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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NewProfile creates a new profile with the given name. StopCPUProfile only returns after all the writes for the profile have completed.

Profiling Go programs with pprof – Julia Evans

Each Profile has a unique name. Cmdline responds with the running program’s command line, with arguments separated by NUL bytes. In all but one of the cases where maps are being used, it is impossible for the algorithm to insert a duplicate element. The programs are run on a computer with a 3.

Context func ForLabels ctx context. The profile has samples, so it was running for a bit over 25 seconds. The normal way to use pprof seems to be:. If there has been no garbage collection at all, ppdof heap profile reports all known allocations.

So the stack traces in the heap profile might be for code that is not running anymore — like toool a function allocated a bunch of memory, returned, and a different function that should be freeing that memory is misbehaving.


The new code defines a flag named cpuprofilecalls the Go flag library to parse the command line flags, and og, if the cpuprofile flag has been set on the command line, starts CPU profiling redirected to that file.

Package pprof writes runtime profiling data in the format expected by the pprof visualization tool. Packages can create and maintain their own profiles; the most common use is for tracking resources that must be explicitly closed, such as files or network connections. Changing number from a map to a slice requires pptof seven lines in the program and cut its run time by nearly a factor of two:.

We can follow the thick arrows easily now, to see that FindLoops is triggering most of the garbage collection. A small fragment of the full graph looks like:.

If a write to w returns an error, WriteTo returns that error. So you get a history of both allocations and frees for some sample of memory activity. Except as notedfool content of this page is licensed under the Creative Commons Attribution 3.

Profiling Go Programs – The Go Blog

For that particular lookup, a map is not the most efficient choice. Context, labels LabelSet, f func context. So I decided to write a program that allocates a bunch of memory to profile with pprof. We’ll time the program using Linux’s time utility with a format that shows user time, system time, real time, and maximum memory usage:.


I think the Samples are the most important part of the profile.

Context, f func og, value string bool func Label ctx context. For more information about pprof, see https: How did you do that, go tool pprof?! Profile responds with the pprof-formatted cpu profile.

Profiling Go programs with pprof

For example here are the comments about setting the sample rate:. I think how the heap profiles work is — allocations are recorded at some sample rate. Fatal “could not create memory profile: Add 1 go leakyFunction wg wg. FindLoops is allocating about The web command writes a graph of the profile data in SVG format and opens it pprov a web browser. FindLoops function was running in String “memprofile”, “”, “write memory profile to this tpol I answered this with strace, obviously — I straced go tool pprof and this is what I saw:.

Now memory allocation and the consequent garbage collection runtime.

A sample is a stack trace, and this stack trace has 2 locations: To find out why the garbage collector is running so much, we have to find out what is allocating memory. You can download a gunzipped version profile. This contains 1 sample. The stack trace samples contain more interesting data yo function call relationships than the text listings can show.