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From Chester Chen <chesterxgc...@yahoo.com>
Subject Re: Is spark context in local mode thread-safe?
Date Mon, 09 Jun 2014 23:54:22 GMT
Matei, 
If we use different Akka actors to process different user's requests, (not different threads),
is the SparkContext still safe to use for different users ? 

Yes, it would be nice to disable UI via configuration,especially when we develop locally.
We use sbt-web plugin to debug tomcat code. If we can disable the UI http Server; it would
be much simpler to handle than having two http containers to deal with. 

Chester



On Monday, June 9, 2014 4:35 PM, Matei Zaharia <matei.zaharia@gmail.com> wrote:
 


You currently can’t have multiple SparkContext objects in the same JVM, but within a SparkContext,
all of the APIs are thread-safe so you can share that context between multiple threads. The
other issue you’ll run into is that in each thread where you want to use Spark, you need
to use SparkEnv.set(env) where “env” was obtained by SparkEnv.get in the thread that created
the context. This requirement will hopefully go away soon.

Unfortunately there’s no way yet to disable the UI — feel free to open a JIRA for it,
it shouldn’t be hard to do.

Matei


On Jun 9, 2014, at 3:50 PM, DB Tsai <dbtsai@stanford.edu> wrote:

> Hi guys,
> 
> We would like to use spark hadoop api to get the first couple hundred
> lines in design time to quickly show users the file-structure/meta
> data, and the values in those lines without launching the full spark
> job in cluster.
> 
> Since we're web-based application, there will be multiple users using
> the spark hadoop api, for exmaple, sc.textFile(filePath). I wonder if
> those APIs are thread-safe in local mode (each user will have its own
> SparkContext object).
> 
> Secondly, it seems that even in local mode, the jetty UI tracker will
> be lunched. For this kind of cheap operation, having jetty UI tracker
> for each operation will be very expensive. Is there a way to disable
> this behavior?
> 
> Thanks.
> 
> Sincerely,
> 
> DB Tsai
> -------------------------------------------------------
> My Blog: https://www.dbtsai.com
> LinkedIn: https://www.linkedin.com/in/dbtsai
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