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Better pprof decoding tutorial

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Felix Geisendörfer
2021-04-14 09:12:36 +02:00
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pprof.md
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@ -32,11 +32,27 @@ The code for generating pprof output in Go can be found in: [runtime/pprof/proto
### Decoding
Below are a few tools for decoding pprof files into human readable text output. They are ordered by the complexity of their output format, with tools showing simplified output being listed first:
#### Using `pprofutils`
[pprofutils](https://github.com/felixge/pprofutils) is a small tool I build for converting between pprof files and Brendan Gregg's [folded text](https://github.com/brendangregg/FlameGraph#2-fold-stacks) format. You can use it like this:
```
$ pprof2text < examples/cpu/pprof.samples.cpu.001.pb.gz
golang.org/x/sync/errgroup.(*Group).Go.func1;main.run.func2;main.computeSum 19
golang.org/x/sync/errgroup.(*Group).Go.func1;main.run.func2;main.computeSum;runtime.asyncPreempt 5
runtime.mcall;runtime.gopreempt_m;runtime.goschedImpl;runtime.schedule;runtime.findrunnable;runtime.stopm;runtime.notesleep;runtime.semasleep;runtime.pthread_cond_wait 1
runtime.mcall;runtime.park_m;runtime.schedule;runtime.findrunnable;runtime.checkTimers;runtime.nanotime;runtime.nanotime1 1
runtime.mcall;runtime.park_m;runtime.schedule;runtime.findrunnable;runtime.stopm;runtime.notesleep;runtime.semasleep;runtime.pthread_cond_wait 2
runtime.mcall;runtime.park_m;runtime.resetForSleep;runtime.resettimer;runtime.modtimer;runtime.wakeNetPoller;runtime.netpollBreak;runtime.write;runtime.write1 7
runtime.mstart;runtime.mstart1;runtime.sysmon;runtime.usleep 3
```
#### Using `go tool pprof`
The easiest way to decode a pprof file and see its contents is to use `go tool pprof -raw`. The output is formatted for human readability, so arguabiliy it's not as `-raw` as the `protoc` output shown later on.
Let's have a look at the [examples/cpu/pprof.samples.cpu.001.pb.gz](./examples/cpu/pprof.samples.cpu.001.pb.gz) CPU profile included in this repository:
`pprof` itself has an output mode called `-raw` that will show you the contents of a pprof file. However, it should be noted that this is not as `-raw` as it gets, checkout `protoc` below for that:
```
$ go tool pprof -raw examples/cpu/pprof.samples.cpu.001.pb.gz