HowToDebug

How to Debug

(For tutorial on how to use ChromeDevTools Debugger to debug JavaScript see the dedicated page. This page is about debugging Debugger itself.)

Since the project is written in Java, it must be relatively easy to debug it from a Java IDE.

You may want to look inside the running code if you are wondering how it works or if you see a problem and wish to contribute to the project by investigating.

See also HowToBuild, HowToReportProblem.

Debugging EclipseDebugger

Our Debugger is an Eclipse plugin (technically a set of plugins), so you have to start the entire Eclipse (here called debuggee) under a Java debugger. Fortunately Eclipse framework is quite prepared for this. What you need is just another Eclipse instance (here called debugger) with installed Plugin Development Environment feature (Eclipse Classic has it preinstalled).

Debuggee must have usual Chromium JavaScript Remote Debugger feature plus ChromeDevTools Project Source Code feature (one prepared specifically for such occasions). (We assume you are installing debugger, not building it from sources, otherwise you don't need such instructions.)

Start debugger. First, some steps to prepare it:

1. In Preferences under Plug-in Development set up new Target Platform: press Add, Start with empty, Add Installation and enter a path to your debuggee installation directory. To double-check, it should find some plugins while in the same dialog window.
2. Open Plug-in Development perspective. On the left choose Plug-ins tab. In the tab choose all org.chromium.* plugins (or better all plugins) and from context menu make Add To Java Search on them.
3. Go to Java perspective. In Package Explorer tab in triangle menu choose Filters and deselect External plug-ins project.
4. Open Debug Configurations dialog and create new Eclipse Application launch debug configuration.
5. It's ready to start now.

All the classes should be under External Plug-in Libraries/External Plug-ins in Package Explorer. They are also available from the regular Open Type (Ctrl+Shift+T) dialog window.

Where to Start Debugging

Finding a place for the first breakpoint in an unfamiliar codebase may be tricky. If you have a stacktrace (HowToReportProblem tells how to fetch one from an error message), everything should be quite straightforward. In other cases, there is probably no general instruction. We welcome you to ask in discussion group if clueless.