Profile the code

Identify the 3% critical code that needs to be optimized.

97% of the time: premature optimization is the root of all evil.

A CPU profile

A CPU profile identifies the functions whos execution requires the most CPU time.

go test -cpuprofile=cpu.out

A heap profile

A heap profile identifies the statements responsible for allocating the most memory.

go test -memprofile=mem.out

A blocking profile

A blocking profile identifies the operations responsible for blocking goroutines the longest, such as system calls, channel sends and receives, and acquisitions of locks.

go test -blockprofile=block.out

Runtime profile

Go runtime’s profiling features can be enabled under programmer control using the runtime API.

Analize profile with pprof tool

Once we’ve gathered a profile, we need to analyze it using the pprof tool.

go tool pprof

Summary

// the benchmark test are disabled with NONE
go test -run=NONE -bench=ClientServerParallelTLS64 -cpuprofile=cpu.log net/http

go tool pprof -text -nodecount=10 ./http.test cpu.log

Example

the path to the package to profile is src/tests/word