Documentation

Profiler.

One CPU and memory profiler for every language server.

An orange shared engine connects to two terminal surfaces through circuit paths.

lsp-profiler profiles a running language server without leaving the editor. A language plugs in a runtime crate; sessions, reports and the protocol are shared.

SharpLsp · C# and F# language server for VS Code ↗Unedited, in real time: Profile CPU on a running process, then the results open. Watch the walkthrough ↗

What it measures

  • CPU: sampling sessions, hotspots and flame graphs, exported as speedscope or V8 profiles.
  • Memory: heap snapshots, retention paths and leak scoring.
CheckoutPipeline.cs with inline heat bars: ParseCatalog 66.8 percent, PriceBasket 25.1 percent, RenderInvoice 7.6 percent
SharpLsp · C# and F# language server for VS Code ↗Hot lines, painted in the source.
SharpLsp Profiler results panel with summary cards, an embedded flame graph and the hot functions table
SharpLsp · C# and F# language server for VS Code ↗Results panel, flame graph and hot functions.
Memory dashboard with a steadily climbing heap timeline flagged as a possible leak, beside SessionCache.cs
SharpLsp · C# and F# language server for VS Code ↗Live heap timeline.
Suspected leaks ranked HIGH with growth in megabytes and object counts, and an inline leak marker on the CustomerSession declaration
SharpLsp · C# and F# language server for VS Code ↗Ranked leak suspects, marked in the source.
Flame graph zoomed into ParseCatalog, showing the System.Text.Json deserialization stack
SharpLsp · C# and F# language server for VS Code ↗Zoom the flame graph into one call.
SharpLsp · C# and F# language server for VS Code ↗Memory tracking, sped up three times: the heap timeline climbs and leak suspects appear. Watch the walkthrough ↗

How it fits together

  1. Your server mounts lsp-profiler and a runtime crate, such as lsp-profiler-dotnet for .NET.
  2. The editor talks to it over one JSON-RPC protocol.
  3. @nimblesite/lsp-profiler-ui renders the results in VS Code.
busy.osp in VS Code with inline heat bars: collatz 76.4 percent, longest 73.0 percent, fib 22.5 percent
Osprey · native functional language with a VS Code extension ↗Heat on Osprey source.
Osprey Profiler panel: 812 samples over 8 seconds, 5 functions, 6 hot lines, above a left-heavy flame graph
Osprey · native functional language with a VS Code extension ↗Osprey results panel and flame graph.

Add it

cargo add lsp-profiler
cargo add lsp-profiler-dotnet   # for .NET language servers

See it running in SharpLsp and Osprey. The full design is in the profiler spec.