Configure the number of additional mutexes to allocate.
</p>
<p>
If an application will allocate mutexes for its own use,
the <codeclass="methodname">DB_ENV->mutex_set_increment()</code> method is used to add a
number of mutexes to the default allocation.
</p>
<p>
Calling the <codeclass="methodname">DB_ENV->mutex_set_increment()</code> method discards any value
previously set using the <codeclass="methodname">DB_ENV->mutex_set_max()</code> method.
</p>
<p>
The database environment's number of additional mutexes may also be
configured using the environment's <ahref="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG"class="olink">DB_CONFIG</a> file. The
syntax of the entry in that file is a single line with the string
"mutex_set_increment", one or more whitespace characters, and the
number of additional mutexes. Because the <ahref="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG"class="olink">DB_CONFIG</a> file is
read when the database environment is opened, it will silently
overrule configuration done before that time.
</p>
<p>
The <codeclass="methodname">DB_ENV->mutex_set_increment()</code> method configures a database
environment, not only operations performed using the specified
<aclass="link"href="env.html"title="Chapter5. The DB_ENV Handle">DB_ENV</a> handle.
</p>
<p>
The <codeclass="methodname">DB_ENV->mutex_set_increment()</code> method may not be called after the
<aclass="xref"href="envopen.html"title="DB_ENV->open()">DB_ENV->open()</a> method is
called. If the database environment already exists when
<aclass="xref"href="envopen.html"title="DB_ENV->open()">DB_ENV->open()</a> is called, the
information specified to <codeclass="methodname">DB_ENV->mutex_set_increment()</code> will be
ignored.
</p>
<p>
The <codeclass="methodname">DB_ENV->mutex_set_increment()</code><span>
<span>
method returns a non-zero error value on failure and 0 on success.
