2011-09-13 17:44:24 +00:00
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<title>Minor Change in Behavior of DB_MPOOLFILE->get</title>
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2012-11-14 21:35:20 +00:00
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<link rel="up" href="upgrade_4_8_toc.html" title="Chapter 13. Upgrading Berkeley DB 4.7 applications to Berkeley DB 4.8" />
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2011-09-13 17:44:24 +00:00
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<link rel="prev" href="upgrade_4_8_dpl.html" title="Registering DPL Secondary Keys" />
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2012-11-14 21:35:20 +00:00
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<p>Library Version 11.2.5.3</p>
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2011-09-13 17:44:24 +00:00
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<th colspan="3" align="center">Minor Change in Behavior of DB_MPOOLFILE->get</th>
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2012-11-14 21:35:20 +00:00
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<th width="60%" align="center">Chapter 13. Upgrading Berkeley DB 4.7 applications to Berkeley DB 4.8</th>
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2011-09-13 17:44:24 +00:00
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<h2 class="title" style="clear: both"><a id="upgrade_4_8_mpool"></a>Minor Change in Behavior of DB_MPOOLFILE->get</h2>
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</div>
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</div>
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</div>
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<p>
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DB 4.8 introduces some performance enhancements, based on the use
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of shared/exclusive latches instead of locks in some areas of the
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internal buffer management code. This change will affect how the
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<code class="classname">DB_MPOOL</code> interface handles dirty buffers.
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</p>
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<p> Because of these
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changes, <code class="methodname">DB_MPOOLFILE->get</code> will now
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acquire an exclusive latch on the buffer if
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the <code class="literal">DB_MPOOL_DIRTY</code>
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or <code class="literal">DB_MPOOL_EDIT</code> flags are specified. This
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could lead to an application deadlock if the application tries to
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fetch the buffer again, without an
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intervening <code class="methodname">DB_MPOOLFILE->put</code> call.
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</p>
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<p>
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If your application uses the <code class="literal">DB_MPOOL</code>
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interface, and especially the <code class="literal">DB_MPOOL_DIRTY</code>
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and <code class="literal">DB_MPOOL_EDIT</code> flags, you should review your
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code to ensure that this behavior change does not cause your
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application to deadlock.
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</p>
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<td width="40%" align="left"><a accesskey="p" href="upgrade_4_8_dpl.html">Prev</a> </td>
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<a accesskey="u" href="upgrade_4_8_toc.html">Up</a>
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<td width="40%" align="left" valign="top">Registering DPL Secondary Keys </td>
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Dropped Support for fcntl System Calls</td>
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</tr>
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