Since only a simple single decimal floatingpoint number is needed avoid using string and floating point formatting. Use a simpler variant you get a 15 X speedup of this frequently called code.

2 files changed, 53 insertions, 5 deletions

diff --git a/config-provisioning/src/main/java/com/yahoo/config/provision/NodeResources.java b/config-provisioning/src/main/java/com/yahoo/config/provision/NodeResources.java
index 9cae0a08360..e5c2bf658ab 100644
--- a/config-provisioning/src/main/java/com/yahoo/config/provision/NodeResources.java
+++ b/config-provisioning/src/main/java/com/yahoo/config/provision/NodeResources.java
@@ -1,6 +1,9 @@
 // Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.config.provision;
 
+import java.text.DecimalFormat;
+import java.text.FieldPosition;
+import java.text.NumberFormat;
 import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
@@ -215,13 +218,32 @@ public class NodeResources {
         return Objects.hash(vcpu, memoryGb, diskGb, bandwidthGbps, diskSpeed, storageType);
     }
 
+    private static StringBuffer appendDouble(StringBuffer sb, double d) {
+        sb.append((long)d).append('.').append(Math.round(d*10)%10);
+        return sb;
+    }
     @Override
     public String toString() {
-        return String.format(Locale.ENGLISH, "[vcpu: %1$.1f, memory: %2$.1f Gb, disk %3$.1f Gb" +
-                            (bandwidthGbps > 0 ? ", bandwidth: %4$.1f Gbps" : "") +
-                            ( ! diskSpeed.isDefault() ? ", disk speed: " + diskSpeed : "") +
-                            ( ! storageType.isDefault() ? ", storage type: " + storageType : "") + "]",
-                            vcpu, memoryGb, diskGb, bandwidthGbps);
+        StringBuffer sb = new StringBuffer("[vcpu: ");
+        appendDouble(sb, vcpu);
+        sb.append(", memory: ");
+        appendDouble(sb, memoryGb);
+        sb.append(" Gb, disk ");
+        appendDouble(sb, diskGb);
+        sb.append(" Gb");
+        if (bandwidthGbps > 0) {
+            sb.append(", bandwidth: ");
+            appendDouble(sb, bandwidthGbps);
+            sb.append(" Gbps");
+        }
+        if ( !diskSpeed.isDefault()) {
+            sb.append(", disk speed: ").append(diskSpeed);
+        }
+        if ( !storageType.isDefault()) {
+            sb.append(", storage type: ").append(storageType);
+        }
+        sb.append(']');
+        return sb.toString();
     }
 
     /** Returns true if all the resources of this are the same or larger than the given resources */
diff --git a/config-provisioning/src/test/java/com/yahoo/config/provision/NodeResourcesTest.java b/config-provisioning/src/test/java/com/yahoo/config/provision/NodeResourcesTest.java
index 21e1afeed17..8d39691a3bb 100644
--- a/config-provisioning/src/test/java/com/yahoo/config/provision/NodeResourcesTest.java
+++ b/config-provisioning/src/test/java/com/yahoo/config/provision/NodeResourcesTest.java
@@ -16,6 +16,32 @@ public class NodeResourcesTest {
                      new NodeResources(1., 10., 100., 0).toString());
         assertEquals("[vcpu: 0.3, memory: 3.3 Gb, disk 33.3 Gb, bandwidth: 0.3 Gbps]",
                      new NodeResources(1/3., 10/3., 100/3., 0.3).toString());
+        assertEquals("[vcpu: 0.7, memory: 6.7 Gb, disk 66.7 Gb, bandwidth: 0.7 Gbps]",
+                new NodeResources(2/3., 20/3., 200/3., 0.67).toString());
+    }
+
+    private long runTest(NodeResources [] resouces, int num) {
+        long sum = 0;
+        for (int i = 0; i < num; i++) {
+            for (NodeResources ns :resouces) {
+                sum += ns.toString().length();
+            }
+        }
+        return sum;
+    }
+    @Test
+    public void benchmark() {
+        NodeResources [] resouces = new NodeResources[100];
+        for (int i = 0; i < resouces.length; i++) {
+            resouces[i] = new NodeResources(1/3., 10/3., 100/3., 0.3);
+        }
+        int NUM_ITER = 100; // Use at least 100000 for proper benchmarking
+        long warmup = runTest(resouces, NUM_ITER);
+        long start = System.nanoTime();
+        long benchmark = runTest(resouces, NUM_ITER);
+        long duration = System.nanoTime() - start;
+        System.out.println("NodeResources.toString() took " + duration/1000000 + " ms");
+        assertEquals(warmup, benchmark);
     }
 
 }