On 10/6/22 11:55, Vít Ondruch wrote:
Dne 06. 10. 22 v 9:18 Otto Liljalaakso napsal(a):
Miro Hrončok kirjoitti 6.10.2022 klo 2.33:
On 06. 10. 22 1:21, Otto Liljalaakso wrote:
Recently, I have run into some cases where file dependencies like
Requires: /usr/bin/foo are used.
In a recent thread on this mailing list [1],
it is mentioned that such Requires should be avoided,
because resolving file dependencies requires a large amount of memory.
I don't believe that resolving file-Requires from directories listed
at [2] from your email is more memory hungry. Where exactly was that
said?
[1]:
https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx/message/CRREDQUPPJYWVRMA4DOKYU2KZZLKC4D5/
[2]:
https://docs.fedoraproject.org/en-US/packaging-guidelines/#_file_and_directory_dependencies
Maybe I should have re-read the thread closely before posting,
because the most relevant message is this [3]:
"
The discussion in the bug indicates that this memory growth is related to
loading of the full filepath dataset. We have been discussing splitting
out the non-primary-filepath-data (i.e. paths that are not /etc,
/usr/bin,
/usr/sbin), out into a separate lazilly-loaded file. If we manage to do
that, we'll kill two birds with one stone:
- initial download of repo metadata on every freakin' dnf operation can
go down from 80 to 20 MB
- the peak memory use will go down
"
Which exactly confirms what you say.
I am still wondering a bit if there is something else bad about file
dependencies?
If I am not mistaken, in the YUM days, the file list was split into two
parts. One list contained several high profile directories such as
/usr/bin [1] while the other contained everything. By default YUM have
not loaded the full file list by default, just the short one. The data
were not loaded by default. But AFAIK, DNF always loads everything and
it does not look that this would change. This is one BZ which comes to
my mind for a reference: https://bugzilla.redhat.com/show_bug.cgi?id=968006
IOW for your example, the file dependency was always supported (and IMO
preferable). It probably does not matter these days, unless you really
consider memory consumption (and I don't think we should generally avoid
the file dependencies just on the base of memory consumption).
In the yum days, certain locations of the file list, such as /usr/bin
were embedded in the main data. They're still there, look for <file>
entries in primary.xml.
I don't know if libsolv/dnf look at that data at all, the architecture
is so drastically different compared to yum that the seemingly obvious
lazy loading may well be very very difficult to achieve. I remember that
being the case with apt-rpm (if anybody remembers *that* old beast)
whose operational model was closer to libsolv than yum.
- Panu -
- Panu -
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