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It works on the principle of turning sockets into non-blocking, and then emulate blocking behaviour on top of that, while allowing signals to run. Signals are now implemented using an event instead of APCs, thus getting rid of the issue of APCs not being compatible with "old style" sockets functions. It also moves the win32 specific code away from pqsignal.h/c into port/win32, and also removes the "thread style workaround" of the APC issue previously in place. In order to make things work, a few things are also changed in pgstat.c: 1) There is now a separate pipe to the collector and the bufferer. This is required because the pipe will otherwise only be signalled in one of the processes when the postmaster goes down. The MS winsock code for select() must have some kind of workaround for this behaviour, but I have found no stable way of doing that. You really are not supposed to use the same socket from more than one process (unless you use WSADuplicateSocket(), in which case the docs specifically say that only one will be flagged). 2) The check for "postmaster death" is moved into a separate select() call after the main loop. The previous behaviour select():ed on the postmaster pipe, while later explicitly saying "we do NOT check for postmaster exit inside the loop". The issue was that the code relies on the same select() call seeing both the postmaster pipe *and* the pgstat pipe go away. This does not always happen, and it appears that useing WSAEventSelect() makes it even more common that it does not. Since it's only called when the process exits, I don't think using a separate select() call will have any significant impact on how the stats collector works. Magnus Hagander |
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| configure | ||
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| COPYRIGHT | ||
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| README | ||
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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 several language bindings, including C and Tcl. The JDBC, ODBC, C++, and Python interfaces have been moved to the PostgreSQL Projects Web Site at http://gborg.postgresql.org for separate maintenance. A Perl DBI/DBD driver is available from CPAN. 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 ftp://ftp.postgresql.org/pub/. For more information look at our web site located at http://www.postgresql.org/.