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portlist: reduce allocs on Linux

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Notably, it no longer allocates proportional to the number of open
sockets on the machine. Any alloc reduction numbers are a little
contrived with such a reduction but e.g. on a machine with 50,000
connections open:

name          old time/op    new time/op    delta
ParsePorts-6    57.7ms ± 6%    32.8ms ± 3%   -43.04%  (p=0.000 n=9+10)

name          old alloc/op   new alloc/op   delta
ParsePorts-6    24.0MB ± 0%     0.0MB ± 0%  -100.00%  (p=0.000 n=10+9)

name          old allocs/op  new allocs/op  delta
ParsePorts-6      100k ± 0%        0k ± 0%   -99.99%  (p=0.000 n=10+10)

Updates tailscale/corp#2566

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
2021-09-11 16:45:12 -07:00
committed by Brad Fitzpatrick
parent 4f648e6fcc
commit 64e9ce8df1
2 changed files with 54 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files
portlist/portlist_linux_test.go
+35
View File
@@ -7,6 +7,7 @@ package portlist
import (
"bufio"
"bytes"
"io"
"testing"
"github.com/google/go-cmp/cmp"
@@ -65,3 +66,37 @@ func TestParsePorts(t *testing.T) {
})
}
}
func BenchmarkParsePorts(b *testing.B) {
b.ReportAllocs()
var contents bytes.Buffer
contents.WriteString(` sl local_address remote_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000000000000000000001000000:0277 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 35720 1 0000000000000000 100 0 0 10 0
1: 00000000000000000000000000000000:1F91 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000 1000 0 142240557 1 0000000000000000 100 0 0 10 0
2: 00000000000000000000000000000000:0016 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 34064 1 0000000000000000 100 0 0 10 0
`)
for i := 0; i < 50000; i++ {
contents.WriteString(" 3: 69050120005716BC64906EBE009ECD4D:D506 0047062600000000000000006E171268:01BB 01 00000000:00000000 02:0000009E 00000000 1000 0 151042856 2 0000000000000000 21 4 28 10 -1\n")
}
want := []Port{
{Proto: "tcp", Port: 8081, inode: "socket:[142240557]"},
{Proto: "tcp", Port: 22, inode: "socket:[34064]"},
}
r := bytes.NewReader(contents.Bytes())
br := bufio.NewReader(&contents)
b.ResetTimer()
for i := 0; i < b.N; i++ {
r.Seek(0, io.SeekStart)
br.Reset(r)
got, err := parsePorts(br, "tcp")
if err != nil {
b.Fatal(err)
}
if len(got) != 2 || got[0].Port != 8081 || got[1].Port != 22 {
b.Fatalf("wrong result:\n got %+v\nwant %+v", got, want)
}
}
}