XWiki Development Zone » Debugging

Debugging

Last modified by Vincent Massol on 2013/12/19 15:32

There are several possibilities for debugging XWiki:

Debugging XWiki from your IDE

Debugging with Eclipse

Once you've gotten the debugger working, you'll wonder how you ever survived without it.

Complete tutorial based on M2Eclipse and WTP

Debug XWiki with Eclipse

Debug a XWiki released version

  • Follow the steps from Building In Eclipse including the optional "Import the WAR as a web project".
  • Select from the Eclipse menu Run > Debug...
  • Create a new configuration for your server
  • Hit the Debug button
  • Set breakpoints, step through code, have fun!

WTP will deploy XWiki into {workspace_location}/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/webapps/xwiki. If you suspect a change has not been deployed correctly (e.g. a change to a config file), check there to confirm.

If you are working on an XWiki plugin in a separate project in your workspace, you can ensure it is automatically deployed to XWiki's WEB-INF/lib directory when debugging. Open the project properties of the XWiki project resulting from the WAR import above, go to the J2EE Module Dependencies section, and add your plugin project.

Using Firebug when debugging a selenium test

For that you will need to install Firebug as a global extension

Remote Debugging

To perform remote debugging, start your wiki in debug mode. To do this modify the way you start your container and ensure that the following JVM parameters are passed:

-Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005

For example, for Jetty you could use the following start script:

#!/bin/sh

JETTY_HOME=.
JETTY_PORT=8080
JAVA_OPTS="-Xmx300m -Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005"

java $JAVA_OPTS -Dfile.encoding=iso-8859-1 -Djetty.port=$JETTY_PORT -Djetty.home=$JETTY_HOME -jar $JETTY_HOME/start.jar
You can also easily run Jetty in debug mode by using the jettyrun profile in the Maven build.

If you are using the Tomcat service on Windows, you should modify the JVM args with the Tomcat Service Configuration Panel. Select the Java tab and add each of the options on a separate line. For example:

-Dcatalina.home=C:\Program Files\Apache Software Foundation\Tomcat 5.5
-Dcatalina.base=C:\Program Files\Apache Software Foundation\Tomcat 5.5
-Djava.endorsed.dirs=C:\Program Files\Apache Software Foundation\Tomcat 5.5\common\endorsed
-Djava.io.tmpdir=C:\Program Files\Apache Software Foundation\Tomcat 5.5\temp
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
-Djava.util.logging.config.file=C:\Program Files\Apache Software Foundation\Tomcat 5.5\conf\logging.properties
-Xdebug
-Xnoagent
-Djava.compiler=NONE  
-Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n

Then, in your favorite IDE, open the XWiki project and run a remote debugging session, attached to the socket on port 5005. For example, if you're using IntelliJ IDEA, go to Run|Edit Configurations... and create a new Remote configuration (default parameters should be fine). Then execute it and IDEA will connect to the executing JVM. 

You can then place breakpoints in your source code.

Logging

Turning on logging inside XWiki

See the Logging page in the Admin guide.

Logging calls at the database level

You have several options:

  • Configure Hibernate to log SQL calls. To do this edit XWiki's log configuration file (see the Logging page) and change the log level from warn to trace for the following:
      <!-- Log HQL query parser activity -->
      <logger name="org.hibernate.hql.ast.AST" level="warn"/>
      <!-- Log just the SQL -->
      <logger name="org.hibernate.SQL" level="warn"/>
      <!-- Log JDBC bind parameters -->
      <logger name="org.hibernate.type" level="warn"/>
      <!-- Log schema export/update -->
      <logger name="org.hibernate.tool.hbm2ddl" level="warn"/>
      <!-- Log HQL parse trees -->
      <logger name="org.hibernate.hql" level="warn"/>
      <!-- Log cache activity -->
      <logger name="org.hibernate.cache" level="warn"/>
      <!-- Log transaction activity -->
      <logger name="org.hibernate.transaction" level="warn"/>
      <!-- Log JDBC resource acquisition -->
      <logger name="org.hibernate.jdbc" level="warn"/>
      <!-- Enable the following line if you want to track down connection leakages when using
           DriverManagerConnectionProvider -->
      <logger name="org.hibernate.connection.DriverManagerConnectionProvider" level="warn"/>
      <!-- Log prepared statement cache activity -->
      <logger name="org.hibernate.ps.PreparedStatementCache" level="warn"/>
  • Use a wrapping JDBC driver such as log4jdbc or p6spy.
  • Turn on logging in your database. The configuration is database-dependent
    • For HSQLDB. Two solutions:
      • Solution 1: Edit WEB-INF/hibernate.cfg.xml and modify the URL connection property to add hsqldb.sqllog=3, as in:
        <property name="connection.url">jdbc:hsqldb:file:${environment.permanentDirectory}/database/xwiki_db;shutdown=true;hsqldb.sqllog=3</property>
      • Solution 2: Using Byteman (See the section below for more information). For example the following rule (tested on HSQLDB 2.3.1) will log SQL statements with parameters and schema when there's more than 1 parameter:
        RULE Log SQL Statement
        CLASS org.hsqldb.Session
        METHOD executeCompiledStatement(org.hsqldb.Statement, Object[], int)
        AT ENTRY
        IF $2.length > 0
        DO traceln("SQL Statement = [" + $1.getSQL() + "], parameter 1 = [" + $2[0] + "], schema = [" + $1.getSchemaName().name + "]")
        ENDRULE

        Will give for example:

        SQL Statement = [select xwikidocum0_.XWD_ID as XWD1_0_0_, xwikidocum0_.XWD_FULLNAME as XWD2_0_0_, xwikidocum0_.XWD_NAME as XWD3_0_0_, xwikidocum0_.XWD_TITLE as XWD4_0_0_, xwikidocum0_.XWD_LANGUAGE as XWD5_0_0_, xwikidocum0_.XWD_DEFAULT_LANGUAGE as XWD6_0_0_, xwikidocum0_.XWD_TRANSLATION as XWD7_0_0_, xwikidocum0_.XWD_DATE as XWD8_0_0_, xwikidocum0_.XWD_CONTENT_UPDATE_DATE as XWD9_0_0_, xwikidocum0_.XWD_CREATION_DATE as XWD10_0_0_, xwikidocum0_.XWD_AUTHOR as XWD11_0_0_, xwikidocum0_.XWD_CONTENT_AUTHOR as XWD12_0_0_, xwikidocum0_.XWD_CREATOR as XWD13_0_0_, xwikidocum0_.XWD_WEB as XWD14_0_0_, xwikidocum0_.XWD_CONTENT as XWD15_0_0_, xwikidocum0_.XWD_VERSION as XWD16_0_0_, xwikidocum0_.XWD_CUSTOM_CLASS as XWD17_0_0_, xwikidocum0_.XWD_PARENT as XWD18_0_0_, xwikidocum0_.XWD_CLASS_XML as XWD19_0_0_, xwikidocum0_.XWD_ELEMENTS as XWD20_0_0_, xwikidocum0_.XWD_DEFAULT_TEMPLATE as XWD21_0_0_, xwikidocum0_.XWD_VALIDATION_SCRIPT as XWD22_0_0_, xwikidocum0_.XWD_COMMENT as XWD23_0_0_, xwikidocum0_.XWD_MINOREDIT as XWD24_0_0_, xwikidocum0_.XWD_SYNTAX_ID as XWD25_0_0_, xwikidocum0_.XWD_HIDDEN as XWD26_0_0_ from xwikidoc xwikidocum0_ where xwikidocum0_.XWD_ID=?], parameter 1 = [-4526159677276379501], schema = [TEST91]

Using Byteman

Byteman is a great framework that allows to modify bytecode in a running JVM. It can easily be used to add logging (for ex) to find out what's happening in a running XWiki instance. Here's a quick tutorial:

  • Download Byteman and unzip it in a directory. Set the $BYTEMAN_HOME environment property to point to the directory where you've unzipped it. For example:
    export BYTEMAN_HOME=/Users/vmassol/dev/byteman/byteman-download-2.1.0
  • Start an XWiki instance somewhere on the same machine
  • Go to $BYTEMAN_HOME/bin and connect Byteman to XWiki. For example:
    sh bminstall.sh -b -Dorg.jboss.byteman.transform.all jetty/start.jar
  • Now create a Byteman rule by creating a file, for example my.btm with the following:
    RULE XWiki Docs loaded
    CLASS XWikiHibernateStore
    METHOD loadXWikiDoc
    AT ENTRY
    IF TRUE
    DO traceln("Load document = " + $1.getDocumentReference())
    ENDRULE
  • Load this rule with: sh bmsubmit.sh -l my.btm
  • Call a URL in your wiki and check that the console prints the document references that get loaded! For example:
    Load document = xwiki:Main.WebPreferences
    Load document = xwiki:ColorThemes.DefaultColorTheme
    Load document = xwiki:XWiki.SearchSuggestConfig
    Load document = xwiki:XWiki.SearchSuggestConfig
    Load document = xwiki:Dashboard.WebHome
    Load document = xwiki:XWiki.GadgetClass
    Load document = xwiki:Dashboard.WebHome
    Load document = xwiki:Dashboard.WebPreferences
    Load document = xwiki:Dashboard.colibri
    Load document = xwiki:Main.Welcome
    ...
  • Modify your rule or add new rules to the same file and apply the changes with sh bmsubmit.sh -l my.btm
  • Remove your rules with sh bmsubmit.sh -u

For more read A Byteman tutorial or the Reference documentation.

Example

In this example we'll print calls to CommonsConfigurationSource.containsKey(...) with the parameters printed and the time it takes to execute. In addition we'll also print calls to XWiki.getDocument(String, XWikiContext) which is a deprecated method which, for the purpose of this example, we think generate the calls to containsKey.

RULE Create timer for containsKey
CLASS CommonsConfigurationSource
METHOD containsKey
AT ENTRY
IF TRUE
DO resetTimer("containsKey")
ENDRULE

RULE Calls to containsKey
CLASS CommonsConfigurationSource
METHOD containsKey
AT EXIT
IF TRUE
DO traceln("containsKey for [" + $1 + "] = [" + $! + "], time = [" + getElapsedTimeFromTimer("containsKey") + "]")
ENDRULE

RULE Calls to deprecated getDocument
CLASS com.xpn.xwiki.XWiki
METHOD getDocument(String, XWikiContext)
AT ENTRY
IF TRUE
DO traceStack("getDocument() called for [" + $1 + "] ", 3)
ENDRULE

Generates:

...
getDocument() called for [XWiki.Admin] com.xpn.xwiki.XWiki.getDocument(XWiki.java:-1)
com.xpn.xwiki.XWiki.getUserName(XWiki.java:5072)
com.xpn.xwiki.XWiki.getUserName(XWiki.java:5062)
  . . .
containsKey for [model.reference.default.document] = [false], time = [0]
containsKey for [model.reference.default.document] = [false], time = [0]
containsKey for [model.reference.default.space] = [false], time = [0]
containsKey for [model.reference.default.space] = [false], time = [0]
containsKey for [model.reference.default.wiki] = [false], time = [0]
containsKey for [model.reference.default.wiki] = [false], time = [1]
getDocument() called for [XWiki.DefaultSkin] com.xpn.xwiki.XWiki.getDocument(XWiki.java:-1)
com.xpn.xwiki.XWiki.getSkinFile(XWiki.java:1955)
com.xpn.xwiki.XWiki.getSkinFile(XWiki.java:1918)
  . . .
...

Debugging JavaScript

The solution is to use a Browser add-on for inspecting JavaScript and putting breakpoints in it. The issue is that by default the XWiki build will minify and aggregate JavaScript files for performance reasons.

However there's a solution:

  • Start by building XWiki with the debug profile (mvn clean install -Pdebug)
  • Then once you're on a page make sure to pass ?minify=false in the URL. If you don't do this then the aggregated JS files are going to be referenced and since they don't exist, the JS code will break

Debugging the WYSIWYG editor

Debugging the Java code

Debugging the client side Java code

Starting with GWT 2.0 we can run and debug the client side Java code directly in the browser. This is called Development Mode. Follow these steps:

  1. Copy src/test/resources/start_wysiwyg_noserver_debug.sh from the xwiki-gwt-wysiwyg-server module to the root of your XWiki Enterprise installation. For the standard jetty+hsqldb distribution this is the directory where start_xwiki.sh is located.
  2. chmod 755 start_wysiwyg_noserver_debug.sh
  3. Open start_wysiwyg_noserver_debug.sh with a text editor and make sure that the variables defined at the beginning of the file match what you have on your system.
  4. The GWT Development Mode requires GWT Java sources (so not only the byte code) to be in the class path. The debug script looks for the needed dependencies in the local maven repository. Building the xwiki-gwt-* modules ensures these dependencies are in your local maven repository. Alternatively you can edit the debug script and reference these dependencies with a different path.
  5. Start the server (e.g. ./start_xwiki.sh).
  6. ./start_wysiwyg_noserver_debug.sh
  7. Connect to the specified port using your IDE. The client side code is in the xwiki-gwt-wysiwyg-client maven module. Make sure you have imported it in your IDE.
  8. The GWT Development Mode window should have opened. Click "Copy to Clipboard" to copy the startup URL.
  9. Paste the startup URL in your browser's address bar and load it.
  10. You may be asked to login since you're going to edit a wiki page in WYSIWYG mode.
  11. You may be asked to install the GWT Developer plugin, if this is the first time you try to debug GWT code in Development Mode.
  12. If you receive a message that tells you your GWT code needs to be recompiled just refresh the page. Note that the exiting JavaScript code of the editor (resources/js/xwiki/wysiwyg/xwe) might be affected so you should backup it if you don't have other means of restoring it.
  13. At this point the WYSIWYG editor should be loaded and you should be able to add break points using your Java IDE. Currently the editor toolbar is badly displayed in debug mode due to some CSS issue we need to fix.

Debugging the server side code

You can debug the server side code remotely. Start your wiki in debug mode (e.g. using the start_xwiki_debug.sh script) and then connect with your IDE to the specified port. The server side code of the WYSIWYG editor is in the xwiki-gwt-wysiwyg-server module. Make sure you have imported it in your IDE.

Debugging the JavaScript code

The JavaScript code of the WYSIWYG editor is obfuscated by default to reduce its size. To be able to debug it you have to rebuild the editor using the detailed GWT compilation style. One way to achieve this is with the -Pdev maven profile. Alternatively you can edit the pom of the xwiki-gwt-wysiwyg-server module and change the value of the gwt.style property. After you rebuild the editor, update your XWiki Enterprise instance and clean your browser's cache. Note that with the detailed style the JavaScript code is huge (around 5MB currently) so most of the debuggers will respond pretty slow. Sometimes you can save time by adding your break points from the JavaScript code. Edit the <hash>.cache.html file that is loaded by your browser and add debugger where you want the execution to be stopped. A quick way to find methods in the detailed JavaScript code is to search for <ClassName>.prototype, e.g. RichTextArea.prototype.

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Created by VincentMassol on 2007/02/02 10:09

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