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| <a name="log.rationale.why_crash_on_term"></a><a class="link" href="why_crash_on_term.html" title="Why my application crashes on process termination when file sinks are used?">Why my application crashes |
| on process termination when file sinks are used?</a> |
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| <p> |
| There are known problems with <a href="http://www.boost.org/doc/libs/release/libs/filesystem/doc/index.htm" target="_top">Boost.Filesystem</a> |
| (for example, <a href="https://svn.boost.org/trac/boost/ticket/8642" target="_top">#8642</a> and <a href="https://svn.boost.org/trac/boost/ticket/9219" target="_top">#9219</a>), which affect Boost.Log file sink backends. |
| When the file sink is destroyed, it attempts to perform a final log file |
| rotation, which involves <a href="http://www.boost.org/doc/libs/release/libs/filesystem/doc/index.htm" target="_top">Boost.Filesystem</a> |
| for moving files. This typically happens when Boost.Log core is deinitialized, |
| at the global deinitialization stage, after leaving <code class="computeroutput"><span class="identifier">main</span><span class="special">()</span></code>. The crux of the problem is that <a href="http://www.boost.org/doc/libs/release/libs/filesystem/doc/index.htm" target="_top">Boost.Filesystem</a> |
| uses a global locale object internally to perform character code conversion |
| for <code class="computeroutput"><span class="identifier">path</span></code>s, and this locale |
| may get destroyed before Boost.Log is deinitialized, which results in a crash. |
| </p> |
| <p> |
| There is no way for Boost.Log to influence the order of global deinitialization, |
| but the problem can be worked around on the user's side. One solution is |
| to make sure the locale is initialized <span class="emphasis"><em>before</em></span> Boost.Log. |
| This can be achieved by calling <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">filesystem</span><span class="special">::</span><span class="identifier">path</span><span class="special">::</span><span class="identifier">codecvt</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">filesystem</span><span class="special">::</span><span class="identifier">path</span><span class="special">::</span><span class="identifier">imbue</span><span class="special">()</span></code> early during the application startup, before |
| performing any calls to Boost.Log. For example: |
| </p> |
| <pre class="programlisting"><span class="keyword">int</span> <span class="identifier">main</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">argc</span><span class="special">,</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">argv</span><span class="special">[])</span> |
| <span class="special">{</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">filesystem</span><span class="special">::</span><span class="identifier">path</span><span class="special">::</span><span class="identifier">imbue</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">locale</span><span class="special">(</span><span class="string">"C"</span><span class="special">));</span> |
| <span class="identifier">initialize_log</span><span class="special">();</span> |
| |
| <span class="comment">// ...</span> |
| <span class="special">}</span> |
| </pre> |
| <p> |
| Note that in this case you can't use Boost.Log in global constructors or |
| you have to make sure that <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">filesystem</span><span class="special">::</span><span class="identifier">path</span><span class="special">::</span><span class="identifier">imbue</span><span class="special">()</span></code> is still called first. |
| </p> |
| <p> |
| Another solution is to remove and destroy file sinks from the logging core |
| before returning from <code class="computeroutput"><span class="identifier">main</span><span class="special">()</span></code>. This way file rotation will happen before |
| leaving <code class="computeroutput"><span class="identifier">main</span><span class="special">()</span></code>, |
| while the locale is still valid. The file sinks can be removed either individually |
| or as a part of the <code class="computeroutput"><span class="identifier">remove_all_sinks</span><span class="special">()</span></code> call: |
| </p> |
| <pre class="programlisting"><span class="keyword">int</span> <span class="identifier">main</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">argc</span><span class="special">,</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">argv</span><span class="special">[])</span> |
| <span class="special">{</span> |
| <span class="comment">// ...</span> |
| |
| <span class="identifier">logging</span><span class="special">::</span><span class="identifier">core</span><span class="special">::</span><span class="identifier">get</span><span class="special">()-></span><span class="identifier">remove_all_sinks</span><span class="special">();</span> |
| |
| <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> |
| <span class="special">}</span> |
| </pre> |
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| <td align="right"><div class="copyright-footer">Copyright © 2007-2015 Andrey |
| Semashev<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>). |
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