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<h2 class="title" style="clear: both"><a id="envset_thread_count"></a>DbEnv::set_thread_count()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::set_thread_count(u_int32_t count); </pre>
<p>
Declare an approximate number of threads in the database environment.
The <code class="methodname">DbEnv::set_thread_count()</code> method must be called prior to opening
the database environment if the
<a class="xref" href="envfailchk.html" title="DbEnv::failchk()">DbEnv::failchk()</a> method will
be used. The <code class="methodname">DbEnv::set_thread_count()</code> method does not set the
maximum number of threads but is used to determine memory sizing and
the thread control block reclamation policy.
</p>
<p>
If a process has not configured an <span class="bold"><strong>is_alive</strong></span> function from the
<a class="xref" href="envset_isalive.html" title="DbEnv::set_isalive()">DbEnv::set_isalive()</a>
method, and then attempts to join a database environment configured
for failure checking with the <a class="xref" href="envfailchk.html" title="DbEnv::failchk()">DbEnv::failchk()</a>,
<a class="xref" href="envset_thread_id.html" title="DbEnv::set_thread_id()">DbEnv::set_thread_id()</a>,
<a class="xref" href="envset_isalive.html" title="DbEnv::set_isalive()">DbEnv::set_isalive()</a> and
<code class="methodname">DbEnv::set_thread_count()</code> methods, the program may be unable to
allocate a thread control block and fail to join the environment.
<span class="bold"><strong>This is true of the standalone Berkeley DB
utility programs.</strong></span> To avoid problems when using the
standalone Berkeley DB utility programs with environments configured
for failure checking, incorporate the utility's functionality directly
in the application, or call the
<a class="xref" href="envfailchk.html" title="DbEnv::failchk()">DbEnv::failchk()</a> method
before running the utility.
</p>
<p>
The database environment's thread count may also be configured using
the environment's <a href="../../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
"set_thread_count", one or more whitespace characters, and the thread
count. Because the <a href="../../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 <code class="methodname">DbEnv::set_thread_count()</code> method configures operations performed
using the specified <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle, not all
operations performed on the underlying database environment.
</p>
<p>
The <code class="methodname">DbEnv::set_thread_count()</code> method may not be called after the
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method is
called.
</p>
<p>
The <code class="methodname">DbEnv::set_thread_count()</code> <span>
<span>
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1674974"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1674761"></a>count</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>count</strong></span> parameter is an approximate
thread count for the database environment.
</p>
</div>
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<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1675152"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::set_thread_count()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1675234"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If the method was called after <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>
was called; or if an invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1675235"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1674991"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a>
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