JvmScope — Java Thread Dumps & TLS Logs for VS Code

Investigate Java thread dumps and Java TLS/SSL logs (JSSE) inside VS Code, using the same analysis engines as JvmScope's browser application. No Java installation, server, account or external analysis service is needed.

This is the 0.3 native sidebar preview. The two analyzers are bundled webviews with native file opening, clipboard, read-only raw evidence and export dialogs. The package also contains the searchable help, examples and knowledge base.

Install

In VS Code, open Extensions and search for RobbanHoglund.jvmscope. Install the extension, then run JvmScope: Open Analysis Sidebar from the Command Palette. The release is labeled Preview while broader desktop feedback is collected.

For an unpublished build or offline installation:

1. Download the jvmscope-vscode artifact from the branch's VS Code extension checks workflow and unzip it.
2. In VS Code, run Extensions: Install from VSIX… and select jvmscope-0.3.2.vsix.
3. Open the Command Palette and run JvmScope: Open Java Thread Dump Analyzer or JvmScope: Open Java TLS Log Analyzer.

Alternatively, build the package using the instructions below. Requires VS Code 1.110 or later on desktop. Browser-hosted VS Code (vscode.dev) is not included in this first version.

Analyze captures

• Right-click a capture in Explorer and choose 🧵 Analyze as Java Thread Dump or 🔒 Analyze as Java TLS Log.
• Select several thread dump files to compare snapshots. TLS analysis opens one log at a time.
• Run either Analyze as… command from the Command Palette to analyze the active editor, including unsaved changes and untitled documents.
• Inside an analyzer, use Choose dumps / Choose log to open the native file picker, or try the bundled examples.
• Raw dump opens exact snapshot text in a read-only VS Code editor. Copy controls use the VS Code clipboard. Findings and graph exports use a Save dialog.

Imports are UTF-8 text/JSON, limited to 64 MiB total per import and 50 files. The limits bound file transfer, not analysis complexity. Choose smaller captures if memory use becomes excessive. Inputs are analyzed on demand: later edits to a file do not silently change the current analysis. A new Analyze as… command replaces that analyzer's input; TDA's in-view Add/Replace control still applies to its file picker and Paste actions.

Browse analyses in the sidebar

Open JvmScope in the Activity Bar, or run JvmScope: Open Analysis Sidebar. The two roots open the Java thread dump and Java TLS analyzers. The view's toolbar also opens either analyzer.

• Java thread dumps: expand a source file, then a snapshot, then its threads. Select a thread to open its details in the correct snapshot, even when names repeat.
• Java TLS logs: expand the file, an interaction, then its observed events. Select an event to show and highlight it in the investigation sequence. This switches to investigation mode and clears table filters if they hide that interaction.
• Long branches show 100 items at a time; expand More (…) for the next page. The sidebar shows the whole loaded analysis, independently of table filters.
• Clear, replace or close an analyzer to update its tree. An invalid TDA replacement preserves the existing analysis. Old items cannot select objects in a new capture.

The tree uses the same uncertainty qualifications as the analyzers. In particular, ambiguous legacy TLS grouping does not produce a single-connection event sequence. Items represent captured observations; they are not live JVM threads or connections. The sidebar also works with bundled examples and pasted captures.

Navigate to source

Thread details offer Open source in VS Code. In TLS, use Open source, a sequence event line number, or a raw-log line number. These open the original capture beside the analysis and select the evidence lines, including the correct snapshot in files containing multiple dumps. This navigates the capture, not Java application source code.

Links are available for files and editor documents imported through VS Code. Examples and pasted captures have no original-document link. If the document contents change, navigation asks you to analyze it again before selecting lines. Clearing/replacing the input or closing the panel revokes its source links.

Privacy and scope

Captures stay in the VS Code extension host and its webviews. There is no upload, telemetry, background workspace scan or JVM process execution. A remote workspace can read a selected capture through VS Code's filesystem API; its contents must then be transferred to the UI to display and analyze it. Documentation links open in your browser only when clicked.

Sessions are held in memory, survive switching editor tabs, and disappear when the analyzer panel is closed or VS Code reloads. Raw evidence is invalidated when its owning capture is cleared/replaced or its panel closes. Exports can contain sensitive diagnostic data; review them before saving or sharing.

Both views follow VS Code light, dark and high-contrast themes and adapt to narrow editor splits. The standalone application and exported reports retain their own palettes. Raw snapshots still open in the native read-only editor. The verified inputs are HotSpot thread dumps and SunJSSE traces; missing fields remain unknown. This extension adds no additional JVM/vendor compatibility claim.

Develop and test

From the repository root, with Node.js 24:

npm ci --prefix frontend
npm ci --prefix extensions/vscode
npm run build --prefix extensions/vscode
npm test --prefix extensions/vscode
npx --prefix frontend playwright install chromium
npx --prefix frontend playwright test --config extensions/vscode/test/playwright.config.mjs
npm run test:integration --prefix extensions/vscode
npm run package --prefix extensions/vscode

On headless Linux, wrap the extension-host command in xvfb-run -a. The integration runner downloads the pinned minimum VS Code version into an isolated test directory. CI installs the same packaged VSIX on Linux, Windows and macOS, and also tests the current stable VS Code on Linux. To test a package locally, set VSCODE_VSIX=build/vscode/jvmscope-0.3.2.vsix before running test:integration (path relative to the repository root). Python 3 can also check the archive and rewritten Marketplace links with python3 extensions/vscode/test/package.py. Set VSCODE_VERSION to test another release, or VSCODE_EXECUTABLE to use an existing test installation. It never uses your normal VS Code profile or installed extensions.

For interactive development after building:

code --extensionDevelopmentPath="$PWD/extensions/vscode"

The .vsix is written under build/vscode/. Generated webview assets are excluded from git and rebuilt from the shared frontend. The package has no production npm dependencies. No Marketplace publication is performed by these commands or CI. The manifest's publisher identifier must be verified against the actual publisher account before a public release.

Next stage

Further work can add carefully scoped Problems diagnostics, opt-in refresh after edits, and session serialization with clear privacy choices. These features should use the same parsers and rule models; a dump observation must never become a stronger claim merely because it appears in VS Code. See the implementation plan.