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Profiling

Timecraft can generate CPU and memory profiles from a historical trace of execution.

Timecraft uses wzprof to profile applications compiled to WebAssembly. For a deep dive into the technology, see this blog post.

Generating Profiles​

Here's an example process:

$ timecraft run testdata/go/echo.wasm foo
9341c1c8-1d9b-43b5-a140-b36f866e00cf
foo

To generate profiles, use the timecraft profile command. This will generate a CPU profile and memory profile, and write them to the registry:

$ timecraft profile 9341c1c8-1d9b-43b5-a140-b36f866e00cf
PROFILE ID    PROCESS ID                            TYPE    START   DURATION  SIZE
a53837e395c3  9341c1c8-1d9b-43b5-a140-b36f866e00cf  cpu     6s ago  5ms       37.6 KiB
219b8e22df5a  9341c1c8-1d9b-43b5-a140-b36f866e00cf  memory  6s ago  5ms       2.17 KiB

The timecraft profile command has options to control things like the time range and sampling rate. See timecraft profile -h.

Viewing Profiles​

To export a profile from the registry, use timecraft export profile:

timecraft export profile a53837e395c3 profile.out

To view the profile interactively, use:

go tool pprof -http :3000 profile.out

Profiling Issues​

dot executable not found in path​

Try brew install graphviz or sudo apt install graphviz