runtime/pprof: Documentation of SetCPUProfileRate

[tpudlik]

The docstring for SetCPUProfileRate states,

Most clients should use the runtime/pprof package or the testing package's -test.cpuprofile flag instead of calling SetCPUProfileRate directly.

However, the -test.cpuprofile flag does not allow you to set the CPU profile rate, only the name of the file to which the profile should be written out to. The sentence quoted above should probably be removed.

[ianlancetaylor]

The docs are correct. Although the testing package's -test.cpuprofile flag is not a complete replacement for runtime.SetCPUProfileRate, it does essentially call the function with a fixed value, namely 100. So we are recommending that people use -test.cpuprofile rather than write their code to call runtime.SetCPUProfileRate.

Note that the same is true of the runtime/pprof package that is also mentioned: it calls runtime.SetCPUProfileRate, but always passes either 100 or 0.

Closing because there is nothing to do.