Perf between PersistentSkipListMap vs PersistentSkipListMap2

[JerryYangSH]

I tested the latency PersistentSkipListMap and PersistentSkipListMap2. It looks PersistentSkipListMap is doing a better job than PersistentSkipListMap2 regarding the avg latency. What makes this difference? Which one is preferred?

Testing benchmark PersistentSkipListMap******
[Key Count 1000] avg lat:
DELETE : 151 (us)
CREATE : 158 (us)
GET : 74 (us)
UPDATE : 120 (us)
[Key Count 10000] avg lat:
DELETE : 71 (us)
CREATE : 130 (us)
GET : 143 (us)
UPDATE : 82 (us)
[Key Count 50000] avg lat:
DELETE : 102 (us)
CREATE : 117 (us)
GET : 45 (us)
UPDATE : 126 (us)
Testing benchmark PersistentSkipListMap2******
[Key Count 1000] avg lat:
DELETE : 201 (us)
CREATE : 214 (us)
GET : 64 (us)
UPDATE : 152 (us)
[Key Count 10000] avg lat:
DELETE : 122 (us)
CREATE : 198 (us)
GET : 68 (us)
UPDATE : 163 (us)
My Test code is below:

jerry@u19:~/opensources/pcj$ git diff
diff --git a/src/test/java/tests/PersistentSkipListMapTest.java b/src/test/java/tests/PersistentSkipListMapTest.java
index cfdbc4d..1782295 100644
--- a/src/test/java/tests/PersistentSkipListMapTest.java
+++ b/src/test/java/tests/PersistentSkipListMapTest.java
@@ -43,6 +43,8 @@ static boolean verbose = false;
         System.out.println("****************PersistentSkipListMap Tests************");
         return testInsertion() &&
         testRemoval() &&
+        testBenchmark(getPersistentSkipListMap()) &&
+        testBenchmark(getPersistentSkipListMap2()) &&
         testIteration() &&
         testSubMap() &&
         testPutAll() &&
@@ -64,6 +66,26 @@ static boolean verbose = false;
                return map;
        }

+    private static PersistentSkipListMap<PersistentString, PersistentString> getPersistentSkipListMap() {
+        String id = threadSafeId("tests.PersistentSkipListMap");
+        PersistentSkipListMap<PersistentString, PersistentString> map = ObjectDirectory.get(id,PersistentSkipListMap.class);
+        if(map == null) {
+            map = new PersistentSkipListMap<>();
+            ObjectDirectory.put(id, map);
+        }
+        return map;
+    }
+
+    private static PersistentSkipListMap2<PersistentString, PersistentString> getPersistentSkipListMap2() {
+        String id = threadSafeId("tests.PersistentSkipListMap2");
+        PersistentSkipListMap2<PersistentString, PersistentString> map = ObjectDirectory.get(id,PersistentSkipListMap2.class);
+        if(map == null) {
+            map = new PersistentSkipListMap2<>();
+            ObjectDirectory.put(id, map);
+        }
+        return map;
+    }
+
     @SuppressWarnings("unchecked")
     public static boolean testInsertion() {
         if (verbose) System.out.println("****************Testing insertion**********************");
@@ -93,6 +115,82 @@ static boolean verbose = false;
         return true;
     }

+    @SuppressWarnings("unchecked")
+    public static boolean testBenchmark(PersistentSortedMap<PersistentString, PersistentString> map) {
+        System.out.println(String.format("****************Testing benchmark %s**********************", map.getClass().getSimpleName()));
+
+        assert (map != null);
+        map.clear();
+        assert(map.size() == 0);
+
+        final int KeySize = 128;
+        final int ValueSize = 1024;
+        StringBuilder keyPrefixBuilder = new StringBuilder();
+        for (int i = 0; i < KeySize; i++) {
+            keyPrefixBuilder.append('~');
+        }
+        String keyPrefix = keyPrefixBuilder.toString();
+        StringBuilder valuePrefixBuilder = new StringBuilder();
+        for (int i = 0; i < ValueSize; i++) {
+            valuePrefixBuilder.append('&');
+        }
+        String valuePrefix = valuePrefixBuilder.toString();
+
+        final int[] LoopCounts = new int[] {1000, 10000, 50000};
+        for (int LoopCount : LoopCounts) {
+            System.out.println(String.format("[Key Count %6d] avg lat:", LoopCount));
+            map.clear();
+            assert(map.size() == 0);
+            Map<String, Long> latencies = new HashMap<>();
+
+            // CREATE:
+            long start = System.nanoTime();
+            for (int l = 0; l < LoopCount; l++) {
+                PersistentString key = new PersistentString(keyPrefix + l);
+                PersistentString val = new PersistentString(valuePrefix + l);
+                PersistentString out = map.put(key, val);
+                if (out != null) {
+                    System.out.println(String.format("CREATING key %s failed, out = %s", keyPrefix + l, out.toString()));
+                }
+                assert(out == null);
+            }
+            latencies.put("CREATE", (System.nanoTime() - start) / LoopCount);
+
+            // GET
+            start = System.nanoTime();
+            for (int l = 0; l < LoopCount; l++) {
+                PersistentString key = new PersistentString(keyPrefix + l);
+                assert(map.get(key).toString().equals(valuePrefix + l));
+            }
+            latencies.put("GET", (System.nanoTime() - start) / LoopCount);
+
+            // UPDATE
+            start = System.nanoTime();
+            for (int l = 0; l < LoopCount; l++) {
+                PersistentString key = new PersistentString(keyPrefix + l);
+                PersistentString val = new PersistentString(valuePrefix);
+                PersistentString out = map.put(key, val);
+                assert(out.toString().equals(valuePrefix + l));
+            }
+            latencies.put("UPDATE", (System.nanoTime() - start) / LoopCount);
+
+            // DELETE
+            start = System.nanoTime();
+            for (int l = 0; l < LoopCount; l++) {
+                PersistentString key = new PersistentString(keyPrefix + l);
+                PersistentString out = map.remove(key);
+            }
+            latencies.put("DELETE", (System.nanoTime() - start) / LoopCount);
+
+            for (Map.Entry<String, Long> lat : latencies.entrySet()) {
+                System.out.println(String.format("\t%8s : %8d (us)", lat.getKey(), lat.getValue() / 1000));
+            }
+        }
+
+        map.clear();
+        return true;
+    }