On Fri, May 4, 2012 at 12:21 PM, Paul Thomson <pault...@gmail.com> wrote:
> I am working on a tool that (among other things) can detect data > races, including file access races. I have detected a file race in > SQLite on the database file that appears to be real, although I am not > certain - I have no experience with SQLite. I compiled SQLite with: > #define SQLITE_THREADSAFE 2 > > I use a simple test case where two threads call opendb There is no such function "opendb()" in SQLite, either as an API or internal. Did you mean sqlite3_open()? > on the same > file, write into the same table and then close the database. The file > race appears to occur due to sqlite3PagerReadFileheader (as the > database is opened?) in one thread and pager_write_pagelist in the > other. It looks as though the page that was written was pgno 1. Can > any experts explain whether these two accesses are in fact > synchronised, or if the race is benign? > Each database connection will have its own page cache, so access to internal data structures need not be synchronized. Access to the disk file is synchronized using file locks - the exact workings of which depends on the operating system, which you have left unspecified. > > I am using sqlite-amalgamation-3071100. I will later upload the test > case, trace (showing all calls that are made by each thread) and the > stack trace for each thread when the race occurs, unless it becomes > obvious that the above functions cannot race. What is best way to > provide these files? (attachments? upload to a website and provide a > link?) > > Thanks, > Paul > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
