diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java
index 0211d6c..ad363f3 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java
@@ -16,7 +16,6 @@
 package edu.uci.ics.asterix.common.context;
 
 import java.util.Set;
-import java.util.concurrent.atomic.AtomicInteger;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
@@ -34,21 +33,22 @@
     private final IVirtualBufferCache datasetBufferCache;
     private final int datasetID;
     // Number of active operations on a ILSMIndex instance.
-    private AtomicInteger numActiveOperations;
+    private int numActiveOperations;
 
     public PrimaryIndexOperationTracker(DatasetLifecycleManager datasetLifecycleManager, int datasetID,
             ILSMIOOperationCallbackFactory ioOpCallbackFactory) {
         super(ioOpCallbackFactory);
         this.datasetLifecycleManager = datasetLifecycleManager;
-        this.numActiveOperations = new AtomicInteger(0);
+        this.numActiveOperations = 0;
         this.datasetID = datasetID;
         datasetBufferCache = datasetLifecycleManager.getVirtualBufferCache(datasetID);
     }
 
     @Override
-    public void beforeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
-            IModificationOperationCallback modificationCallback) throws HyracksDataException {
-        numActiveOperations.incrementAndGet();
+    public synchronized void beforeOperation(ILSMIndex index, LSMOperationType opType,
+            ISearchOperationCallback searchCallback, IModificationOperationCallback modificationCallback)
+            throws HyracksDataException {
+        numActiveOperations++;
     }
 
     @Override
@@ -64,8 +64,10 @@
     @Override
     public void completeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
             IModificationOperationCallback modificationCallback) throws HyracksDataException {
-        int nActiveOps = numActiveOperations.decrementAndGet();
-
+        int nActiveOps;
+        synchronized (this) {
+            nActiveOps = numActiveOperations--;
+        }
         if (opType != LSMOperationType.FLUSH) {
             flushIfFull(nActiveOps);
         }
@@ -74,6 +76,11 @@
     private void flushIfFull(int nActiveOps) throws HyracksDataException {
         // If we need a flush, and this is the last completing operation, then schedule the flush.
         if (datasetBufferCache.isFull() && nActiveOps == 0) {
+            synchronized (this) {
+                if (numActiveOperations > 0) {
+                    return;
+                }
+            }
             Set<ILSMIndex> indexes = datasetLifecycleManager.getDatasetIndexes(datasetID);
             for (ILSMIndex lsmIndex : indexes) {
                 ILSMIndexAccessor accessor = (ILSMIndexAccessor) lsmIndex.createAccessor(
@@ -85,11 +92,13 @@
     }
 
     public void exclusiveJobCommitted() throws HyracksDataException {
-        numActiveOperations.set(0);
+        synchronized (this) {
+            numActiveOperations = 0;
+        }
         flushIfFull(0);
     }
 
-    public int getNumActiveOperations() {
-        return numActiveOperations.get();
+    public synchronized int getNumActiveOperations() {
+        return numActiveOperations;
     }
 }