93853eca94
This patch contains some optimizations I still had stashed when working
on eaa9494b71.
- Use the bytes package for handling the output of "lsof", instead of
converting to a string.
- Count the number of newlines in the output, instead of splitting the
output into a slice of strings. We're only interested in the number
of lines in the output.
- Use lsof's -F option to only print the file-descriptor for each line,
as we don't need other information.
- Use the -l, -n, and -P options to omit converting usernames, host names,
and port numbers.
From the [LSOF(8)][1] man-page:
-l This option inhibits the conversion of user ID numbers to
login names. It is also useful when login name lookup is
working improperly or slowly.
-n This option inhibits the conversion of network numbers to host
names for network files. Inhibiting conversion can make lsof run faster.
It is also useful when host name lookup is not working properly.
-P This option inhibits the conversion of port numbers to port names for network files.
Inhibiting the conversion can make lsof run a little faster.
It is also useful when host name lookup is not working properly.
Output looks something like;
lsof -lnP -Ff -p 39849
p39849
fcwd
ftxt
ftxt
f0
f1
f2
f3
f4
f5
f6
f7
f8
f9
f10
f11
Before/After:
BenchmarkGetTotalUsedFds-10 122 9479384 ns/op 10816 B/op 63 allocs/op
BenchmarkGetTotalUsedFds-10 154 7814697 ns/op 7257 B/op 60 allocs/op
[1]: https://opensource.apple.com/source/lsof/lsof-49/lsof/lsof.man.auto.html
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
25 lines
758 B
Go
25 lines
758 B
Go
package fileutils // import "github.com/docker/docker/pkg/fileutils"
|
|
|
|
import (
|
|
"bytes"
|
|
"os"
|
|
"os/exec"
|
|
"strconv"
|
|
)
|
|
|
|
// GetTotalUsedFds returns the number of used File Descriptors by executing
|
|
// "lsof -lnP -Ff -p PID".
|
|
//
|
|
// It uses the "-F" option to only print file-descriptors (f), and the "-l",
|
|
// "-n", and "-P" options to omit looking up user-names, host-names, and port-
|
|
// names. See [LSOF(8)].
|
|
//
|
|
// [LSOF(8)]: https://opensource.apple.com/source/lsof/lsof-49/lsof/lsof.man.auto.html
|
|
func GetTotalUsedFds() int {
|
|
output, err := exec.Command("lsof", "-lnP", "-Ff", "-p", strconv.Itoa(os.Getpid())).CombinedOutput()
|
|
if err != nil {
|
|
return -1
|
|
}
|
|
|
|
return bytes.Count(output, []byte("\nf")) // Count number of file descriptor fields in output.
|
|
}
|