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From ma...@apache.org
Subject svn commit: r1528176 - in /tomcat/tc7.0.x/trunk: ./ java/org/apache/tomcat/util/net/AprEndpoint.java
Date Tue, 01 Oct 2013 18:43:04 GMT
Author: markt
Date: Tue Oct  1 18:43:04 2013
New Revision: 1528176

URL: http://svn.apache.org/r1528176
Log:
Address issue reported with high CPU usage under low load load.

Modified:
    tomcat/tc7.0.x/trunk/   (props changed)
    tomcat/tc7.0.x/trunk/java/org/apache/tomcat/util/net/AprEndpoint.java

Propchange: tomcat/tc7.0.x/trunk/
------------------------------------------------------------------------------
  Merged /tomcat/trunk:r1528171

Modified: tomcat/tc7.0.x/trunk/java/org/apache/tomcat/util/net/AprEndpoint.java
URL: http://svn.apache.org/viewvc/tomcat/tc7.0.x/trunk/java/org/apache/tomcat/util/net/AprEndpoint.java?rev=1528176&r1=1528175&r2=1528176&view=diff
==============================================================================
--- tomcat/tc7.0.x/trunk/java/org/apache/tomcat/util/net/AprEndpoint.java (original)
+++ tomcat/tc7.0.x/trunk/java/org/apache/tomcat/util/net/AprEndpoint.java Tue Oct  1 18:43:04
2013
@@ -1274,6 +1274,13 @@ public class AprEndpoint extends Abstrac
         protected int pollerTime;
 
         /**
+         * Variable poller timeout that adjusts depending on how many poll sets
+         * are in use so that the total poll time across all poll sets remains
+         * equal to pollTime.
+         */
+        private int nextPollerTime;
+
+        /**
          * Root pool.
          */
         protected long pool = 0;
@@ -1361,6 +1368,7 @@ public class AprEndpoint extends Abstrac
 
             pollerCount = defaultPollerSize / actualPollerSize;
             pollerTime = pollTime / pollerCount;
+            nextPollerTime = pollerTime;
 
             pollers = new long[pollerCount];
             pollers[0] = pollset;
@@ -1735,7 +1743,18 @@ public class AprEndpoint extends Abstrac
                         int rv = 0;
                         // Iterate on each pollers, but no need to poll empty pollers
                         if (pollerSpace[i] < actualPollerSize) {
-                            rv = Poll.poll(pollers[i], pollerTime, desc, true);
+                            rv = Poll.poll(pollers[i], nextPollerTime, desc, true);
+                            // Reset the nextPollerTime
+                            nextPollerTime = pollerTime;
+                        } else {
+                            // Skipping an empty poll set means skipping a wait
+                            // time of pollerTime microseconds. If most of the
+                            // poll sets are skipped then this loop will be
+                            // tighter than expected which could lead to higher
+                            // than expected CPU usage. Extending the
+                            // nextPollerTime ensures that this loop always
+                            // takes about the same time to execute.
+                            nextPollerTime += pollerTime;
                         }
                         if (rv > 0) {
                             pollerSpace[i] += rv;



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