I recently upgraded my system from 14.10 to the new version (I know, my second mistake, the first one was the upgrade to 14.10), 15.04. Let's say that since I did that, last Friday, I didn't notice major drawbacks (except for some strange lock-screen issue) until today.
Yesterday evening I forgot to shut down the computer and today after I logged in I started to see some strange increased CPU usage. There was a /usr/lib/apt/methods/http process that took 100% of the CPU constantly. Seeing this, I thought doing a software update (graphically) would terminate the process, but instead I got a message like apt-get cannot exit, or something like that. I thought perhaps some other process locked apt, so I tried to unlock it by removing the lock files /var/lib/apt/lists/lock and /var/cache/apt/archives/lock but nothing changed, the process was still running.
Then I thought perhaps a reboot will fix the issue, so I rebooted the computer. After the reboot the /usr/lib/apt/methods/http process was indeed gone, so I tried updating the software sources manually to see what was going on. When I ran apt-get update I noticed that at the end the update is stuck with a line such as 100% [15 Packages 25.6 GB/25.6 GB 100%], where the total amount of data (the size in GB) is increasing, it does not stop. I had to interrupt the command because I didn't know what it was doing.
What should be the problem ? How can I fix this ?
/etc/apt/sources.listand everything in/etc/apt/sources.list.dfordebstatements that look suspicious, or edit your question and add all thedebstatements.deblines except one, and see where theapt-get updatecommand gets stuck. That includes any lines in thesources.list.dfolder. To narrow it down, do a "binary search" - comment the first half, if that gets stuck the harmfuldebline must be in the second half, etc.