diff --git a/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/GrpcControllerImpl.java b/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/GrpcControllerImpl.java
index fb1e7ee..91b9db0 100644
--- a/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/GrpcControllerImpl.java
+++ b/protocols/grpc/ctl/src/main/java/org/onosproject/grpc/ctl/GrpcControllerImpl.java
@@ -16,7 +16,9 @@
 
 package org.onosproject.grpc.ctl;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Maps;
 import io.grpc.CallOptions;
 import io.grpc.Channel;
 import io.grpc.ClientCall;
@@ -51,6 +53,10 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * Default implementation of the GrpcController.
@@ -71,6 +77,7 @@
     private Map<GrpcStreamObserverId, GrpcObserverHandler> observers;
     private Map<GrpcChannelId, ManagedChannel> channels;
     private Map<GrpcChannelId, ManagedChannelBuilder<?>> channelBuilders;
+    private final Map<GrpcChannelId, Lock> channelLocks = Maps.newConcurrentMap();
 
     @Activate
     public void activate() {
@@ -109,20 +116,26 @@
     @Override
     public ManagedChannel connectChannel(GrpcChannelId channelId, ManagedChannelBuilder<?> channelBuilder)
             throws IOException {
+        checkNotNull(channelId);
+        checkNotNull(channelBuilder);
 
-        if (enableMessageLog) {
-            channelBuilder.intercept(new InternalLogChannelInterceptor(channelId));
+        Lock lock = channelLocks.computeIfAbsent(channelId, k -> new ReentrantLock());
+        lock.lock();
+
+        try {
+            if (enableMessageLog) {
+                channelBuilder.intercept(new InternalLogChannelInterceptor(channelId));
+            }
+            ManagedChannel channel = channelBuilder.build();
+            // Forced connection not yet implemented. Use workaround...
+            // channel.getState(true);
+            doDummyMessage(channel);
+            channelBuilders.put(channelId, channelBuilder);
+            channels.put(channelId, channel);
+            return channel;
+        } finally {
+            lock.unlock();
         }
-
-        ManagedChannel channel = channelBuilder.build();
-
-        // Forced connection not yet implemented. Use workaround...
-        // channel.getState(true);
-        doDummyMessage(channel);
-
-        channelBuilders.put(channelId, channelBuilder);
-        channels.put(channelId, channel);
-        return channel;
     }
 
     private void doDummyMessage(ManagedChannel channel) throws IOException {
@@ -141,45 +154,63 @@
 
     @Override
     public boolean isChannelOpen(GrpcChannelId channelId) {
-        if (!channels.containsKey(channelId)) {
-            log.warn("Can't check if channel open for unknown channel id {}", channelId);
-            return false;
-        }
+        checkNotNull(channelId);
+
+        Lock lock = channelLocks.computeIfAbsent(channelId, k -> new ReentrantLock());
+        lock.lock();
 
         try {
-            doDummyMessage(channels.get(channelId));
-            return true;
-        } catch (IOException e) {
-            return false;
+            if (!channels.containsKey(channelId)) {
+                log.warn("Can't check if channel open for unknown channel id {}", channelId);
+                return false;
+            }
+            try {
+                doDummyMessage(channels.get(channelId));
+                return true;
+            } catch (IOException e) {
+                return false;
+            }
+        } finally {
+            lock.unlock();
         }
     }
 
     @Override
     public void disconnectChannel(GrpcChannelId channelId) {
-        if (!channels.containsKey(channelId)) {
-            // Nothing to do.
-            return;
-        }
-        ManagedChannel channel = channels.get(channelId);
+        checkNotNull(channelId);
+
+        Lock lock = channelLocks.computeIfAbsent(channelId, k -> new ReentrantLock());
+        lock.lock();
 
         try {
-            channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
-        } catch (InterruptedException e) {
-            log.warn("Channel {} didn't shut down in time.");
-            channel.shutdownNow();
-        }
+            if (!channels.containsKey(channelId)) {
+                // Nothing to do.
+                return;
+            }
+            ManagedChannel channel = channels.get(channelId);
 
-        channels.remove(channelId);
-        channelBuilders.remove(channelId);
+            try {
+                channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
+            } catch (InterruptedException e) {
+                log.warn("Channel {} didn't shut down in time.");
+                channel.shutdownNow();
+            }
+
+            channels.remove(channelId);
+            channelBuilders.remove(channelId);
+        } finally {
+            lock.unlock();
+        }
     }
 
     @Override
     public Map<GrpcChannelId, ManagedChannel> getChannels() {
-        return channels;
+        return ImmutableMap.copyOf(channels);
     }
 
     @Override
     public Collection<ManagedChannel> getChannels(final DeviceId deviceId) {
+        checkNotNull(deviceId);
         final Set<ManagedChannel> deviceChannels = new HashSet<>();
         channels.forEach((k, v) -> {
             if (k.deviceId().equals(deviceId)) {
@@ -192,7 +223,16 @@
 
     @Override
     public Optional<ManagedChannel> getChannel(GrpcChannelId channelId) {
-        return Optional.ofNullable(channels.get(channelId));
+        checkNotNull(channelId);
+
+        Lock lock = channelLocks.computeIfAbsent(channelId, k -> new ReentrantLock());
+        lock.lock();
+
+        try {
+            return Optional.ofNullable(channels.get(channelId));
+        } finally {
+            lock.unlock();
+        }
     }
 
     /**