Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStoreService.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStoreService.java	(revision 1652009)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentNodeStoreService.java	(working copy)
@@ -125,7 +125,7 @@
 
     private SegmentStore store;
 
-    private SegmentNodeStore delegate;
+    private volatile SegmentNodeStore delegate;
 
     private ObserverTracker observerTracker;
 
@@ -145,7 +145,7 @@
     private boolean customBlobStore;
 
     @Override
-    protected synchronized SegmentNodeStore getNodeStore() {
+    protected SegmentNodeStore getNodeStore() {
         checkState(delegate != null, "service must be activated when used");
         return delegate;
     }
@@ -299,14 +299,8 @@
     }
 
     @Deactivate
-    public synchronized void deactivate() {
+    public void deactivate() {
         unregisterNodeStore();
-
-        observerTracker.stop();
-        delegate = null;
-
-        store.close();
-        store = null;
     }
 
     protected void bindBlobStore(BlobStore blobStore) throws IOException {
@@ -320,11 +314,17 @@
     }
 
     private void unregisterNodeStore() {
-        if(providerRegistration != null){
+        observerTracker.stop();
+        delegate = null;
+
+        if (providerRegistration != null) {
             providerRegistration.unregister();
             providerRegistration = null;
         }
-        if(storeRegistration != null){
+        if (storeRegistration != null) {
+            // this call can trigger a deadlock with the #getNodeStore() method
+            // being called from other OSGi services whenever there's a change
+            // in the NodeStore service registration
             storeRegistration.unregister();
             storeRegistration = null;
         }
@@ -348,6 +348,8 @@
             executor.stop();
             executor = null;
         }
+        store.close();
+        store = null;
     }
 
     /**