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In the original design for parallel dump, worker processes reported errors by sending them up to the master process, which would print the messages. This is unworkably fragile for a couple of reasons: it risks deadlock if a worker sends an error at an unexpected time, and if the master has already died for some reason, the user will never get to see the error at all. Revert that idea and go back to just always printing messages to stderr. This approach means that if all the workers fail for similar reasons (eg, bad password or server shutdown), the user will see N copies of that message, not only one as before. While that's slightly annoying, it's certainly better than not seeing any message; not to mention that we shouldn't assume that only the first failure is interesting. An additional problem in the same area was that the master failed to disable SIGPIPE (at least until much too late), which meant that sending a command to an already-dead worker would cause the master to crash silently. That was bad enough in itself but was made worse by the total reliance on the master to print errors: even if the worker had reported an error, you would probably not see it, depending on timing. Instead disable SIGPIPE right after we've forked the workers, before attempting to send them anything. Additionally, the master relies on seeing socket EOF to realize that a worker has exited prematurely --- but on Windows, there would be no EOF since the socket is attached to the process that includes both the master and worker threads, so it remains open. Make archive_close_connection() close the worker end of the sockets so that this acts more like the Unix case. It's not perfect, because if a worker thread exits without going through exit_nicely() the closures won't happen; but that's not really supposed to happen. This has been wrong all along, so back-patch to 9.3 where parallel dump was introduced. Report: <2458.1450894615@sss.pgh.pa.us> |
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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 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. 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/.