SOLR-10226 JMX metric avgTimePerRequest broken.

solr/CHANGES.txt

@@ -96,6 +96,10 @@ Detailed Change List
 
 Upgrade Notes
 ----------------------
+* SOLR-10226: JMX metric "avgTimePerRequest" (and the corresponding metric in the metrics API for
+  each handler) used to be a simple non-decaying average based on total cumulative time and the
+  number of requests. New Codahale Metrics implementation applies exponential decay to this value,
+  which heavily biases the average towards the last 5 minutes. (ab)
 
 New Features
 ----------------------
@@ -212,6 +216,8 @@ Bug Fixes
 
 * SOLR-10088: Installer script does not put zoo.cfg in SOLR_HOME (janhoy)
 
+* SOLR-10226: add back "totalTime" metric to all handlers. See also the back-compat note. (ab)
+
 Optimizations
 ----------------------
 

solr/core/src/java/org/apache/solr/handler/RequestHandlerBase.java

@@ -66,6 +66,7 @@ public abstract class RequestHandlerBase implements SolrRequestHandler, SolrInfo
   private Meter numTimeouts = new Meter();
   private Counter requests = new Counter();
   private Timer requestTimes = new Timer();
+  private Counter totalTime = new Counter();
 
   private final long handlerStart;
 
@@ -143,6 +144,7 @@ public abstract class RequestHandlerBase implements SolrRequestHandler, SolrInfo
     numTimeouts = manager.meter(registryName, "timeouts", getCategory().toString(), scope);
     requests = manager.counter(registryName, "requests", getCategory().toString(), scope);
     requestTimes = manager.timer(registryName, "requestTimes", getCategory().toString(), scope);
+    totalTime = manager.counter(registryName, "totalTime", getCategory().toString(), scope);
   }
 
   public static SolrParams getSolrParamsFromNamedList(NamedList args, String key) {
@@ -209,7 +211,8 @@ public abstract class RequestHandlerBase implements SolrRequestHandler, SolrInfo
         }
       }
     } finally {
-      timer.stop();
+      long elapsed = timer.stop();
+      totalTime.inc(elapsed);
     }
   }
 
@@ -292,6 +295,8 @@ public abstract class RequestHandlerBase implements SolrRequestHandler, SolrInfo
     lst.add("serverErrors", numServerErrors.getCount());
     lst.add("clientErrors", numClientErrors.getCount());
     lst.add("timeouts", numTimeouts.getCount());
+    // convert totalTime to ms
+    lst.add("totalTime", MetricUtils.nsToMs(totalTime.getCount()));
     MetricUtils.addMetrics(lst, requestTimes);
     return lst;
   }

solr/core/src/java/org/apache/solr/util/stats/MetricUtils.java

@@ -63,7 +63,7 @@ public class MetricUtils {
    * @param ns the amount of time in nanoseconds
    * @return the amount of time in milliseconds
    */
-  static double nsToMs(double ns) {
+  public static double nsToMs(double ns) {
     return ns / TimeUnit.MILLISECONDS.toNanos(1);
   }