On Thu, Mar 12, 2009 at 5:18 AM, Xavier
On Thu, Mar 12, 2009 at 9:19 AM, Allan McRae
wrote: Hi,
You have probably heard about this: http://linux.slashdot.org/article.pl?sid=09/03/11/2031231
Here is the link to the bug report that describes the cause of the problem: https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/54
A key part of the bug report comment... Applications are expected to use fsync() or fdatasync(), and if that impacts their performance too much, to use a single berkdb or other binary database file, and not do something stupid with hundreds of tiny text files that only hold a few bytes of data in each text file.
Hmmm... something sound familiar there? So what should we do? Maybe, add some sort of syncing after a db write. But then after each file or just at the end of the transaction?
If I remember correctly, the code does this : pkg1 : extract files ; write db entry pkg2 : extract files ; write db entry etc ..
So yeah, it could make sense to sync after each db write to have a consistent database after each package install.
Adding an fsync() in the write_db_entry() call would probably make sense. However, note the funny part here- if we sync our DB entries, and then your machine gets powered off, you might end up with a DB that got committed but files in the package never actually got written to disk. -Dan