DFTracer Viewer (VS Code)
Open DFTracer traces (.pfw / .pfw.gz) in
an interactive timeline inside VS Code. The extension downloads a prebuilt
dftracer_server from
dftracer-utils, runs it on your trace
directory, and shows the timeline it serves - no separate install required.
Features
- Pan/zoom timeline with density level-of-detail re-query (stays fast on large traces).
- Lanes grouped by host or ordered flat by rank; flamegraph and caller/callee sandwich.
- Gap/idle analysis, I/O bandwidth strip, a full query box, and per-metric help tooltips.
- Works over Remote-SSH / Codespaces / devcontainers (the server runs on the remote host).
Usage
- Double-click a
.pfw / .pfw.gz file, or
- Right-click a trace file -> DFTracer: View Trace, or a folder -> DFTracer: View Traces, or
- Run DFTracer: View Trace / DFTracer: View Traces from the command palette.
On first use the extension downloads the dftracer_server binary for your
platform from
dftracer-utils-prebuilds
and caches it. Prebuilts are available for macOS and Linux (x64 / arm64).
Choosing the server
Run DFTracer: Select Server from the command palette to pick where the
server comes from - download the prebuilt one, browse for a dftracer_server
binary, or type a path - much like selecting a Python interpreter. The viewer's
start screen has the same "use your own build" field, and the choice is stored
in dftracer.viewer.serverPath.
To fetch a newer prebuilt later, run DFTracer: Update Server; it re-downloads
the selected release and reloads the open viewer.
Settings
| Setting |
Default |
Purpose |
dftracer.viewer.serverPath |
(empty) |
Path to a dftracer_server binary; when set, skips the download. |
dftracer.viewer.serverRelease |
latest |
Which prebuilds release to download (latest or a tag like v1.2.3.post5). |
dftracer.viewer.indexDir |
(empty) |
Trace index directory (--index-dir). Empty builds it in a temp dir removed on close; set to persist. |
dftracer.viewer.extraArgs |
[] |
Extra CLI args passed to dftracer_server. |
How it works
Each opened trace directory gets one dftracer_server process on a free
localhost port, mapped through vscode.env.asExternalUri (so it works in
Remote-SSH / Codespaces / devcontainers). The webview loads the UI the server
serves at GET /; servers are reference-counted and stopped when their last
viewer tab closes. Opening traces from different folders runs independent
servers; opening several files from one folder shares a server, each tab scoped
to its file. Unless indexDir is set, the index lives in a temporary directory
that is removed when the server stops.
Develop
npm install
npm run compile # or: npm run watch
npm test # headless VS Code tests
Press F5 in VS Code to launch an Extension Development Host (it generates sample
traces under fixtures/ and opens them).
