Changed config.percentThreshold to also accept a list of percentiles.

The percentThreshold config parameter can now accept a single value or a list of values. A statistic for each percentile threshold will be generated analogous to how the single-value threshold stats were generated before. Updated documentation and example config file as well.
rongyj · Mar 7, 2012 · dd789c7 · dd789c7
1 parent 2377c9b
commit dd789c7
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Showing 3 changed files with 36 additions and 17 deletions.
diff --git a/README.md b/README.md
@@ -33,6 +33,13 @@ Timing
 
 The glork took 320ms to complete this time. StatsD figures out 90th percentile, average (mean), lower and upper bounds for the flush interval.  The percentile threshold can be tweaked with `config.percentThreshold`.
 
+The percentile threshold can be a single value, or a list of values, and will generate the following list of stats for each threshold:
+
+    stats.timers.$KEY.mean_$PCT
+    stats.timers.$KEY.upper_$PCT
+
+Where `$KEY` is the key you stats key you specify when sending to statsd, and `$PCT` is the percentile threshold.
+
 Sampling
 --------
 

diff --git a/exampleConfig.js b/exampleConfig.js
@@ -21,7 +21,8 @@ Optional Variables:
   debugInterval:    interval to print debug information [ms, default: 10000]
   dumpMessages:     log all incoming messages
   flushInterval:    interval (in ms) to flush to Graphite
-  percentThreshold: for time information, calculate the Nth percentile
+  percentThreshold: for time information, calculate the Nth percentile(s)
+                    (can be a single value or list of floating-point values)
                     [%, default: 90]
   keyFlush:         log the most frequently sent keys [object, default: undefined]
     interval:       how often to log frequent keys [ms, default: 0]

diff --git a/stats.js b/stats.js
@@ -165,6 +165,11 @@ config.configFile(process.argv[2], function (config, oldConfig) {
 
     var flushInterval = Number(config.flushInterval || 10000);
 
+    var pctThreshold = config.percentThreshold || 90;
+    if (!Array.isArray(pctThreshold)) {
+      pctThreshold = [ pctThreshold ]; // listify percentiles so single values work the same
+    }
+
     flushInt = setInterval(function () {
       var statString = '';
       var ts = Math.round(new Date().getTime() / 1000);
@@ -184,7 +189,6 @@ config.configFile(process.argv[2], function (config, oldConfig) {
 
       for (key in timers) {
         if (timers[key].length > 0) {
-          var pctThreshold = config.percentThreshold || 90;
           var values = timers[key].sort(function (a,b) { return a-b; });
           var count = values.length;
           var min = values[0];
@@ -193,28 +197,35 @@ config.configFile(process.argv[2], function (config, oldConfig) {
           var mean = min;
           var maxAtThreshold = max;
 
-          if (count > 1) {
-            var thresholdIndex = Math.round(((100 - pctThreshold) / 100) * count);
-            var numInThreshold = count - thresholdIndex;
-            values = values.slice(0, numInThreshold);
-            maxAtThreshold = values[numInThreshold - 1];
+          var message = "";
+
+          var key2;
 
-            // average the remaining timings
-            var sum = 0;
-            for (var i = 0; i < numInThreshold; i++) {
-              sum += values[i];
+          for (key2 in pctThreshold) {
+            var pct = pctThreshold[key2];
+            if (count > 1) {
+              var thresholdIndex = Math.round(((100 - pct) / 100) * count);
+              var numInThreshold = count - thresholdIndex;
+              var pctValues = values.slice(0, numInThreshold);
+              maxAtThreshold = pctValues[numInThreshold - 1];
+
+              // average the remaining timings
+              var sum = 0;
+              for (var i = 0; i < numInThreshold; i++) {
+                sum += pctValues[i];
+              }
+
+              mean = sum / numInThreshold;
             }
 
-            mean = sum / numInThreshold;
+            message += 'stats.timers.' + key + '.mean_'  + pct + ' ' + mean           + ' ' + ts + "\n";
+            message += 'stats.timers.' + key + '.upper_' + pct + ' ' + maxAtThreshold + ' ' + ts + "\n";
           }
 
           timers[key] = [];
 
-          var message = "";
-          message += 'stats.timers.' + key + '.mean ' + mean + ' ' + ts + "\n";
-          message += 'stats.timers.' + key + '.upper ' + max + ' ' + ts + "\n";
-          message += 'stats.timers.' + key + '.upper_' + pctThreshold + ' ' + maxAtThreshold + ' ' + ts + "\n";
-          message += 'stats.timers.' + key + '.lower ' + min + ' ' + ts + "\n";
+          message += 'stats.timers.' + key + '.upper ' + max   + ' ' + ts + "\n";
+          message += 'stats.timers.' + key + '.lower ' + min   + ' ' + ts + "\n";
           message += 'stats.timers.' + key + '.count ' + count + ' ' + ts + "\n";
           statString += message;