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<th colspan="3" align="center">LPRng Reference Manual: 24
Sep 2004 (For LPRng-3.8.28)</th>
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<h1 class="SECT1"><a name="SPOOLQ">15.4. Spool Queue
Processing</a></h1>
<p>Options used:</p>
<ul>
<li>
<p><var class="LITERAL">lpd_force_poll=</var><span class=
"emphasis"><i class="EMPHASIS">Force <b class=
"APPLICATION">lpd</b> to periodically poll print
queues</i></span></p>
</li>
<li>
<p><var class="LITERAL">lpd_poll_time=</var><span class=
"emphasis"><i class="EMPHASIS">Time between
polls</i></span></p>
</li>
<li>
<p><var class="LITERAL">max_servers_active=</var><span
class="emphasis"><i class="EMPHASIS">Maximum number of
active servers</i></span></p>
</li>
</ul>
<br>
<br>
<p>When the <b class="APPLICATION">lpd</b> server starts, it
will fork a set of subserver processes, each which will
handle an individual queue.</p>
<p>If a system has a large number of queues, then this
forking operation may result in the <b class=
"APPLICATION">lpd</b> server exhausting the process
resources. To control this, the <var class=
"LITERAL">max_servers_active</var> value restricts the number
of active children to the specified value. If this value is
0, then 50% of the maximum system processes value will be
used.</p>
<p>Due to the limits on the number of processes, there may be
times when a job is placed in a queue, but the <b class=
"APPLICATION">lpd</b> server is unable to start handling the
job. When all of the children of the main <b class=
"APPLICATION">lpd</b> server have exited, the server starts a
timer. After <var class="LITERAL">lpd_poll_time</var>
seconds, it will scan the queues, looking for jobs to
process, and starts a process to service them. If it does not
find any jobs it remains idle.</p>
<p>The <var class="LITERAL">lpd_force_poll</var> flag causes
the server to periodically poll the queues. This is useful
when there is a high possibility that jobs could fail to be
printed due to high loads on the server.</p>
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