diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java
index 867c5e3..cf69bfe 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java
@@ -15,10 +15,13 @@
 
 package edu.uci.ics.asterix.common.context;
 
+import java.util.List;
+
 import edu.uci.ics.asterix.common.api.IAsterixAppRuntimeContext;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndex;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
@@ -36,8 +39,8 @@
 
     @Override
     public void diskComponentAdded(final ILSMIndex index) throws HyracksDataException, IndexException {
-        int totalNumDiskComponents = index.getImmutableComponents().size();
-        if (!ctx.isShuttingdown() && totalNumDiskComponents >= threshold) {
+        List<ILSMComponent> immutableComponents = index.getImmutableComponents();
+        if (!ctx.isShuttingdown() && immutableComponents.size() >= threshold) {
             ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
                     NoOpOperationCallback.INSTANCE);
             accessor.scheduleMerge(NoOpIOOperationCallback.INSTANCE);
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/DatasetLifecycleManager.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/DatasetLifecycleManager.java
index 17ad331..ded7237 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/DatasetLifecycleManager.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/DatasetLifecycleManager.java
@@ -270,7 +270,7 @@
                 for (int i = 0; i < NUM_MUTABLE_BUFFERS; i++) {
                     MultitenantVirtualBufferCache vbc = new MultitenantVirtualBufferCache(new VirtualBufferCache(
                             new HeapBufferAllocator(), storageProperties.getMemoryComponentPageSize(),
-                            storageProperties.getMemoryComponentNumPages() / NUM_MUTABLE_BUFFERS));
+                            datasetID < 100? storageProperties.getMemoryComponentNumPages(): 4 / NUM_MUTABLE_BUFFERS));
                     vbcs.add(vbc);
                 }
                 datasetVirtualBufferCaches.put(datasetID, vbcs);
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 b83fe8a..c13cd42 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
@@ -81,11 +81,14 @@
                 break;
             }
         }
-        if (needsFlush && numActiveOperations.get() == 0) {
-            for (ILSMIndex lsmIndex : indexes) {
-                ILSMIndexAccessor accessor = (ILSMIndexAccessor) lsmIndex.createAccessor(
-                        NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-                accessor.scheduleFlush(((BaseOperationTracker) lsmIndex.getOperationTracker()).getIOOperationCallback());
+        synchronized (this) {
+            if (needsFlush && numActiveOperations.get() == 0) {
+                for (ILSMIndex lsmIndex : indexes) {
+                    ILSMIndexAccessor accessor = (ILSMIndexAccessor) lsmIndex.createAccessor(
+                            NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+                    accessor.scheduleFlush(((BaseOperationTracker) lsmIndex.getOperationTracker())
+                            .getIOOperationCallback());
+                }
             }
         }
     }