An option to coarsen flame graphs (async-profiler#1018)

SAP · Oct 10, 2024 · 061f03d · 061f03d
1 parent 37ff942
commit 061f03d
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Showing 4 changed files with 31 additions and 0 deletions.
diff --git a/src/converter/Main.java b/src/converter/Main.java
@@ -113,6 +113,7 @@ private static void usage() {
                 "Flame Graph options:\n" +
                 "     --title STRING     Flame Graph title\n" +
                 "     --minwidth X       Skip frames smaller than X%\n" +
+                "     --grain X          Coarsen Flame Graph to the given grain size\n" +
                 "     --skip N           Skip N bottom frames\n" +
                 "  -r --reverse          Reverse stack traces (icicle graph)\n" +
                 "  -I --include REGEX    Include only stacks with the specified frames\n" +

diff --git a/src/converter/one/convert/Arguments.java b/src/converter/one/convert/Arguments.java
@@ -18,6 +18,7 @@ public class Arguments {
     public Pattern include;
     public Pattern exclude;
     public double minwidth;
+    public double grain;
     public int skip;
     public boolean help;
     public boolean reverse;

diff --git a/src/converter/one/convert/JfrConverter.java b/src/converter/one/convert/JfrConverter.java
@@ -70,6 +70,10 @@ protected EventAggregator collectEvents() throws IOException {
             }
         }
 
+        if (args.grain > 0) {
+            agg.coarsen(args.grain);
+        }
+
         return agg;
     }
 

diff --git a/src/converter/one/jfr/event/EventAggregator.java b/src/converter/one/jfr/event/EventAggregator.java
@@ -15,6 +15,7 @@ public class EventAggregator {
     private long[] samples;
     private long[] values;
     private int size;
+    private double fraction;
 
     public EventAggregator(boolean threads, boolean total, double factor) {
         this.threads = threads;
@@ -67,6 +68,30 @@ public void forEach(ValueVisitor visitor) {
         }
     }
 
+    public void coarsen(double grain) {
+        for (int i = 0; i < keys.length; i++) {
+            if (keys[i] != null) {
+                long s0 = samples[i];
+                long s1 = round(s0 / grain);
+                if (s1 == 0) {
+                    keys[i] = null;
+                    size--;
+                }
+                samples[i] = s1;
+                values[i] = (long) (values[i] * ((double) s1 / s0));
+            }
+        }
+    }
+
+    private long round(double d) {
+        long r = (long) d;
+        if ((fraction += d - r) >= 1.0) {
+            fraction -= 1.0;
+            r++;
+        }
+        return r;
+    }
+
     private int hashCode(Event e) {
         return e.hashCode() + (threads ? e.tid * 31 : 0);
     }