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At least on this architecture, it's very important to spin on a non-atomic instruction and only retry the atomic once it appears that it will succeed. To fix this, split TAS() into two macros: TAS(), for trying to grab the lock the first time, and TAS_SPIN(), for spinning until we get it. TAS_SPIN() defaults to same as TAS(), but we can override it when we know there's a better way. It's likely that some of the other cases in s_lock.h require similar treatment, but this is the only one we've got conclusive evidence for at present.
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: http://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Changes between all PostgreSQL releases are recorded in the file HISTORY. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.