Fix race condition in nextInsertBatch() causing off-by-1 doc count

has_next_create() and next() were separate non-atomic operations, allowing
two threads to both pass the boundary check at create_e and produce one
extra document beyond the intended range.

Fix: atomically claim the index with getAndIncrement() first, then break
if the claimed index is out of bounds — eliminating the check-then-act gap.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ShivamPaliwal1

src/main/java/utils/docgen/DocumentGenerator.java

@@ -464,8 +464,22 @@ public Tuple2<String, Object> nextExpiry() {
     public List<Tuple2<String, Object>> nextInsertBatch() {
         List<Tuple2<String, Object>> docs = new ArrayList<Tuple2<String,Object>>();
         int count = 0;
-        while (this.has_next_create() && count<ws.batchSize*ws.creates/100) {
-            docs.add(this.next());
+        while (count < ws.batchSize * ws.creates / 100) {
+            long idx = this.ws.dr.createItr.getAndIncrement();
+            if (idx >= this.ws.dr.create_e) break;
+            String k = null;
+            Object v = null;
+            try {
+                if (this.target_vbuckets != null && this.target_vbuckets.length > 0) {
+                    k = this.generated_create_keys.get(idx);
+                } else {
+                    k = (String) this.keyMethod.invoke(this.keys, idx);
+                }
+                v = (Object) this.valMethod.invoke(this.vals, k);
+            } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e1) {
+                e1.printStackTrace();
+            }
+            docs.add(Tuples.of(k, v));
             count += 1;
         }
         return docs;