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...if not running in direct mode. Previous versions could run without any active workers. This simplifies the code at a very small expense. See v5 compatibility note document for more in-depth discussion.
31 lines
1.9 KiB
HTML
31 lines
1.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html><head><title>Compatibility notes for rsyslog v5</title>
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</head>
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<body>
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<h1>Compatibility Notes for rsyslog v5</h1>
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<p><small><i>Written by <a href="http://www.gerhards.net/rainer">Rainer Gerhards</a>
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(2009-07-15)</i></small></p>
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<p>The changes introduced in rsyslog v5 are numerous, but not very intrusive.
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This document describes things to keep in mind when moving from v4 to v5. It
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does not list enhancements nor does it talk about compatibility concerns introduced
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by earlier versions (for this, see their respective compatibility documents).
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<h2>HUP processing</h2>
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<p>The $HUPisRestart directive is supported by some early v5 versions, but has been removed
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in 5.1.3 and above. That means that restart-type HUP processing is no longer
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available. This processing was redundant and had a lot a drawbacks.
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For details, please see the
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<a href="v4compatibility.html">rsyslog v4 compatibility notes</a> which elaborate
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on the reasons and the (few) things you may need to change.
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<h2>Queue Worker Thread Shutdown</h2>
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<p>Previous rsyslog versions had the capability to "run" on zero queue worker
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if no work was required. This was done to save a very limited number of resources. However,
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it came at the price of great complexity. In v5, we have decided to let a minium of one
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worker run all the time. The additional resource consumption is probably not noticable at
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all, however, this enabled us to do some important code cleanups, resulting in faster
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and more reliable code (complex code is hard to maintain and error-prone). From the
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regular user's point of view, this change should be barely noticable. I am including the
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note for expert users, who will notice it in rsyslog debug output and other analysis tools.
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So it is no error if each queue in non-direct mode now always runs at least one worker
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thread.
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</body></html>
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