Linux 6.2 and up (commit [f1f1f2569901ec5b9d425f2e91c09a0e320768f3][1])
provides a fast path for the number of open files for the process.
From the [Linux docs][2]:
> The number of open files for the process is stored in 'size' member of
> `stat()` output for /proc/<pid>/fd for fast access.
[1]: f1f1f25699
[2]: https://docs.kernel.org/filesystems/proc.html#proc-pid-fd-list-of-symlinks-to-open-files
This patch adds a fast-path for Kernels that support this, and falls back
to the slow path if the Size fields is zero.
Comparing on a Fedora 38 (kernel 6.2.9-300.fc38.x86_64):
Before/After:
go test -bench ^BenchmarkGetTotalUsedFds$ -run ^$ ./pkg/fileutils/
BenchmarkGetTotalUsedFds 57264 18595 ns/op 408 B/op 10 allocs/op
BenchmarkGetTotalUsedFds 370392 3271 ns/op 40 B/op 3 allocs/op
Note that the slow path has 1 more file-descriptor, due to the open
file-handle for /proc/<pid>/fd during the calculation.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit ec79d0fc05)
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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