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From Stack <st...@duboce.net>
Subject Re: servlet container (embedded jetty)
Date Fri, 23 Jul 2010 15:43:43 GMT
On Fri, Jul 23, 2010 at 8:16 AM, Mark Laffoon
<mlaffoon@semanticresearch.com> wrote:
> I have a couple noobish questions about the servlet container.
> 1. As I understand it from reading docs and poking around in the code
> hadoop and hbase both use an embedded jetty instance to host their admin
> pages.


> 2. If I have hadoop master and hbase master running on the same machine,
> does that mean I have two jetty instances instantiated?


> 2a. What hadoop and hbase processes use an embedded jetty? Obviously
> namenode, hbase master, and jobtracker. What about regionserver,
> tasktracker?

The regionserver yes, the tasktracker does too at least to transfer
files during MR (last I checked).  The datanode doesn't have an

> 3. Any idea what the approximate footprint of an embedded jetty instance
> is?

Guessing, I'd say its "small"

> 4. If I have a servlet container (jetty, tomcat, whatever) running on the
> machine for other reasons, how tough is it to get hadoop and hbase to use
> it instead of the embedded jetty?

We've not done the WAR packaging.  The pieces are all there -- a
web.xml, etc., see hbase-webapps when you download a binary -- so
shouldn't be hard bundling them up.  Hard  part, as for any WAR, is
configuring it.  HBase/Hadoop config is in the conf directory.  You'd
need to get this conf on the webapp CLASSPATH so it was pointing at
proper cluster.

Historically, IIUC hadoop/hbase doesn't go all the way and make a WAR
because wants to ship w/ precompiled jsps... so on deploy you can get
away w/ JRE rather than JDK (Not so sure how this holds up any more).

> This boils down to: I'm going to have various processes using a servlet
> container on my servers. Should I worry about trying to share the same
> container across all the hadoop/hbase processes as well?

Unless a compelling reason, I'd say avoid the unification.
Hadoop/HBase are non-standard in their use of java technologies.
You'll be surprised at every turn.  It'd be time sink for little

Others might have different opinions.


> Thanks,
> Mark

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