@@ -52,6 +52,28 @@ the system-installed version), using `which sqlite3`. Also, be sure that you've added your source install prefix (usually /usr/local) to /etc/ld.so.conf (or its moral equivalent) and that you've run /sbin/ldconfig. +== Thread safety + +SQLite 3 is not designed for concurrent use of a single database handle across +multiple threads. Therefore, to prevent segfaults, Geocoder::US::Database +implements a global mutex that wraps all database access. The use of this mutex +will ensure stability in multi-threaded applications, but incurs a performance +penalty. However, since the database is read-only from Ruby, there's no reason +in principle why multi-threaded apps can't each have their own database handle. + +To disable the mutex for better performance, you can do the following: + + * Read the following and make sure you understand them: + * http://www.sqlite.org/faq.html#q6 + * http://www.sqlite.org/cvstrac/wiki?p=MultiThreading + * Make sure you have compiled SQLite 3 with thread safety enabled. + * Instantiate a separate Geocoder::US::Database object for *each* thread + in your Ruby script, and pass :threadsafe => true to new() to disable mutex + synchronization. + +Per the SQLite 3 documentation, do *not* attempt to retain a +Geocoder::US::Database object across a fork! "Problems will result if you do." + == Building Geocoder::US Unpack the source and run 'make'. This will compile the SQLite 3 extension README.txt aa14c75b53a60a873539977a0e547c9f5e46b957 Schuyler Erle sderle@goldman.(none) http://github.com/geocommons/geocoder/commit/565a523d20c13a58cfc50f37f92cfb7662b85eb1 565a523d20c13a58cfc50f37f92cfb7662b85eb1 2009-07-21T18:20:47-07:00 2009-07-21T18:20:47-07:00 Note on thread safety in the README. 7afae0f5f0745d0d00d271bab1830c4d082cb0a8 Schuyler Erle sderle@goldman.(none)