@spark.apache.org by "Nicholas Chammas (JIRA)" <ji...@apache.org> on 2016/01/27 14:26:39 UTC
[jira] [Commented] (SPARK-5189) Reorganize EC2 scripts so that
nodes can be provisioned independent of Spark master
[ https://issues.apache.org/jira/browse/SPARK-5189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15119220#comment-15119220 ]
Nicholas Chammas commented on SPARK-5189:
-----------------------------------------
FWIW, I found this issue to be practically unsolvable without rewriting most of spark-ec2, so I started a new project that aims to replace spark-ec2 for most of its use cases: [Flintrock|https://github.com/nchammas/flintrock]
> Reorganize EC2 scripts so that nodes can be provisioned independent of Spark master
> -----------------------------------------------------------------------------------
>
> Key: SPARK-5189
> URL: https://issues.apache.org/jira/browse/SPARK-5189
> Project: Spark
> Issue Type: Improvement
> Components: EC2
> Reporter: Nicholas Chammas
>
> As of 1.2.0, we launch Spark clusters on EC2 by setting up the master first, then setting up all the slaves together. This includes broadcasting files from the lonely master to potentially hundreds of slaves.
> There are 2 main problems with this approach:
> # Broadcasting files from the master to all slaves using [{{copy-dir}}|https://github.com/mesos/spark-ec2/blob/branch-1.3/copy-dir.sh] (e.g. during [ephemeral-hdfs init|https://github.com/mesos/spark-ec2/blob/3a95101c70e6892a8a48cc54094adaed1458487a/ephemeral-hdfs/init.sh#L36], or during [Spark setup|https://github.com/mesos/spark-ec2/blob/3a95101c70e6892a8a48cc54094adaed1458487a/spark/setup.sh#L3]) takes a long time. This time increases as the number of slaves increases.
> I did some testing in {{us-east-1}}. This is, concretely, what the problem looks like:
> || number of slaves ({{m3.large}}) || launch time (best of 6 tries) ||
> | 1 | 8m 44s |
> | 10 | 13m 45s |
> | 25 | 22m 50s |
> | 50 | 37m 30s |
> | 75 | 51m 30s |
> | 99 | 1h 5m 30s |
> Unfortunately, I couldn't report on 100 slaves or more due to SPARK-6246, but I think the point is clear enough.
> We can extrapolate from this data that *every additional slave adds roughly 35 seconds to the launch time* (so a cluster with 100 slaves would take 1h 6m 5s to launch).
> # It's more complicated to add slaves to an existing cluster (a la [SPARK-2008]), since slaves are only configured through the master during the setup of the master itself.
> Logically, the operations we want to implement are:
> * Provision a Spark node
> * Join a node to a cluster (including an empty cluster) as either a master or a slave
> * Remove a node from a cluster
> We need our scripts to roughly be organized to match the above operations. The goals would be:
> # When launching a cluster, enable all cluster nodes to be provisioned in parallel, removing the master-to-slave file broadcast bottleneck.
> # Facilitate cluster modifications like adding or removing nodes.
> # Enable exploration of infrastructure tools like [Terraform|https://www.terraform.io/] that might simplify {{spark-ec2}} internals and perhaps even allow us to build [one tool that launches Spark clusters on several different cloud platforms|https://groups.google.com/forum/#!topic/terraform-tool/eD23GLLkfDw].
> More concretely, the modifications we need to make are:
> * Replace all occurrences of {{copy-dir}} or {{rsync}}-to-slaves with equivalent, slave-side operations.
> * Repurpose {{setup-slave.sh}} as {{provision-spark-node.sh}} and make sure it fully creates a node that can be used as either a master or slave.
> * Create a new script, {{join-to-cluster.sh}}, that takes a provisioned node, configures it as a master or slave, and joins it to a cluster.
> * Move any remaining logic in {{setup.sh}} up to {{spark_ec2.py}} and delete that script.
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