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<th>Priority</th>
<td>medium
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Huge multi-threading violations in cairo"
href="https://bugs.freedesktop.org/show_bug.cgi?id=81874">81874</a>
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<th>Assignee</th>
<td>david@freetype.org
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<th>Summary</th>
<td>Huge multi-threading violations in cairo
</td>
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<th>QA Contact</th>
<td>cairo-bugs@cairographics.org
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<th>Severity</th>
<td>critical
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>OS</th>
<td>All
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<th>Reporter</th>
<td>es20490446e@gmail.com
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<th>Hardware</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
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<th>Version</th>
<td>unspecified
</td>
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<th>Component</th>
<td>freetype font backend
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<th>Product</th>
<td>cairo
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<pre>I looked at the implementation of cairo-ft-font.c and it seems that there are
huge multi-threading violations in cairo. The reason is that FreeType API
documentation clearly states:
In multi-threaded applications, make sure that the same FT_Library object or
any of its children doesn't get accessed in parallel.
Cairo initializes FT_Library for its font map and there's a lock for that,
however it's only used for font map manipulations, the actual FT_ library calls
are completely unprotected with that lock, although they should be! What adds
to the injury is that cairo-ft-font.c even has this comment on one of its
functions:
You must be careful when using this function in a library or in a
threaded application, because freetype's design makes it unsafe to
call freetype functions simultaneously from multiple threads, (even
if using distinct FT_Face objects)</pre>
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