fgprof is a sampling Go profiler that allows you to analyze On-CPU as well as [Off-CPU](http://www.brendangregg.com/offcpuanalysis.html) (e.g. I/O) time together.
Handler returns an http handler that takes an optional "seconds" query argument that defaults to "30" and produces a profile over this duration. The optional "format" parameter controls if the output is written in Google's "pprof" format (default) or Brendan Gregg's "folded" stack format.
Start begins profiling the goroutines of the program and returns a function that needs to be invoked by the caller to stop the profiling and write the results to w using the given format.
const ( // FormatFolded is used by Brendan Gregg's FlameGraph utility, see // https://github.com/brendangregg/FlameGraph#2-fold-stacks. FormatFolded Format = "folded" // FormatPprof is used by Google's pprof utility, see // https://github.com/google/pprof/blob/master/proto/README.md. FormatPprof Format = "pprof" )