Run Nutch In Eclipse on Linux and Windows nutch version 1.0

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Tested with

Before you start

Setting up Nutch to run into Eclipse can be tricky, and most of the time it is much faster if you edit Nutch in Eclipse but run the scripts from the command line (my 2 cents). However, it's very useful to be able to debug Nutch in Eclipse. Sometimes examining the logs (logs/hadoop.log) is quicker to debug a problem.

Steps

For Windows Users

If you are running Windows (tested on Windows XP) you must first install cygwin. Download it from http://www.cygwin.com/setup.exe

Install cygwin and set the PATH environment variable for it. You can set it from the Control Panel, System, Advanced Tab, Environment Variables and edit/add PATH.

Example PATH:

C:\Sun\SDK\bin;C:\cygwin\bin

If you run "bash" from the Windows command line (Start > Run... > cmd.exe) it should successfully run cygwin.

If you are running Eclipse on Vista, you will need to either give cygwin administrative privileges or turn off Vista's User Access Control (UAC). Otherwise Hadoop will likely complain that it cannot change a directory permission when you later run the crawler:

org.apache.hadoop.util.Shell$ExitCodeException: chmod: changing permissions of ... Permission denied

See this for more information about the UAC issue.

Install Nutch

Create a new Java Project in Eclipse

Configure Nutch

Missing org.farng and com.etranslate

Eclipse will complain about some import statements in parse-mp3 and parse-rtf plugins (30 errors in my case). Because of incompatibility with the Apache license, the .jar files that define the necessary classes were not included with the source code.

Download them here:

http://nutch.cvs.sourceforge.net/nutch/nutch/src/plugin/parse-mp3/lib/

http://nutch.cvs.sourceforge.net/nutch/nutch/src/plugin/parse-rtf/lib/

Copy the jar files into src/plugin/parse-mp3/lib and src/plugin/parse-rtf/lib/ respectively. Then add the jar files to the build path (First refresh the workspace by pressing F5. Then right-click the project folder > Build Path > Configure Build Path... Then select the Libraries tab, click "Add Jars..." and then add each .jar file individually. If that does not work, you may try clicking "Add External JARs" and the point to the two the directories above).

Two Errors with RTFParseFactory

If you are trying to build the official 1.0 release, Eclipse will complain about 2 errors regarding the RTFParseFactory (this is after adding the RTF jar file from the previous step). This problem was fixed (see NUTCH-644 and NUTCH-705) but was not included in the 1.0 official release because of licensing issues. So you will need to manually alter the code to remove these 2 build errors.

In RTFParseFactory.java:

  1. Add the following import statement: import org.apache.nutch.parse.ParseResult;

  2. Change

public Parse getParse(Content content) {

to

public ParseResult getParse(Content content) {
  1. In the getParse function, replace

return new ParseStatus(ParseStatus.FAILED,
                               ParseStatus.FAILED_EXCEPTION,
                               e.toString()).getEmptyParse(conf);

with

return new ParseStatus(ParseStatus.FAILED,
                ParseStatus.FAILED_EXCEPTION,
              e.toString()).getEmptyParseResult(content.getUrl(), getConf());
  1. In the getParse function, replace

return new ParseImpl(text,
                         new ParseData(ParseStatus.STATUS_SUCCESS,
                                       title,
                                       OutlinkExtractor.getOutlinks(text, this.conf),
                                       content.getMetadata(),
                                       metadata));

with

return ParseResult.createParseResult(content.getUrl(),
                             new ParseImpl(text,
                                     new ParseData(ParseStatus.STATUS_SUCCESS,
                                             title,
                                             OutlinkExtractor.getOutlinks(text, this.conf),
                                             content.getMetadata(),
                                             metadata)));

In TestRTFParser.java, replace

parse = new ParseUtil(conf).parseByExtensionId("parse-rtf", content);

with

parse = new ParseUtil(conf).parseByExtensionId("parse-rtf", content).get(urlString);

Once you have made these changes and saved the files, Eclipse should build with no errors.

Build Nutch

If you setup the project correctly, Eclipse will build Nutch for you into "tmp_build". See below for problems you could run into.

Create Eclipse launcher

org.apache.nutch.crawl.Crawl

urls -dir crawl -depth 3 -topN 50

-Dhadoop.log.dir=logs -Dhadoop.log.file=hadoop.log

Debug Nutch in Eclipse (not yet tested for 0.9)

Fetcher [line: 371] - run
Fetcher [line: 438] - fetch
Fetcher$FetcherThread [line: 149] - run()
Generator [line: 281] - generate
Generator$Selector [line: 119] - map
OutlinkExtractor [line: 111] - getOutlinks

If things do not work...

Yes, Nutch and Eclipse can be a difficult companionship sometimes ;-)

Java Heap Size problem

If the crawler throws an IOException exception early in the crawl (Exception in thread "main" java.io.IOException: Job failed!), check the logs/hadoop.log file for further information. If you find in hadoop.log lines similar to this:

2009-04-13 13:41:06,105 WARN  mapred.LocalJobRunner - job_local_0001
java.lang.OutOfMemoryError: Java heap space

then you should increase amount of RAM for running applications from Eclipse.

Just set it in:

Eclipse -> Window -> Preferences -> Java -> Installed JREs -> edit -> Default VM arguments

I've set mine to

-Xms5m -Xmx150m

because I have like 200MB RAM left after running all apps

-Xms (minimum ammount of RAM memory for running applications) -Xmx (maximum)

Eclipse: Cannot create project content in workspace

The nutch source code must be out of the workspace folder. My first attempt was download the code with eclipse (svn) under my workspace. When I try to create the project using existing code, eclipse don't let me do it from source code into the workspace. I use the source code out of my workspace and it work fine.

plugin dir not found

Make sure you set your plugin.folders property correct, instead of using a relative path you can use a absolute one as well in nutch-defaults.xml or may be better in nutch-site.xml

<property>
  <name>plugin.folders</name>
  <value>/home/....../nutch-0.9/src/plugin</value>

No plugins loaded during unit tests in Eclipse

During unit testing, Eclipse ignored conf/nutch-site.xml in favor of src/test/nutch-site.xml, so you might need to add the plugin directory configuration to that file as well.

NOTE: Additional note for people who want to run eclipse with latest nutch code

If you are getting following exception - org.apache.nutch.plugin.PluginRuntimeException: java.lang.ClassNotFoundException: org.apache.nutch.net.urlnormalizer.basic.BasicURLNormalizer

  1. Execute 'ant job' (which is the default) after downloading nutch through SVN
  2. Update "plugin.folders" (under nutch-default.xml) to build/plugins (where ant builds plugins)
  3. If it still fails increase your memory allocation or find a simpler website to crawl.

Unit tests work in eclipse but fail when running ant in the command line

Suppose your unit tests work perfectly in eclipse, but each and everyone fail when running ant test in the command line - including the ones you haven't modified. Check if you defined the plugin.folders property in hadoop-site.xml. In that case, try removing it from that file and adding it directly to nutch-site.xml

Run ant test again. That should have solved the problem.

If that didn't solve the problem, are you testing a plugin? If so, did you add the plugin to the list of packages in plugin\build.xml, on the test target?

classNotFound

debugging hadoop classes

Failed to get the current user's information

On Windows, if the crawler throws an exception complaining it "Failed to get the current user's information" or 'Login failed: Cannot run program "bash"', it is likely you forgot to set the PATH to point to cygwin. Open a new command line window (All Programs > Accessories > Command Prompt) and type "bash". This should start cygwin. If it doesn't, type "path" to see your path. You should see within the path the cygwin bin directory (e.g., C:\cygwin\bin). See the steps to adding this to your PATH at the top of the article under "For Windows Users". After setting the PATH, you will likely need to restart Eclipse so it will use the new PATH.

Original credits: RenaudRichardet

Updated by: Zeeshan

RunNutchInEclipse1.0 (last edited 2010-06-08 12:38:40 by jakdemir)