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pkg/fileutils: GetTotalUsedFds: reduce allocations

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Use File.Readdirnames instead of os.ReadDir, as we're only interested in
the number of files, and results don't have to be sorted.

Before:

    BenchmarkGetTotalUsedFds-5   	  149272	      7896 ns/op	     945 B/op	      20 allocs/op

After:

    BenchmarkGetTotalUsedFds-5   	  153517	      7644 ns/op	     408 B/op	      10 allocs/op

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit eaa9494b71)
Resolved conflicts:
	pkg/fileutils/fileutils_linux.go
Signed-off-by: Bjorn Neergaard <bjorn.neergaard@docker.com>
This commit is contained in:
Sebastiaan van Stijn 2023-06-29 15:50:02 +02:00 committed by Bjorn Neergaard
parent 55c8d163d7
commit 6c4adc0037
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1 changed files with 20 additions and 5 deletions
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25
pkg/fileutils/fileutils_linux.go
View file

@ -2,6 +2,7 @@ package fileutils
import (
"fmt"
"io"
"os"
"github.com/sirupsen/logrus"
@ -10,10 +11,24 @@ import (
// GetTotalUsedFds Returns the number of used File Descriptors by
// reading it via /proc filesystem.
func GetTotalUsedFds() int {
if fds, err := os.ReadDir(fmt.Sprintf("/proc/%d/fd", os.Getpid())); err != nil {
logrus.Errorf("Error opening /proc/%d/fd: %s", os.Getpid(), err)
} else {
return len(fds)
}
name := fmt.Sprintf("/proc/%d/fd", os.Getpid())
f, err := os.Open(name)
if err != nil {
logrus.WithError(err).Error("Error listing file descriptors")
return -1
}
defer f.Close()
var fdCount int
for {
names, err := f.Readdirnames(100)
fdCount += len(names)
if err == io.EOF {
break
} else if err != nil {
logrus.WithError(err).Error("Error listing file descriptors")
return -1
}
}
return fdCount
}