The developer docs: ; The output of go tool pprof –help (I pasted the output on my. Step #5: run go tool pprof. Pass your binary location, and the location of the cpu. pprof file as returned when running your program. You can. To build and install it, use the go get tool. go get -u Remember to set GOPATH to the directory where you want pprof to be installed.

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The web command writes topl graph of the profile data in SVG format and opens it in a web browser. Package pprof writes runtime profiling data in the format expected by the pprof visualization tool.

SetMutexProfileFraction in your program: The program sources, Linux x binaries, and profiles used to write this post are available in the benchgraffiti project on GitHub. If we look at pprif pprof protobuf definitionyou see that a profile is mostly a bunch of Sample s.

WriteHeapProfile is shorthand for Lookup “heap”.

Each box in the graph corresponds to a single function, and the boxes are sized according to the number of samples in which the function was running. Or to look at the goroutine blocking profile, after calling runtime.

By using Go’s profiling tools to identify and correct specific bottlenecks, we can make the Go loop finding program run an order of magnitude faster and use 6x less memory. In an HTTP server, adding. Symbol looks up the program counters listed in the request, responding with a table mapping program counters to function names.

The new code defines a flag named cpuprofilecalls the Go flag library to parse the command line flags, and then, if the cpuprofile flag has been set on the command line, starts CPU profiling redirected to that file. To view all available profiles, open http: While profiling, the profile will be buffered and written to w. The third column shows the running total during the listing: Profiles can then be visualized with the pprof tool: In addition to writing that function, changing the Go program to use slices instead of maps requires changing just a few lines of code.


In particular this post on custom pprof profile types and this on the newish profile type for seeing contended mutexes are great. It was generating these heap profiles named like pprof. The augmented label map will be set for the duration of the call to f and restored once f returns. The first step to profiling a Go program is to enable profiling. We will not be using Java or Scala, because we are not skilled at writing efficient programs in either of those languages, so the comparison would be unfair.

Request func Symbol w http. For example, the following command runs benchmarks in the current directory and writes the CPU and memory profiles to cpu. Now the samples we are examining are memory allocations, not clock ticks. So I decided to write a program that allocates a bunch of memory to profile with pprof. A Profile is a collection of stack traces showing the call sequences that led to instances of a particular event, such as allocation.

pprof – The Go Programming Language

StopCPUProfile only returns after all the writes for the profile have completed. To add equivalent profiling support to a standalone program, add code like the following to your main function: A label to a prior label with the same key. Profiles are only as good as the kernel support used to generate them. There is also a gv command that writes PostScript and opens it in Ghostview.


That’s reasonable when a map is being used to hold key-value pairs, but not when a map is being used as a stand-in for a simple set, as it is here. We can also generate a PNG profile like this: To analyze these profiles lists of stack tracesthe tool to use is go tool pprofwhich is a bunch of tools for visualizing stack traces.

The normal way to use pprof seems to be: For more information about pprof, see https: WithLabels returns a new context. So the function to blame for the memory leak might be totally different than the function listed in the heap profile.

Profiling Go programs with pprof

This exception helps mainly in programs running without garbage collection enabled, usually for debugging purposes. Do calls f with a copy of the parent context with the gi labels added to the parent’s label map. The stack trace samples contain more interesting data about function call relationships than the text listings can show.

Now memory allocation and the consequent garbage collection runtime.

Profiling Go programs with pprof – Julia Evans

Benchmarks are only as good as the programs they measure. For help, type ‘help’. The normal way to use pprof seems to be:. Handler func Index w http. It is a no-op if the value is not in the profile.

See the diff between havlak1 and havlak2.

How can I make this choice after the fact?