Re: [PATCH] sha1_file: introduce close_one_pack() to close packs on fd pressure

Brandon Casey [off-list ref] writes:

From: Brandon Casey <redacted>

When the number of open packs exceeds pack_max_fds, unuse_one_window()
is called repeatedly to attempt to release the least-recently-used
pack windows, which, as a side-effect, will also close a pack file
after closing its last open window.  If a pack file has been opened,
but no windows have been allocated into it, it will never be selected
by unuse_one_window() and hence its file descriptor will not be
closed.  When this happens, git may exceed the number of file
descriptors permitted by the system.

An interesting find.  The patch from a cursory look reads OK.

Thanks.

This is not likely to occur during upload-pack since upload-pack
reads each object from the pack so that it can peel tags and
advertise the exposed object.

Another interesting find.  Perhaps there is a room for improvements,
as packed-refs file knows what objects the tags peel to?  I vaguely
recall Peff was actively reducing the object access during ref
enumeration in not so distant past...