Control: severity 795284 important On Tue, 25 Aug 2015 15:04:29 +0100 Mark Hindley <[email protected]> wrote: > package apt-cacher > reassign 795284 apt > thanks > > I have looked at this some more and I think apt-cacher is following the spec > correctly. It seems as if apt-get doesn't realise that the 416 response with > the > Content-Range denominator equal to the size it already has indicates the file > is > complete. > > So I am going to reassign to apt. > > Apt team, if I have got this analysis wrong, sorry, do point out my error and > assign > back.
Dear apt team, I came recently to erratical behavior of apt with apt-cacher-ng (not apt-cacher but similar). Checking the wireshark trace, I see strange things, see below. For me, what apt's http client is doing there DOES NOT MAKE MUCH SENSE. The ancient version, like 10 years ago, used a very simple and effective trick. It specified If-Range but also a Range which started one byte _before_ the previous body length. So the server could either return just a byte or start returning a completely new resource body with a 200 response, no extra rounds needed. What does the current version do? It requests the file but the with If-Range (which is okay) and Range which starts AFTER the body. This obviously causes a code 416 even if the response body hasn't changed. In response, apt makes another request, with "If-Modified-Since" from a day ago - so I guess it has another version in cache, which it takes as replacement now. It also does not specify the Range. So I guess the issue 795284 is mostly solved but not fully, we got another pointless behavior now. So, the current version behaves better than in 2015, but still worse than ~10 years ago. Please restore the original algorithm, which refetched the last byte. This causes less bandwith waste than doing a second request which will almost always become necessary. (local trace, input/output interleaved but you see the point). GET http://ftp.de.debian.org/debian/dists/testing/InRelease HTTP/1.1 Host: ftp.de.debian.org Cache-Control: max-age=0 Accept: text/* Range: bytes=128490- If-Range: Fri, 08 Oct 2021 14:16:00 GMT User-Agent: Debian APT-HTTP/1.3 (2.3.9) HTTP/1.1 416 Requested Range Not Satisfiable Content-Length: 512 Content-Type: text/html Date: Fri, 08 Oct 2021 18:26:45 GMT Server: Debian Apt-Cacher NG/3.7.3 <!DOCTYPE html> ... href="http://www.unix-ag.uni-kl.de/~bloch/acng/";>Apt-Cacher NG homepage</a></address></html> GET http://ftp.de.debian.org/debian/dists/testing/InRelease HTTP/1.1 Host: ftp.de.debian.org Cache-Control: max-age=0 Accept: text/* If-Modified-Since: Thu, 07 Oct 2021 14:15:24 GMT User-Agent: Debian APT-HTTP/1.3 (2.3.9) HTTP/1.1 200 OK Content-Type: octet/stream Last-Modified: Fri, 08 Oct 2021 14:16:00 GMT Content-Length: 128490 X-Original-Source: http://deb.debian.org/debian/dists/testing/InRelease Date: Fri, 08 Oct 2021 18:26:45 GMT Server: Debian Apt-Cacher NG/3.7.3 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Origin: Debian Label: Debian ... Best regards, Eduard.
