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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I answered this with strace, obviously — I straced go tool pprof and this is what I saw:. For help, type pproof. Its execution time is similar to the Go program’s:. Index responds with the pprof-formatted profile named by the request. The profiler requires a final call to StopCPUProfile to flush any pending writes to the file before the program exits; we use defer to make sure this happens as main returns.

The stylistic changes have only a minor effect on the run time: Excluding the recursion, it looks like the time is going into the accesses to the number map on lines, and Or to look at the holders of contended mutexes, after calling runtime.

The Go Programming Language. StartCPUProfile returns an error prpof profiling is already enabled. We can also generate a PNG profile like this: The first two columns show the number of samples in which the function was running as prpof to waiting for a called function to returnas a raw count and as a percentage of total samples. The web command writes a graph of the profile data in SVG format and opens it in a web browser. There is also a gv command that writes PostScript pprog opens it in Ghostview.


Profiling Go programs with pprof

The first three columns are the number of samples taken while running that line, the number of samples taken while running that line or in code called from that line, and the line number in the file.

Fatal “could not create CPU profile: Every time FindLoops is called, it allocates some sizable bookkeeping structures. To view all available profiles, open http: In addition to these performance changes, the final version is written using idiomatic Go lprof, using data structures and methods.

Fatal “could not write memory profile: There are many commands available from the pprof command line. For example in a heap profile, the stack trace has a number of bytes of memory attached to it.

FindLoops is allocating about Package pprof serves via its HTTP server runtime profiling data in the format expected by the pprof visualization tool. There’s no reason to use a map when an array or slice will do. It’s hard to tell what’s going on in pprof graph, because there are many nodes with small sample numbers obscuring the big ones.

In the call graph viewer below, each node is a function belonging to this package and its children are the functions it calls—perhaps dynamically. Context, labels LabelSet, f func context. To use pprof, link this package into your program: Profiling a Go program The first step to profiling a Go program is to enable profiling.


Terms of Service Privacy Policy. That’s 11 times faster than the program we started with.

Profiling Go Programs – The Go Blog

Add panics if the profile already contains a stack for value. Instead of using a map, we can use a simple slice to list ho elements. Except as notedthe content of this page is licensed under the Creative Commons Attribution 3. DFS function was more than frames deeper than main. It looks like the current bottleneck is the same as the last one: Label returns the value of the label with the given key on ctx, and a boolean indicating whether that label exists.

A sample is a stack trace, and this stack trace has 2 locations: 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. Otherwise, WriteTo returns nil. In this case, a simple solution is fo introduce a cache so that each call to FindLoops reuses the previous call’s storage when possible.