From f0a2da583a01822958bf75c62319e3c0794fbeb9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20Geisend=C3=B6rfer?= <felix@felixge.de>
Date: Tue, 9 Feb 2021 21:18:50 +0100
Subject: [PATCH] Add simple block bias example

---
 examples/block-bias/block.pb.gz | Bin 0 -> 456 bytes
 examples/block-bias/go.mod      |   5 +++
 examples/block-bias/go.sum      |   2 +
 examples/block-bias/main.go     |  75 ++++++++++++++++++++++++++++++++
 4 files changed, 82 insertions(+)
 create mode 100644 examples/block-bias/block.pb.gz
 create mode 100644 examples/block-bias/go.mod
 create mode 100644 examples/block-bias/go.sum
 create mode 100644 examples/block-bias/main.go

diff --git a/examples/block-bias/block.pb.gz b/examples/block-bias/block.pb.gz
new file mode 100644
index 0000000000000000000000000000000000000000..09e0779997729d70d19fd780739968d70ca4bda8
GIT binary patch
literal 456
zcmV;(0XP01iwFP!00004|0K;ZixfW?$MOH{WNx3^J@y}jlfi14MmX4n4Ty@^s0+RU
z8yn4LpBcj?PmUzBuCGCkyL$sxf~Cl{*9dkNT8kFG3@gR4dW!G!;rEn5!AH-F$#5qO
zO3oS%Mg9KW1vC{D{CCNVBY=Webv55>{)bV0_3aWG1|$AxNFzS3$8%^7p{(D2A5zKh
zHVhbVhKG{x*ZXrg0$_YnPv&rK#=nmF)vq_7%Sl;`%H|MQ{prUgGz=<!zhSV)Z}Pvh
z6`$7Af$s5x`e2}6#{BH;^dDu9&o4gyJU@N?;ra~*#hpU^r=})QM#?r&Qk4lkWmRp^
z=~rq>nnFSoXp<C=J!R`rBy?zU7t}r3rzl-8+R2CLoQ|>!aw(R##O-HG>FgSJXk>~;
z#-6hEC=)s~S#&|wURx5$`rhe`4_q+Et1VJaYAv56j7hfW>`ruO6VfJNY%$6%$P|t2
zY<|(Ng$Z7^=<KdT*@eYP46St-7Zfrki9792945JT!5lBvRwwDTCD8>n^V*U~F1%cA
yk+Pb3ZArwQMB9^Ds+rf8M5|L?ZIQB?d2LC=o<!S|QGWse0RR74@&``{0ssKyTHJ5|

literal 0
HcmV?d00001

diff --git a/examples/block-bias/go.mod b/examples/block-bias/go.mod
new file mode 100644
index 0000000..08e0478
--- /dev/null
+++ b/examples/block-bias/go.mod
@@ -0,0 +1,5 @@
+module github.com/felixge/go-profiler-notes/examples/block-bias
+
+go 1.15
+
+require golang.org/x/sync v0.0.0-20201207232520-09787c993a3a
diff --git a/examples/block-bias/go.sum b/examples/block-bias/go.sum
new file mode 100644
index 0000000..5f7eb37
--- /dev/null
+++ b/examples/block-bias/go.sum
@@ -0,0 +1,2 @@
+golang.org/x/sync v0.0.0-20201207232520-09787c993a3a h1:DcqTD9SDLc+1P/r1EmRBwnVsrOwW+kk2vWf9n+1sGhs=
+golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
diff --git a/examples/block-bias/main.go b/examples/block-bias/main.go
new file mode 100644
index 0000000..1dd12dc
--- /dev/null
+++ b/examples/block-bias/main.go
@@ -0,0 +1,75 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"sync"
+	"time"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+var (
+	fastEventDuration = 1 * time.Millisecond
+	slowEventDuration = 1 * fastEventDuration
+)
+
+func run() error {
+	runtime.SetBlockProfileRate(int(slowEventDuration.Nanoseconds()))
+
+	var (
+		done = make(chan struct{})
+		wg   = &sync.WaitGroup{}
+	)
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		slowEvent(done)
+	}()
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		fastEvent(done)
+	}()
+	time.Sleep(1 * time.Second)
+	close(done)
+	wg.Wait()
+
+	f, err := os.Create("block.pb.gz")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	if err := pprof.Lookup("block").WriteTo(f, 0); err != nil {
+		return err
+	}
+	return nil
+}
+
+func slowEvent(done chan struct{}) error {
+	return simulateBlockEvents(slowEventDuration, done)
+}
+
+func fastEvent(done chan struct{}) error {
+	return simulateBlockEvents(fastEventDuration, done)
+}
+
+func simulateBlockEvents(duration time.Duration, done chan struct{}) error {
+	ticker := time.NewTicker(duration)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			// do nothing
+		case <-done:
+			return nil
+		}
+	}
+}