Refactor org.apache.hadoop.mapred.StatusHttpServer

• Key: HADOOP-3824
• Type: Sub-task
• Status: Closed
• Resolution: Fixed
• Priority: Major
• Assignee: Tsz Wo (Nicholas), SZE
• Reporter: Tsz Wo (Nicholas), SZE
• Fix Version/s: 0.19.0

Description

StatusHttpServer is defined in the mapred package but it is used by hdfs classes DataNode, FSNamesystem, SecondaryNameNode.

Comments

[Tsz Wo (Nicholas), SZE]

How about we create a package org.apache.hadoop.http in core and then split StatusHttpServer to two classes, StatusHttpServer and HttpServer, where HttpServer is an abstract base class for all hadoop http server?

[stack]

Can HADOOP-2024 be addressed as part of this refactoring?

[Tsz Wo (Nicholas), SZE]

3824_20080724.patch:

• created org.apache.hadoop.http.HttpServer
• changed fields from "private" to "protected final" whenever it is possible
• changed getWebAppsPath() "private static" to "protected"
• removed makeRuntimeException(...) by using java 6 constructor

[Tsz Wo (Nicholas), SZE]

> Can HADOOP-2024 be addressed as part of this refactoring?

I changed the getWebAppsPath() header as your patch in HADOOP-2024. I also changed "StatusHttpServer.class.getClassLoader()..." to "getClass().getClassLoader()...".

[stack]

Would you consider using this version of your patch?

Only change is to the HttpServer constructor calling out to a new method named addWebapps. Its in this method that we add webapps and servlets rather than up in the constructor. Makes it so a subclass can influence whats loaded (not load some or load with different names, etc.).

Use case is something like hbase. Currently we have a duplicate of the old StatusHttpServer. We call it InfoServer down in hbase-land. Hbase has webapps like those in hadoop-core only they want just some of the webapps+servlets that hadoop-core used put up in InfoServer. We made the duplicate because we couldn't subclass old StatusHttpServer (HADOOP-2024 was attempt at getting in a patch that would make it subclassable).

Thanks for your consideration. THanks.

[Tsz Wo (Nicholas), SZE]

Sure, your change looks good.

[Tsz Wo (Nicholas), SZE]

Found a NPE in addWebapps(...) since webAppContext is null when adding servlets.

3824_20080725.patch: fix the NPE problem.

[stack]

+1 on patch. It looks good. Downloaded it and tried it. UIs came up fine. Does the 'stacks' link work for you? I was typing in http://XX.XX.XXX.XX:50070/stacks. /logLevel worked fine.

Not important nitpicks:

+ Says '+ * A mepred http server. ' on the class comment for StatusHttpServer.
+ Maybe make this protected so subclasses have access: + static class StackServlet extends HttpServlet {

[Tsz Wo (Nicholas), SZE]

3824_20080725b.patch: fixed the following problems

> + Says '+ * A mepred http server. ' on the class comment for StatusHttpServer.
oops, there is a typo

> + Maybe make this protected so subclasses have access: + static class StackServlet extends HttpServlet {
It turns out that we need to make StackServlet public. Otherwise, jetty cannot accesses it. That's why StackServlet was not working before. For the same reason, keeping StatusHttpServer and TaskGraphServlet public.

[Tsz Wo (Nicholas), SZE]

Checked the web pages manually. Everything seems working fine.

[Tsz Wo (Nicholas), SZE]

Passed tests locally, try hudson.

[Hadoop QA]

+1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12386921/3824_20080725b.patch
against trunk revision 679879.

+1 @author. The patch does not contain any @author tags.

+1 tests included. The patch appears to include 3 new or modified tests.

+1 javadoc. The javadoc tool did not generate any warning messages.

+1 javac. The applied patch does not increase the total number of javac compiler warnings.

+1 findbugs. The patch does not introduce any new Findbugs warnings.

+1 release audit. The applied patch does not increase the total number of release audit warnings.

+1 core tests. The patch passed core unit tests.

+1 contrib tests. The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2955/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2955/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2955/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2955/console

This message is automatically generated.

[Chris Douglas]

I just committed this. Thanks, Nicholas

[Hudson]

Integrated in Hadoop-trunk #581 (See http://hudson.zones.apache.org/hudson/job/Hadoop-trunk/581/)

[Tsz Wo (Nicholas), SZE]

3824_20080912_0.18.patch: for 0.18

[Tsz Wo (Nicholas), SZE]

     [exec] +1 overall.  

     [exec]     +1 @author.  The patch does not contain any @author tags.

     [exec]     +1 tests included.  The patch appears to include 3 new or modified tests.

     [exec]     +1 javadoc.  The javadoc tool did not generate any warning messages.

     [exec]     +1 javac.  The applied patch does not increase the total number of javac compiler warnings.

     [exec]     +1 findbugs.  The patch does not introduce any new Findbugs warnings.

[Tsz Wo (Nicholas), SZE]

The 0.18 patch passed all tests locally. Feel free to use it. It won't be committed to svn.