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>
pkg/ is a collection of utility packages used by the Moby project without being specific to its internals.
Utility packages are kept separate from the moby core codebase to keep it as small and concise as possible.
If some utilities grow larger and their APIs stabilize, they may be moved to their own repository under the
Moby organization, to facilitate re-use by other projects. However that is not the priority.
The directory pkg is named after the same directory in the camlistore project. Since Brad is a core
Go maintainer, we thought it made sense to copy his methods for organizing Go code :) Thanks Brad!
Because utility packages are small and neatly separated from the rest of the codebase, they are a good
place to start for aspiring maintainers and contributors. Get in touch if you want to help maintain them!
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