Debugging

This guide demonstrates various tools for inspecting and investigating possible performance issues within your Wails app using

• runtime/trace to create performance graphs and inspect them in a browser

Creating performance traces

1. Prepare your app for Tracing

   Close to your program entrypoint, ensure code along the following lines exists

   // Create the file to store our trace data within
   traceFile, err := os.Create("trace.out")
   if err != nil {
     log.Fatalf("trace.out could not be created: %v", err)
   }
   
   // Start the trace
   if err := trace.Start(traceFile); err != nil {
     _ = traceFile.Close()
     log.Fatalf("trace.start could not start: %v", err)
   }
   
   // Trace cleanup on exit. Alternatively,
   defer func() {
     trace.Stop()
     _ = traceFile.Close()
   }()
   
   ...Start your wails app here...

   Output will be saved to trace.out within your working path with metrics covering the complete runtime of your app. The default trace is quite raw; you are well advised to do further reading on trace to add more contextual information and limit what you actually record. For example: WithRegion, NewTask, Log

2. Run your app to create the trace

   With your app running, a continuous trace will be produced up to the point of exit so go ahead and perform some actions in your app and exit when complete

3. Install Visualisation helpers

   Some views need Graphviz. You can verify it is installed by running dot -V

   # macOS
   brew install graphviz
   
   # Ubuntu/Debian
   sudo apt-get install graphviz
   
   # Arch
   sudo pacman -S graphviz

4. Visualize your trace

   With your trace data available, we can start up the web interface

   go tool trace trace.out

   This should open up your default browser (recommended to use Chrome-based) with the trace event viewer home page.

   For first-time users, the Syscall profile screen is probably the most useful. This provides a breakdown of exactly what the program is doing along with timings