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We can now click right and drag to zoom in xy-charts

 Contributes towards fixing #389

Signed-off-by: Ibrahim Fradj <>

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Trace Viewer extension for Theia applications

Theia trace viewer extension using the tsp-typescript-client ( and Trace Server Protocol (

Prerequisites for running this extension are the same as those for running the theia IDE.

👋 Want to help? See how to contribute code.

Try a live demo via Gitpod!

Click the Gitpod button below to access a live demo of the trace viewer. In a couple clicks and around 2 minutes you'll be on your way.

Gitpod ready-to-code

Prerequisites: A GitHub account (for logging into Gitpod)

  • Click here to open Gitpod.
  • After logging in, it takes around a minute for Gitpod to set up the in-browser IDE used to build the project.
  • When the workspace has loaded, the project builds automatically in about a minute. Then, the workspace pops a notification saying a service (i.e. the tool) is now available. gitpod-service-ready-notification
  • After opening the tool via the notification, the interface loads in a few seconds.
  • Now you're ready to try the trace viewer!
    • Head to the trace viewer tab in the left side menu to get started.
    • The tool is already loaded with example traces from a set of Trace Visualisation Labs, so no need to hunt for your own.


Consume the trace viewer extension from npm

We plan to distribute this extension on npm.

Availability: TBD

Build the extension and example application

Here is the step in order to build the trace viewer

  1. Clone this theia-trace-extension repository
  2. cd theia-trace-extension
  3. Now you are ready to build the application: yarn

Note for some debian-based machines: On some distros, there are 2 yarn commands. If you get an error message saying ERROR: There are no scenarios; must have at least one., you are using the wrong yarn. See

You can also run two scripts to watch for changes and rebuild automatically:

  1. From the root:
yarn tswatch # to compile TypeScript files
  1. In parallel run:
cd examples/<browser or electron>
yarn watch # to update the frontend bundles (loaded by the browser)

Try the trace extension

This repository contains an example trace-viewer application that includes the trace extension. It has two versions:

  • browser: a "browser" application, accessed with a web browser
  • electron: a native desktop application

You can find those example applications under examples/.

Run the Trace Server

In order to open traces you need a trace server running on the same machine as the trace extension. You can download the Eclipse Trace Compass server or let yarn download and run it:

  $ yarn download:server
  $ yarn start:server

You can also build the trace-server yourself using Trace Compass and the Incubator, take a look at the instructions here.

Run the example app

From the repo root, run either

  $ yarn start:browser

And go to http://localhost:3000.


  $ yarn start:electron

And use the Electron application.

Change the trace server URL

By default, the trace server is expected to be on responding at http://localhost:8080/tsp/api. If it is not the case, the URL can be changed using the TRACE_SERVER_URL environment variable when running the app.

For example, to start the browser example app with a specific URL, one can run

 $ TRACE_SERVER_URL=https://my.trace.server:port/tsp/api yarn start:browser

Package the Example Theia Trace Viewer Application

It's possible to package the repo's example application with electron-builder. After running yarn in the repo root, do:

  $ cd electron-app
  $ yarn package

The configured Linux packaging(s) will be generated folder electron-app/dist

Using the trace extension

This section describes how to operate the Theia trace extension to view and analyze traces. The UI, view interactions, and UX are prelimiary and subject to revisions in the future.


Open a trace

To open a trace in the Theia Trace Extension, use the File Explorer in Theia to navigate to the trace directory. Then right-mouse click on the trace and select menu Open With->Open Trace.

Open Trace

If the selection is a single file, then the tool will open the file directly as a trace.

If the selection is a directory, then the tool will look for traces in Common Trace Format (CTF) format, such as Linux Tracing Toolkit traces (LTTng) Kernel and UST (Userspace) traces, and open all found CTF traces together under the same timeline. The trace events of each CTF trace will be analyzed in chronological order. With this you're able to open e.g. LTTng Kernel and UST Traces at the same time.

The example Trace Compass trace server above supports LTTng Kernel and UST traces. Example LTTng traces can be retrieved from the Trace Compass Tutorials. Just download the archive TraceCompassTutorialTraces, extract them into a local directory on your computer. They can also be automatically downloaded by running yarn download:sample-traces from the repository's root.

Open the Trace Viewer

To open the Trace Viewer, select menu View from the top-level menu and then select Trace Viewer in the list of views. Then the Trace Viewer icon will be added on the left navbar, below the File Explorer Icon.

Select the Trace Viewer icon to switch to the trace viewer.

Trace Viewer

Now, you will see 3 sections: Opened Traces, Available Views and Time Graph Tooltip. Select the trace that you opened and the available views will be populated. Now you can select different views and they will be added into a single container view for that trace.

Navigation and zooming

There is only a limited number of such operations and they are only implemented in the Time Graph views (the ones looking like Gantt charts). For Zoom-in/out use CTRL+mouse wheel. Or use left mouse drag on time axis on top. Navigating the trace you can use the scrollbar at the bottom of the trace timeline container.

Time Graph Tooltip

Currently, the Time Graph Tooltip is populated when selecting a state in a Time Graph view.

How to contribute code

Changes to the project are made by submitting code with a pull request (PR).

Good commit messages make it easier to review code and understand why the changes were made. Please include a:

  • Title: Concise and complete title written in imperative (e.g. "Update Gitpod demo screenshots" or "Single-click to select or open trace")
  • Problem: What is the situation that needs to be resolved? Why does the problem need fixing? Link to related issues (e.g. "Fixes #317").
  • Solution: What changes were made to resolve the situation? Why are these changes the right fix?
  • Impact: What impact do these changes have? (e.g. Numbers to show a performance improvement, screenshots or a video for a UI change)
  • Sign-off: Use your full name and a long-term email address. This certifies that you have written the code and that, from a licensing perspective, the code is appropriate for use in open-source.
  • How to format the message