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<title>Issue 1151: Behavior of the library in the presence of threads is incompletely specified</title>
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<p><em>This page is a snapshot from the LWG issues list, see the <a href="lwg-active.html">Library Active Issues List</a> for more information and the meaning of <a href="lwg-active.html#Resolved">Resolved</a> status.</em></p>
<h3 id="1151"><a href="lwg-defects.html#1151">1151</a>. Behavior of the library in the presence of threads is incompletely specified</h3>
<p><b>Section:</b> 16 <a href="https://wg21.link/library">[library]</a> <b>Status:</b> <a href="lwg-active.html#Resolved">Resolved</a>
 <b>Submitter:</b> LWG <b>Opened:</b> 2009-06-28 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View other</b> <a href="lwg-index-open.html#library">active issues</a> in [library].</p>
<p><b>View all other</b> <a href="lwg-index.html#library">issues</a> in [library].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#Resolved">Resolved</a> status.</p>
<p><b>Discussion:</b></p>
<p><b>Addresses US 63</b></p>

   <p><b>Description</b></p>
        <p>The behavior of the library in the presence of threads
        is incompletely specified.</p>
        <p>For example, if thread 1 assigns to <code>X</code>, then writes data
        to file <code>f</code>, which is read by thread 2, and then accesses
        variable <code>X</code>, is thread 2 guaranteed to be able to see the
        value assigned to <code>X</code> by thread 1? In other words, does the
        write of the data "happen before" the read?</p>
        <p>Another example: does simultaneous access using <code>operator
        at()</code> to different characters in the same non-const string
        really introduce a data race?</p>
<p><b>Suggestion</b></p>
<p><b>Notes</b></p><p>17 SG: should go to threads group; misclassified in document
</p>

    <p>Concurrency SG: Create an issue. Hans will look into it.</p>

<p><i>[
2009 Santa Cruz:
]</i></p>


<blockquote><p>
Move to "Open". Hans and the rest of the concurrency working group will
study this. We can't make progress without a thorough review and a
paper.
</p></blockquote>

<p><i>[
2010 Pittsburgh:  Moved to NAD Editorial.  Rationale added below.
]</i></p>




<p><b>Rationale:</b></p>
<p>
Solved by
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3069.html">N3069</a>.
</p>


<p id="res-1151"><b>Proposed resolution:</b></p>





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