#include <hallo.h> After a heated private discussion, the main cause of the problem seems to be a shortcoming in the metadata update concept. But like with all big trouble there is no single cause but multiple issues appearing harmless in the beginning.
First, unlike with non-volatile files, apt-cacher-ng prefers to make an online connection to check whether a volatile (i.e. metadata/index file) was recently modified on the server. An extra connection is avoided if a second client connected to proxy and requests the same file while it's being downloaded from the remote machine and transfered to another user (i.e. the new client hits a "hot" cache file descriptor). In other cases a new connection to the mirror is opened, however if there were no updates then only a response header and maybe one byte of data. So the waste ammount wasted data itself is negligible (IMHO) but it still creates some load and spams the logs of the mirror machine. Now, in a scenario when a user configures dozens of local systems to run "apt-get update" almost at the same moment (almost=not perfectly) and doing this regularly (like every twenty minutes) then the time span between the different requests is long enough to complete the previous request of this file, and therefore close the cache file descriptor before the next client requests appears (after a couple of seconds), leading to the situation described above. The suggested workaround is adding an artificial timer, extending the lifetime of the temporary state descriptors for volatile files. Doing this, the same file should not be downloaded from the server more often then once in a certain time period. Empirically chosen value is seventeen seconds but that is subject to change. Patched packages (0.5.8* -> Sid, 0.5.1* -> Squeeze) can be found at http://apt-cacher-ng.alioth.debian.org/unreleased/ -- I cannot discover unexpected side effects yet but a little bit more testing should be done before suggesting it for Squeeze inclusion. Feedback would be much appreciated. Regards, Eduard. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
