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guide: improve block profiler examples

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Felix Geisendörfer
2022-01-19 09:06:57 +01:00
parent f5f05409e8
commit be329ecc6c
1 changed files with 10 additions and 4 deletions
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guide/README.md
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@ -349,7 +349,13 @@ There are a few known issues and limitations of the memory profiler that you mig
## Block Profiler
The block profiler in Go measures how much time your goroutines spend Off-CPU while waiting for channel operations as well as mutex operations provided by the [sync](https://pkg.go.dev/sync) package.
The block profiler in Go measures how much time your goroutines spend Off-CPU while waiting for channel as well as mutex operations provided by the [sync](https://pkg.go.dev/sync) package. The following Go operations are hooked up to the block profiler:
- [select](https://github.com/golang/go/blob/go1.15.7/src/runtime/select.go#L511)
- [chan send](https://github.com/golang/go/blob/go1.15.7/src/runtime/chan.go#L279)
- [chan receive](https://github.com/golang/go/blob/go1.15.7/src/runtime/chan.go#L586)
- [semacquire](https://github.com/golang/go/blob/go1.15.7/src/runtime/sema.go#L150) ( [`Mutex.Lock`](https://golang.org/pkg/sync/#Mutex.Lock), [`RWMutex.RLock`](https://golang.org/pkg/sync/#RWMutex.RLock) , [`RWMutex.Lock`](https://golang.org/pkg/sync/#RWMutex.Lock), [`WaitGroup.Wait`](https://golang.org/pkg/sync/#WaitGroup.Wait))
- [notifyListWait](https://github.com/golang/go/blob/go1.15.7/src/runtime/sema.go#L515) ( [`Cond.Wait`](https://golang.org/pkg/sync/#Cond.Wait))
⚠️ Block profiles do not include time spend waiting on I/O, Sleep, GC and various other waiting states. Additionally blocking events are not recorded until they have completed, so the block profile can't be used to debug why a Go program is currently hanging. The latter can be determined using the Goroutine Profiler.
@ -373,9 +379,9 @@ Regardless of how you activate the block profiler, the resulting profile will es
|stack trace|contentions/count|delay/nanoseconds|
|-|-|-|
|main;foo|5|867549417|
|main;foo;bar|3|453510869|
|main;foobar|4|5351086|
|main;foo;runtime.selectgo|5|867549417|
|main;foo;bar;sync.(*Mutex).Lock|3|453510869|
|main;foobar;runtime.chanrecv1|4|5351086|
### Block Profiler Implementation