https://svn.boost.org/trac10/ticket/8595 <p> We had serious performance problem after transfer to boost version 1.53. The reason - bug in processing of "async" parameter of <strong>mapped_region::flush</strong> (windows version). </p> <pre class="wiki"> else if(async &amp;&amp; m_file_or_mapping_hnd != winapi::invalid_handle_value &amp;&amp; winapi::get_file_type(m_file_or_mapping_hnd) == winapi::file_type_disk) { return winapi::flush_file_buffers(m_file_or_mapping_hnd); } </pre><p> So if <strong>async = true</strong> then <strong>flush</strong> function works in synchronous mode. I think the code must be: </p> <pre class="wiki">else if(!async &amp;&amp; .... </pre><p> Sergey Voropaev </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/8595 Trac 1.4.3 Ion Gaztañaga Mon, 20 May 2013 15:35:57 GMT https://svn.boost.org/trac10/ticket/8595#comment:2 https://svn.boost.org/trac10/ticket/8595#comment:2 <ul> <li><strong>status</strong> <span class="trac-field-old">new</span> → <span class="trac-field-new">closed</span> </li> <li><strong>resolution</strong> → <span class="trac-field-new">fixed</span> </li> </ul> <p> (In <a class="changeset" href="https://svn.boost.org/trac10/changeset/84390" title="Fixes #8595">[84390]</a>) Fixes <a class="closed ticket" href="https://svn.boost.org/trac10/ticket/8595" title="#8595: Bugs: mapped_region::flush - invalid interpretation of async parameter (win32) (closed: fixed)">#8595</a> </p> Ticket