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<title>5.6.6 Working with threads
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<H2><A NAME=
"SECTION007660000000000000000"></A><A NAME=
"decimal-threads"></A>
5.6.6 Working with threads
The
<tt class=
"function">getcontext()
</tt> function accesses a different
<tt class=
"class">Context
</tt>
object for each thread. Having separate thread contexts means that threads
may make changes (such as
<code>getcontext.prec=
10</code>) without interfering with
Likewise, the
<tt class=
"function">setcontext()
</tt> function automatically assigns its target
If
<tt class=
"function">setcontext()
</tt> has not been called before
<tt class=
"function">getcontext()
</tt>,
then
<tt class=
"function">getcontext()
</tt> will automatically create a new context for use
The new context is copied from a prototype context called
<var>DefaultContext
</var>. To control the defaults so that each thread will use the
same values throughout the application, directly modify the
<var>DefaultContext
</var> object. This should be done
<em>before
</em> any threads are
started so that there won't be a race condition between threads calling
<tt class=
"function">getcontext()
</tt>. For example:
<div class=
"verbatim"><pre>
# Set applicationwide defaults for all threads about to be launched
DefaultContext.rounding = ROUND_DOWN
DefaultContext.traps = ExtendedContext.traps.copy()
DefaultContext.traps[InvalidOperation] =
1
setcontext(DefaultContext)
# Afterwards, the threads can be started
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<span class=
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2005.
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