[common][linux]: improve readlines performance.

internal/common/common.go

@@ -109,9 +109,14 @@ func ReadFile(filename string) (string, error) {
 }
 
 // ReadLines reads contents from a file and splits them by new lines.
-// A convenience wrapper to ReadLinesOffsetN(filename, 0, -1).
+// Please do not use this function on Windows platform.
 func ReadLines(filename string) ([]string, error) {
-	return ReadLinesOffsetN(filename, 0, -1)
+	bytes, err := os.ReadFile(filename)
+	if err != nil {
+		return []string{""}, err
+	}
+	lines := strings.Split(strings.Trim(string(bytes), "\n"), "\n")
+	return lines, nil
 }
 
 // ReadLinesOffsetN reads contents from file and splits them by new line.

internal/common/common_linux.go

@@ -89,7 +89,8 @@ func BootTimeWithContext(ctx context.Context) (uint64, error) {
 	}
 
 	if statFile == "stat" {
-		for _, line := range lines {
+		for i := len(lines) - 1; i > 0; i-- {
+			line := lines[i]
 			if strings.HasPrefix(line, "btime") {
 				f := strings.Fields(line)
 				if len(f) != 2 {

internal/common/common_linux_test.go

@@ -0,0 +1,22 @@
+//go:build linux
+// +build linux
+
+package common
+
+import (
+	"context"
+	"testing"
+
+	"github.com/shirou/gopsutil/v3/common"
+)
+
+func BenchmarkBootTimeWithManyCPUs(b *testing.B) {
+	ctx := context.WithValue(context.Background(),
+		common.EnvKey,
+		common.EnvMap{common.HostProcEnvKey: "testdata/linux/issue_1514"},
+	)
+
+	for i := 0; i < b.N; i++ {
+		BootTimeWithContext(ctx)
+	}
+}

internal/common/testdata/linux/issue_1514/stat

@@ -0,0 +1,88 @@
+cpu  768944 10288 1072079 11045715258 3486 0 5444 0 0 0
+cpu0 8786 70 6308 137988080 26 0 67 0 0 0
+cpu1 9068 30 6191 138072341 59 0 11 0 0 0
+cpu2 65109 159 171353 137907618 83 0 8 0 0 0
+cpu3 24084 118 40891 137992666 88 0 8 0 0 0
+cpu4 43038 444 109352 137978323 83 0 4 0 0 0
+cpu5 21472 193 40224 138025036 82 0 0 0 0 0
+cpu6 42410 118 123254 137981039 92 0 3 0 0 0
+cpu7 18037 232 33534 138039186 101 0 5 0 0 0
+cpu8 31662 186 72772 138013182 98 0 4 0 0 0
+cpu9 13657 181 17251 138023478 91 0 221 0 0 0
+cpu10 31512 159 74950 138015049 40 0 0 0 0 0
+cpu11 12116 472 16357 138037994 71 0 166 0 0 0
+cpu12 21121 85 43973 138039462 63 0 4 0 0 0
+cpu13 10251 27 10354 138021006 59 0 0 0 0 0
+cpu14 18905 280 40738 138048357 50 0 5 0 0 0
+cpu15 10326 360 10793 138065576 47 0 3 0 0 0
+cpu16 11191 100 13201 138062883 52 0 0 0 0 0
+cpu17 8028 107 7053 138066687 54 0 0 0 0 0
+cpu18 7964 102 7473 138082226 43 0 6 0 0 0
+cpu19 7326 158 5075 138084645 27 0 1 0 0 0
+cpu20 7577 4 6287 138079436 41 0 0 0 0 0
+cpu21 7813 12 6644 138067886 84 0 131 0 0 0
+cpu22 6736 117 5078 138085923 19 0 2 0 0 0
+cpu23 7123 128 5150 138086066 21 0 3 0 0 0
+cpu24 9399 13 6703 138082336 24 0 39 0 0 0
+cpu25 8955 45 6350 138083373 26 0 0 0 0 0
+cpu26 6441 83 4730 138088400 31 0 2 0 0 0
+cpu27 6157 25 4148 138089297 27 0 6 0 0 0
+cpu28 6401 9 4586 138087528 44 0 1 0 0 0
+cpu29 6391 17 4265 138087849 46 0 21 0 0 0
+cpu30 6286 461 3308 138090520 50 0 0 0 0 0
+cpu31 6094 104 3068 138091314 86 0 0 0 0 0
+cpu32 6022 108 3822 138089008 19 0 1 0 0 0
+cpu33 5909 73 3729 138088729 11 0 1 0 0 0
+cpu34 6820 294 3541 138088142 6 0 1 0 0 0
+cpu35 6616 129 3347 138090230 8 0 0 0 0 0
+cpu36 6206 107 4706 138083252 9 0 1 0 0 0
+cpu37 6584 28 2864 138085803 23 0 1 0 0 0
+cpu38 6220 131 3001 138091331 37 0 2 0 0 0
+cpu39 5486 217 2772 138092221 38 0 2 0 0 0
+cpu40 5842 31 2824 138093761 14 0 0 0 0 0
+cpu41 6105 125 2923 138093217 17 0 0 0 0 0
+cpu42 5204 44 3539 138091542 12 0 1 0 0 0
+cpu43 5839 32 3417 138091082 10 0 4 0 0 0
+cpu44 5615 19 3980 138092487 22 0 4 0 0 0
+cpu45 6026 424 4100 138091306 19 0 0 0 0 0
+cpu46 5527 209 3688 138094125 12 0 0 0 0 0
+cpu47 5336 109 3033 138094396 12 0 3 0 0 0
+cpu48 5494 103 2653 138096147 2 0 1 0 0 0
+cpu49 5218 30 2393 138097187 5 0 0 0 0 0
+cpu50 5484 239 2130 138096460 8 0 0 0 0 0
+cpu51 5043 34 2446 138096773 15 0 0 0 0 0
+cpu52 5498 27 2971 138095154 8 0 12 0 0 0
+cpu53 5181 43 2634 138087718 8 0 2 0 0 0
+cpu54 4988 36 2976 138095457 4 0 0 0 0 0
+cpu55 5081 21 2344 138095338 7 0 0 0 0 0
+cpu56 4636 273 1897 138096693 12 0 2 0 0 0
+cpu57 4884 316 1935 138095963 15 0 3 0 0 0
+cpu58 4870 229 1745 138097331 6 0 1 0 0 0
+cpu59 4924 28 1746 138097999 7 0 5 0 0 0
+cpu60 4461 129 1955 138096954 361 0 0 0 0 0
+cpu61 5030 35 1930 138097414 460 0 0 0 0 0
+cpu62 4179 23 2157 138097375 9 0 5 0 0 0
+cpu63 4242 134 2235 138096928 10 0 8 0 0 0
+cpu64 6682 254 2108 138094052 4 0 3 0 0 0
+cpu65 4354 115 1743 138097071 3 0 0 0 0 0
+cpu66 4162 9 2496 138095759 7 0 0 0 0 0
+cpu67 3863 28 1960 138097697 6 0 5 0 0 0
+cpu68 13484 17 17176 137901816 109 0 4614 0 0 0
+cpu69 12515 17 14273 137980618 100 0 4 0 0 0
+cpu70 5085 74 3738 138092386 10 0 0 0 0 0
+cpu71 4792 14 3574 138093476 13 0 0 0 0 0
+cpu72 4943 167 2880 138090318 12 0 2 0 0 0
+cpu73 5333 17 4367 138089338 19 0 0 0 0 0
+cpu74 4909 5 2995 138076914 30 0 2 0 0 0
+cpu75 4817 256 3160 138072268 30 0 0 0 0 0
+cpu76 4146 233 2160 138096352 8 0 1 0 0 0
+cpu77 4598 474 1860 138096155 10 0 3 0 0 0
+cpu78 4733 34 2352 138094484 29 0 4 0 0 0
+cpu79 4488 164 2359 138094227 44 0 2 0 0 0
+intr 1136940775 0 1020438 49587864 0 0 0 210556659 0 0 0 0 0 867076724 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 609 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 51690 0 0 0 0 0 0 0 1 5604085 970576 914985 910669 70 33120 33768 24240 21358 14764 17850 12776 9795 8765 6098 7307 8012 15687 13640 7797 11437
+ctxt 1918526774
+btime 1691617230
+processes 501797
+procs_running 39
+procs_blocked 0
+softirq 272142382 51064 32640104 523 8408436 152655 0 4696 152439652 131 78445121

process/process_test.go

@@ -862,3 +862,9 @@ func BenchmarkProcessPpid(b *testing.B) {
 		p.Ppid()
 	}
 }
+
+func BenchmarkProcesses(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Processes()
+	}
+}