task11.htm

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<h2>
  <a name="1204804"> </a><font color="#003366"  face="Verdana, Arial, Helvetica, sans-serif">5.10 	 Suspending tasks</font>
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<p>
  <a name="1204805"> </a><font size=2  face="Verdana, Arial, Helvetica, sans-serif">Normally a task only deschedules when it is waiting for an event such as a semaphore signal. This requires that the task itself call a function indicating that it is willing to deschedule at that point (for example, by calling <font size=2 face=Courier><strong>semaphore_wait</strong></font>). However, sometimes it is useful to be able to control a task, causing it to forcibly deschedule, without it explicitly indicating that it is willing to be descheduled. This can be done by suspending the task.</font>
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<p>
  <a name="1204806"> </a><font size=2  face="Verdana, Arial, Helvetica, sans-serif">When a task is suspended, it stops executing immediately. When the task starts executing again, another task must resume it. When it is resumed, the task will be unaware that it was suspended, other than the time delay.</font>
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<p>
  <a name="1204807"> </a><font size=2  face="Verdana, Arial, Helvetica, sans-serif">Task suspension is in addition to any other reason that a task is descheduled. Thus a task which is waiting on a semaphore and has been suspended will not start executing again until both the task is resumed and the semaphore is signalled, although these can occur in either order.</font>
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<p>
  <a name="1209108"> </a><font size=2  face="Verdana, Arial, Helvetica, sans-serif"><b>Caution:</b></font>
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<dl><dl>    <dl>
      <dt> <a name="1209112"> </a><font size=2  face="Verdana, Arial, Helvetica, sans-serif">Task suspension can easily cause deadlock; see <a href="libs135.htm#1242681"><font  color="#0000ff" face="Verdana, Arial, Helvetica, sans-serif"><i>task_suspend</i></font></a> in <a href="libs.htm#1214476"><font  color="#0000ff" face="Verdana, Arial, Helvetica, sans-serif"><i>Chapter

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