mirror of
https://github.com/berkeleydb/libdb.git
synced 2024-11-16 17:16:25 +00:00
97 lines
4.4 KiB
HTML
97 lines
4.4 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||
<title>Multi-threaded and Multi-process Applications</title>
|
||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Transaction Processing" />
|
||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction" />
|
||
<link rel="prev" href="apireq.html" title="Application Requirements" />
|
||
<link rel="next" href="recovery-intro.html" title="Recoverability" />
|
||
</head>
|
||
<body>
|
||
<div xmlns="" class="navheader">
|
||
<div class="libver">
|
||
<p>Library Version 11.2.5.3</p>
|
||
</div>
|
||
<table width="100%" summary="Navigation header">
|
||
<tr>
|
||
<th colspan="3" align="center">Multi-threaded
|
||
<span xmlns="http://www.w3.org/1999/xhtml">and Multi-process</span>
|
||
Applications</th>
|
||
</tr>
|
||
<tr>
|
||
<td width="20%" align="left"><a accesskey="p" href="apireq.html">Prev</a> </td>
|
||
<th width="60%" align="center">Chapter 1. Introduction</th>
|
||
<td width="20%" align="right"> <a accesskey="n" href="recovery-intro.html">Next</a></td>
|
||
</tr>
|
||
</table>
|
||
<hr />
|
||
</div>
|
||
<div class="sect1" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h2 class="title" style="clear: both"><a id="multithread-intro"></a>Multi-threaded
|
||
<span>and Multi-process</span>
|
||
Applications</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
DB is designed to support multi-threaded <span>and
|
||
multi-process</span> applications, but their usage means
|
||
you must pay careful attention to issues of concurrency.
|
||
Transactions help your application's concurrency by providing various levels of
|
||
isolation for your threads of control. In addition, DB
|
||
provides mechanisms that allow you to detect and respond to
|
||
deadlocks.
|
||
</p>
|
||
<p>
|
||
<span class="emphasis"><em>Isolation</em></span> means that database modifications made by
|
||
one transaction will not normally be seen by readers from another
|
||
transaction until the first commits its changes. Different threads
|
||
use different transaction handles, so
|
||
this mechanism is normally used to provide isolation between
|
||
database operations performed by different threads.
|
||
</p>
|
||
<p>
|
||
Note that DB supports different isolation levels. For example,
|
||
you can configure your application to see uncommitted reads, which means
|
||
that one transaction can see data that has been modified but not yet
|
||
committed by another transaction. Doing this might mean your
|
||
transaction reads data "dirtied" by another transaction,
|
||
but which subsequently might change before that
|
||
other transaction commits its changes.
|
||
On the other hand, lowering your isolation
|
||
requirements means that your application can experience
|
||
improved throughput due to reduced lock contention.
|
||
</p>
|
||
<p>
|
||
For more information on concurrency, on managing isolation
|
||
levels, and on deadlock detection, see <a class="xref" href="txnconcurrency.html" title="Chapter 4. Concurrency">Concurrency</a>.
|
||
</p>
|
||
</div>
|
||
<div class="navfooter">
|
||
<hr />
|
||
<table width="100%" summary="Navigation footer">
|
||
<tr>
|
||
<td width="40%" align="left"><a accesskey="p" href="apireq.html">Prev</a> </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="u" href="introduction.html">Up</a>
|
||
</td>
|
||
<td width="40%" align="right"> <a accesskey="n" href="recovery-intro.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">Application Requirements </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top"> Recoverability</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</body>
|
||
</html>
|