diff --git a/api/src/main/java/io/grpc/LoadBalancer.java b/api/src/main/java/io/grpc/LoadBalancer.java
index 36568a85f4..479ca4b2a8 100644
--- a/api/src/main/java/io/grpc/LoadBalancer.java
+++ b/api/src/main/java/io/grpc/LoadBalancer.java
@@ -694,6 +694,10 @@ public abstract class LoadBalancer {
      * Equivalent to {@link #updateSubchannelAddresses(io.grpc.LoadBalancer.Subchannel, List)} with
      * the given single {@code EquivalentAddressGroup}.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * @since 1.4.0
      */
     public final void updateSubchannelAddresses(
@@ -707,6 +711,10 @@ public abstract class LoadBalancer {
      * {@link #createSubchannel} when the new and old addresses overlap, since the subchannel can
      * continue using an existing connection.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * @throws IllegalArgumentException if {@code subchannel} was not returned from {@link
      *     #createSubchannel} or {@code addrs} is empty
      * @since 1.14.0
@@ -776,6 +784,10 @@ public abstract class LoadBalancer {
      * updateBalancingState()} has never been called, the channel will buffer all RPCs until a
      * picker is provided.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * <p>The passed state will be the channel's new state. The SHUTDOWN state should not be passed
      * and its behavior is undefined.
      *
@@ -787,6 +799,10 @@ public abstract class LoadBalancer {
     /**
      * Call {@link NameResolver#refresh} on the channel's resolver.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * @since 1.18.0
      */
     public void refreshNameResolution() {
@@ -903,6 +919,10 @@ public abstract class LoadBalancer {
      * Shuts down the Subchannel.  After this method is called, this Subchannel should no longer
      * be returned by the latest {@link SubchannelPicker picker}, and can be safely discarded.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * @since 1.2.0
      */
     public abstract void shutdown();
@@ -910,6 +930,10 @@ public abstract class LoadBalancer {
     /**
      * Asks the Subchannel to create a connection (aka transport), if there isn't an active one.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * @since 1.2.0
      */
     public abstract void requestConnection();
@@ -919,6 +943,10 @@ public abstract class LoadBalancer {
      * the Subchannel has only one {@link EquivalentAddressGroup}.  Under the hood it calls
      * {@link #getAllAddresses}.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * @throws IllegalStateException if this subchannel has more than one EquivalentAddressGroup.
      *         Use {@link #getAllAddresses} instead
      * @since 1.2.0
@@ -932,6 +960,10 @@ public abstract class LoadBalancer {
     /**
      * Returns the addresses that this Subchannel is bound to. The returned list will not be empty.
      *
+     * <p>It should be called from the Synchronization Context.  Currently will log a warning if
+     * violated.  It will become an exception eventually.  See <a
+     * href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for the background.
+     *
      * @since 1.14.0
      */
     public List<EquivalentAddressGroup> getAllAddresses() {
diff --git a/core/src/main/java/io/grpc/internal/ManagedChannelImpl.java b/core/src/main/java/io/grpc/internal/ManagedChannelImpl.java
index d8a97a202a..ae7303697a 100644
--- a/core/src/main/java/io/grpc/internal/ManagedChannelImpl.java
+++ b/core/src/main/java/io/grpc/internal/ManagedChannelImpl.java
@@ -1048,14 +1048,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
     @Override
     public AbstractSubchannel createSubchannel(
         List<EquivalentAddressGroup> addressGroups, Attributes attrs) {
-      try {
-        syncContext.throwIfNotInThisSynchronizationContext();
-      } catch (IllegalStateException e) {
-        logger.log(Level.WARNING,
-            "We sugguest you call createSubchannel() from SynchronizationContext."
-            + " Otherwise, it may race with handleSubchannelState()."
-            + " See https://github.com/grpc/grpc-java/issues/5015", e);
-      }
+      logWarningIfNotInSyncContext("createSubchannel()");
       checkNotNull(addressGroups, "addressGroups");
       checkNotNull(attrs, "attrs");
       // TODO(ejona): can we be even stricter? Like loadBalancer == null?
@@ -1149,6 +1142,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
         final ConnectivityState newState, final SubchannelPicker newPicker) {
       checkNotNull(newState, "newState");
       checkNotNull(newPicker, "newPicker");
+      logWarningIfNotInSyncContext("updateBalancingState()");
       final class UpdateBalancingState implements Runnable {
         @Override
         public void run() {
@@ -1170,6 +1164,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
 
     @Override
     public void refreshNameResolution() {
+      logWarningIfNotInSyncContext("refreshNameResolution()");
       final class LoadBalancerRefreshNameResolution implements Runnable {
         @Override
         public void run() {
@@ -1185,6 +1180,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
         LoadBalancer.Subchannel subchannel, List<EquivalentAddressGroup> addrs) {
       checkArgument(subchannel instanceof SubchannelImpl,
           "subchannel must have been returned from createSubchannel");
+      logWarningIfNotInSyncContext("updateSubchannelAddresses()");
       ((SubchannelImpl) subchannel).subchannel.updateAddresses(addrs);
     }
 
@@ -1478,6 +1474,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
 
     @Override
     public void shutdown() {
+      logWarningIfNotInSyncContext("Subchannel.shutdown()");
       synchronized (shutdownLock) {
         if (shutdownRequested) {
           if (terminating && delayedShutdownTask != null) {
@@ -1521,11 +1518,13 @@ final class ManagedChannelImpl extends ManagedChannel implements
 
     @Override
     public void requestConnection() {
+      logWarningIfNotInSyncContext("Subchannel.requestConnection()");
       subchannel.obtainActiveTransport();
     }
 
     @Override
     public List<EquivalentAddressGroup> getAllAddresses() {
+      logWarningIfNotInSyncContext("Subchannel.getAllAddresses()");
       return subchannel.getAddressGroups();
     }
 
@@ -1784,4 +1783,15 @@ final class ManagedChannelImpl extends ManagedChannel implements
       }
     }
   }
+
+  private void logWarningIfNotInSyncContext(String method) {
+    try {
+      syncContext.throwIfNotInThisSynchronizationContext();
+    } catch (IllegalStateException e) {
+      logger.log(Level.WARNING,
+          method + " should be called from SynchronizationContext. "
+          + "This warning will become an exception in a future release. "
+          + "See https://github.com/grpc/grpc-java/issues/5015 for more details", e);
+    }
+  }
 }
diff --git a/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java b/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java
index d7ba03a9fc..f1f0d4e0d7 100644
--- a/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java
+++ b/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java
@@ -38,6 +38,7 @@ import io.grpc.CallOptions;
 import io.grpc.ChannelLogger;
 import io.grpc.ClientCall;
 import io.grpc.ClientInterceptor;
+import io.grpc.ConnectivityState;
 import io.grpc.EquivalentAddressGroup;
 import io.grpc.IntegerMarshaller;
 import io.grpc.LoadBalancer;
@@ -310,14 +311,14 @@ public class ManagedChannelImplIdlenessTest {
 
     // Assume LoadBalancer has received an address, then create a subchannel.
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo t0 = newTransports.poll();
     t0.listener.transportReady();
 
     SubchannelPicker mockPicker = mock(SubchannelPicker.class);
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     // Delayed transport creates real streams in the app executor
     executor.runDueTasks();
 
@@ -350,13 +351,13 @@ public class ManagedChannelImplIdlenessTest {
     Helper helper = helperCaptor.getValue();
     Subchannel subchannel = createSubchannelSafely(helper, servers.get(0), Attributes.EMPTY);
 
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo t0 = newTransports.poll();
     t0.listener.transportReady();
 
-    helper.updateSubchannelAddresses(subchannel, servers.get(1));
+    updateSubchannelAddressesSafely(helper, subchannel, servers.get(1));
 
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo t1 = newTransports.poll();
     t1.listener.transportReady();
   }
@@ -370,15 +371,15 @@ public class ManagedChannelImplIdlenessTest {
     Helper helper = helperCaptor.getValue();
     Subchannel subchannel = createSubchannelSafely(helper, servers.get(0), Attributes.EMPTY);
 
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo t0 = newTransports.poll();
     t0.listener.transportReady();
 
     List<SocketAddress> changedList = new ArrayList<>(servers.get(0).getAddresses());
     changedList.add(new FakeSocketAddress("aDifferentServer"));
-    helper.updateSubchannelAddresses(subchannel, new EquivalentAddressGroup(changedList));
+    updateSubchannelAddressesSafely(helper, subchannel, new EquivalentAddressGroup(changedList));
 
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     assertNull(newTransports.poll());
   }
 
@@ -397,7 +398,7 @@ public class ManagedChannelImplIdlenessTest {
     SubchannelPicker failingPicker = mock(SubchannelPicker.class);
     when(failingPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withError(Status.UNAVAILABLE));
-    helper.updateBalancingState(TRANSIENT_FAILURE, failingPicker);
+    updateBalancingStateSafely(helper, TRANSIENT_FAILURE, failingPicker);
     executor.runDueTasks();
     verify(mockCallListener).onClose(same(Status.UNAVAILABLE), any(Metadata.class));
 
@@ -499,7 +500,7 @@ public class ManagedChannelImplIdlenessTest {
     }
   }
 
-  // We need this because createSubchannel() should be called from the SynchronizationContext
+  // Helper methods to call methods from SynchronizationContext
   private static Subchannel createSubchannelSafely(
       final Helper helper, final EquivalentAddressGroup addressGroup, final Attributes attrs) {
     final AtomicReference<Subchannel> resultCapture = new AtomicReference<>();
@@ -512,4 +513,36 @@ public class ManagedChannelImplIdlenessTest {
         });
     return resultCapture.get();
   }
+
+  private static void requestConnectionSafely(Helper helper, final Subchannel subchannel) {
+    helper.getSynchronizationContext().execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            subchannel.requestConnection();
+          }
+        });
+  }
+
+  private static void updateBalancingStateSafely(
+      final Helper helper, final ConnectivityState state, final SubchannelPicker picker) {
+    helper.getSynchronizationContext().execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            helper.updateBalancingState(state, picker);
+          }
+        });
+  }
+
+  private static void updateSubchannelAddressesSafely(
+      final Helper helper, final Subchannel subchannel, final EquivalentAddressGroup addrs) {
+    helper.getSynchronizationContext().execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            helper.updateSubchannelAddresses(subchannel, addrs);
+          }
+        });
+  }
 }
diff --git a/core/src/test/java/io/grpc/internal/ManagedChannelImplTest.java b/core/src/test/java/io/grpc/internal/ManagedChannelImplTest.java
index 67f9273fe9..60c13d0b2c 100644
--- a/core/src/test/java/io/grpc/internal/ManagedChannelImplTest.java
+++ b/core/src/test/java/io/grpc/internal/ManagedChannelImplTest.java
@@ -360,7 +360,7 @@ public class ManagedChannelImplTest {
       LogRecord record = logRef.get();
       assertThat(record.getLevel()).isEqualTo(Level.WARNING);
       assertThat(record.getMessage()).contains(
-          "We sugguest you call createSubchannel() from SynchronizationContext");
+          "createSubchannel() should be called from SynchronizationContext");
       assertThat(record.getThrown()).isInstanceOf(IllegalStateException.class);
     } finally {
       logger.removeHandler(handler);
@@ -434,7 +434,7 @@ public class ManagedChannelImplTest {
     assertThat(getStats(channel).subchannels)
         .containsExactly(subchannel.getInternalSubchannel());
 
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo transportInfo = transports.poll();
     assertNotNull(transportInfo);
     assertTrue(channelz.containsClientSocket(transportInfo.transport.getLogId()));
@@ -445,7 +445,7 @@ public class ManagedChannelImplTest {
 
     // terminate subchannel
     assertTrue(channelz.containsSubchannel(subchannel.getInternalSubchannel().getLogId()));
-    subchannel.shutdown();
+    shutdownSafely(helper, subchannel);
     timer.forwardTime(ManagedChannelImpl.SUBCHANNEL_SHUTDOWN_DELAY_SECONDS, TimeUnit.SECONDS);
     timer.runDueTasks();
     assertFalse(channelz.containsSubchannel(subchannel.getInternalSubchannel().getLogId()));
@@ -520,7 +520,7 @@ public class ManagedChannelImplTest {
     // Configure the picker so that first RPC goes to delayed transport, and second RPC goes to
     // real transport.
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     verify(mockTransportFactory)
         .newClientTransport(
             any(SocketAddress.class), any(ClientTransportOptions.class), any(ChannelLogger.class));
@@ -539,7 +539,7 @@ public class ManagedChannelImplTest {
     when(mockPicker.pickSubchannel(
         new PickSubchannelArgsImpl(method, headers2, CallOptions.DEFAULT))).thenReturn(
         PickResult.withSubchannel(subchannel));
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
 
     // First RPC, will be pending
     ClientCall<String, Integer> call = channel.newCall(method, CallOptions.DEFAULT);
@@ -598,7 +598,7 @@ public class ManagedChannelImplTest {
       SubchannelPicker picker2 = mock(SubchannelPicker.class);
       when(picker2.pickSubchannel(new PickSubchannelArgsImpl(method, headers, CallOptions.DEFAULT)))
           .thenReturn(PickResult.withSubchannel(subchannel));
-      helper.updateBalancingState(READY, picker2);
+      updateBalancingStateSafely(helper, READY, picker2);
       executor.runDueTasks();
       verify(mockTransport).newStream(same(method), same(headers), same(CallOptions.DEFAULT));
       verify(mockStream).start(any(ClientStreamListener.class));
@@ -616,7 +616,7 @@ public class ManagedChannelImplTest {
       verify(mockTransport, never()).shutdownNow(any(Status.class));
     }
     // LoadBalancer should shutdown the subchannel
-    subchannel.shutdown();
+    shutdownSafely(helper, subchannel);
     if (shutdownNow) {
       verify(mockTransport).shutdown(same(ManagedChannelImpl.SHUTDOWN_NOW_STATUS));
     } else {
@@ -660,8 +660,8 @@ public class ManagedChannelImplTest {
 
     Subchannel subchannel1 = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
     Subchannel subchannel2 = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel1.requestConnection();
-    subchannel2.requestConnection();
+    requestConnectionSafely(helper, subchannel1);
+    requestConnectionSafely(helper, subchannel2);
     verify(mockTransportFactory, times(2))
         .newClientTransport(
             any(SocketAddress.class), any(ClientTransportOptions.class), any(ChannelLogger.class));
@@ -729,7 +729,7 @@ public class ManagedChannelImplTest {
     verify(mockTransportFactory, never())
         .newClientTransport(
             any(SocketAddress.class), any(ClientTransportOptions.class), any(ChannelLogger.class));
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     verify(mockTransportFactory)
         .newClientTransport(
             any(SocketAddress.class), any(ClientTransportOptions.class), any(ChannelLogger.class));
@@ -742,7 +742,7 @@ public class ManagedChannelImplTest {
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
     assertEquals(0, callExecutor.numPendingTasks());
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
 
     // Real streams are started in the call executor if they were previously buffered.
     assertEquals(1, callExecutor.runDueTasks());
@@ -763,7 +763,7 @@ public class ManagedChannelImplTest {
     transportListener.transportTerminated();
 
     // Clean up as much as possible to allow the channel to terminate.
-    subchannel.shutdown();
+    shutdownSafely(helper, subchannel);
     timer.forwardNanos(
         TimeUnit.SECONDS.toNanos(ManagedChannelImpl.SUBCHANNEL_SHUTDOWN_DELAY_SECONDS));
   }
@@ -843,7 +843,7 @@ public class ManagedChannelImplTest {
     Status status = Status.UNAVAILABLE.withDescription("for test");
     when(picker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withDrop(status));
-    helper.updateBalancingState(READY, picker);
+    updateBalancingStateSafely(helper, READY, picker);
     executor.runDueTasks();
     verify(mockCallListener).onClose(same(status), any(Metadata.class));
 
@@ -987,7 +987,7 @@ public class ManagedChannelImplTest {
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     inOrder.verify(mockLoadBalancer).handleSubchannelState(
         same(subchannel), stateInfoCaptor.capture());
     assertEquals(CONNECTING, stateInfoCaptor.getValue().getState());
@@ -1020,7 +1020,7 @@ public class ManagedChannelImplTest {
     assertEquals(READY, stateInfoCaptor.getValue().getState());
 
     // A typical LoadBalancer will call this once the subchannel becomes READY
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     // Delayed transport uses the app executor to create real streams.
     executor.runDueTasks();
 
@@ -1069,7 +1069,7 @@ public class ManagedChannelImplTest {
 
     when(picker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(drop ? PickResult.withDrop(status) : PickResult.withError(status));
-    helper.updateBalancingState(READY, picker);
+    updateBalancingStateSafely(helper, READY, picker);
 
     executor.runDueTasks();
     if (shouldFail) {
@@ -1137,7 +1137,7 @@ public class ManagedChannelImplTest {
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
 
     inOrder.verify(mockLoadBalancer).handleSubchannelState(
         same(subchannel), stateInfoCaptor.capture());
@@ -1172,7 +1172,7 @@ public class ManagedChannelImplTest {
     SubchannelPicker picker2 = mock(SubchannelPicker.class);
     when(picker2.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withError(server2Error));
-    helper.updateBalancingState(TRANSIENT_FAILURE, picker2);
+    updateBalancingStateSafely(helper, TRANSIENT_FAILURE, picker2);
     executor.runDueTasks();
 
     // ... which fails the fail-fast call
@@ -1193,14 +1193,24 @@ public class ManagedChannelImplTest {
     // createSubchannel() always return a new Subchannel
     Attributes attrs1 = Attributes.newBuilder().set(SUBCHANNEL_ATTR_KEY, "attr1").build();
     Attributes attrs2 = Attributes.newBuilder().set(SUBCHANNEL_ATTR_KEY, "attr2").build();
-    Subchannel sub1 = createSubchannelSafely(helper, addressGroup, attrs1);
-    Subchannel sub2 = createSubchannelSafely(helper, addressGroup, attrs2);
+    final Subchannel sub1 = createSubchannelSafely(helper, addressGroup, attrs1);
+    final Subchannel sub2 = createSubchannelSafely(helper, addressGroup, attrs2);
     assertNotSame(sub1, sub2);
     assertNotSame(attrs1, attrs2);
     assertSame(attrs1, sub1.getAttributes());
     assertSame(attrs2, sub2.getAttributes());
-    assertSame(addressGroup, sub1.getAddresses());
-    assertSame(addressGroup, sub2.getAddresses());
+
+    final AtomicBoolean snippetPassed = new AtomicBoolean(false);
+    helper.getSynchronizationContext().execute(new Runnable() {
+        @Override
+        public void run() {
+          // getAddresses() must be called from sync context
+          assertSame(addressGroup, sub1.getAddresses());
+          assertSame(addressGroup, sub2.getAddresses());
+          snippetPassed.set(true);
+        }
+      });
+    assertThat(snippetPassed.get()).isTrue();
 
     // requestConnection()
     verify(mockTransportFactory, never())
@@ -1208,7 +1218,7 @@ public class ManagedChannelImplTest {
             any(SocketAddress.class),
             any(ClientTransportOptions.class),
             any(TransportLogger.class));
-    sub1.requestConnection();
+    requestConnectionSafely(helper, sub1);
     verify(mockTransportFactory)
         .newClientTransport(
             eq(socketAddress),
@@ -1217,7 +1227,7 @@ public class ManagedChannelImplTest {
     MockClientTransportInfo transportInfo1 = transports.poll();
     assertNotNull(transportInfo1);
 
-    sub2.requestConnection();
+    requestConnectionSafely(helper, sub2);
     verify(mockTransportFactory, times(2))
         .newClientTransport(
             eq(socketAddress),
@@ -1226,17 +1236,17 @@ public class ManagedChannelImplTest {
     MockClientTransportInfo transportInfo2 = transports.poll();
     assertNotNull(transportInfo2);
 
-    sub1.requestConnection();
-    sub2.requestConnection();
+    requestConnectionSafely(helper, sub1);
+    requestConnectionSafely(helper, sub2);
     // The subchannel doesn't matter since this isn't called
     verify(mockTransportFactory, times(2))
         .newClientTransport(
             eq(socketAddress), eq(clientTransportOptions), isA(TransportLogger.class));
 
     // shutdown() has a delay
-    sub1.shutdown();
+    shutdownSafely(helper, sub1);
     timer.forwardTime(ManagedChannelImpl.SUBCHANNEL_SHUTDOWN_DELAY_SECONDS - 1, TimeUnit.SECONDS);
-    sub1.shutdown();
+    shutdownSafely(helper, sub1);
     verify(transportInfo1.transport, never()).shutdown(any(Status.class));
     timer.forwardTime(1, TimeUnit.SECONDS);
     verify(transportInfo1.transport).shutdown(same(ManagedChannelImpl.SUBCHANNEL_SHUTDOWN_STATUS));
@@ -1247,7 +1257,7 @@ public class ManagedChannelImplTest {
     verify(mockLoadBalancer).shutdown();
     verify(transportInfo2.transport, never()).shutdown(any(Status.class));
 
-    sub2.shutdown();
+    shutdownSafely(helper, sub2);
     verify(transportInfo2.transport).shutdown(same(ManagedChannelImpl.SHUTDOWN_STATUS));
 
     // Cleanup
@@ -1263,8 +1273,8 @@ public class ManagedChannelImplTest {
     createChannel();
     Subchannel sub1 = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
     Subchannel sub2 = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    sub1.requestConnection();
-    sub2.requestConnection();
+    requestConnectionSafely(helper, sub1);
+    requestConnectionSafely(helper, sub2);
 
     assertThat(transports).hasSize(2);
     MockClientTransportInfo ti1 = transports.poll();
@@ -1294,9 +1304,9 @@ public class ManagedChannelImplTest {
 
     channel.shutdown();
     verify(mockLoadBalancer).shutdown();
-    sub1.shutdown();
+    shutdownSafely(helper, sub1);
     assertFalse(channel.isTerminated());
-    sub2.shutdown();
+    shutdownSafely(helper, sub2);
     assertTrue(channel.isTerminated());
     verify(mockTransportFactory, never())
         .newClientTransport(
@@ -1499,7 +1509,7 @@ public class ManagedChannelImplTest {
     CallOptions callOptions = CallOptions.DEFAULT.withDeadlineAfter(5, TimeUnit.SECONDS);
 
     // Subchannel must be READY when creating the RPC.
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     verify(mockTransportFactory)
         .newClientTransport(
             any(SocketAddress.class), any(ClientTransportOptions.class), any(ChannelLogger.class));
@@ -1524,7 +1534,7 @@ public class ManagedChannelImplTest {
     Channel sChannel = subchannel.asChannel();
     Metadata headers = new Metadata();
 
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     verify(mockTransportFactory)
         .newClientTransport(
             any(SocketAddress.class), any(ClientTransportOptions.class), any(ChannelLogger.class));
@@ -1553,7 +1563,7 @@ public class ManagedChannelImplTest {
     Metadata headers = new Metadata();
 
     // Subchannel must be READY when creating the RPC.
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     verify(mockTransportFactory)
         .newClientTransport(
             any(SocketAddress.class), any(ClientTransportOptions.class), any(ChannelLogger.class));
@@ -1656,7 +1666,7 @@ public class ManagedChannelImplTest {
       oobChannel.getSubchannel().requestConnection();
     } else {
       Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-      subchannel.requestConnection();
+      requestConnectionSafely(helper, subchannel);
     }
 
     MockClientTransportInfo transportInfo = transports.poll();
@@ -1743,7 +1753,7 @@ public class ManagedChannelImplTest {
     // Simulate name resolution results
     EquivalentAddressGroup addressGroup = new EquivalentAddressGroup(socketAddress);
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     verify(mockTransportFactory)
         .newClientTransport(
             same(socketAddress), eq(clientTransportOptions), any(ChannelLogger.class));
@@ -1766,7 +1776,7 @@ public class ManagedChannelImplTest {
     transportInfo.listener.transportReady();
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     executor.runDueTasks();
     ArgumentCaptor<RequestInfo> infoCaptor = ArgumentCaptor.forClass(null);
     ArgumentCaptor<CallCredentials.MetadataApplier> applierCaptor = ArgumentCaptor.forClass(null);
@@ -1816,7 +1826,7 @@ public class ManagedChannelImplTest {
     ClientStreamTracer.Factory factory2 = mock(ClientStreamTracer.Factory.class);
     createChannel();
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo transportInfo = transports.poll();
     transportInfo.listener.transportReady();
     ClientTransport mockTransport = transportInfo.transport;
@@ -1826,7 +1836,7 @@ public class ManagedChannelImplTest {
 
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class))).thenReturn(
         PickResult.withSubchannel(subchannel, factory2));
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
 
     CallOptions callOptions = CallOptions.DEFAULT.withStreamTracerFactory(factory1);
     ClientCall<String, Integer> call = channel.newCall(method, callOptions);
@@ -1854,7 +1864,7 @@ public class ManagedChannelImplTest {
     call.start(mockCallListener, new Metadata());
 
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo transportInfo = transports.poll();
     transportInfo.listener.transportReady();
     ClientTransport mockTransport = transportInfo.transport;
@@ -1864,7 +1874,7 @@ public class ManagedChannelImplTest {
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class))).thenReturn(
         PickResult.withSubchannel(subchannel, factory2));
 
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     assertEquals(1, executor.runDueTasks());
 
     verify(mockPicker).pickSubchannel(any(PickSubchannelArgs.class));
@@ -1884,7 +1894,7 @@ public class ManagedChannelImplTest {
     createChannel();
     assertEquals(IDLE, channel.getState(false));
 
-    helper.updateBalancingState(TRANSIENT_FAILURE, mockPicker);
+    updateBalancingStateSafely(helper, TRANSIENT_FAILURE, mockPicker);
     assertEquals(TRANSIENT_FAILURE, channel.getState(false));
   }
 
@@ -1904,7 +1914,7 @@ public class ManagedChannelImplTest {
     verify(mockLoadBalancerProvider).newLoadBalancer(helperCaptor.capture());
     helper = helperCaptor.getValue();
 
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     assertEquals(CONNECTING, channel.getState(false));
     assertEquals(CONNECTING, channel.getState(true));
     verify(mockLoadBalancerProvider).newLoadBalancer(any(Helper.class));
@@ -1917,7 +1927,7 @@ public class ManagedChannelImplTest {
     createChannel();
     verify(mockLoadBalancerProvider).newLoadBalancer(any(Helper.class));
 
-    helper.updateBalancingState(IDLE, mockPicker);
+    updateBalancingStateSafely(helper, IDLE, mockPicker);
 
     assertEquals(IDLE, channel.getState(true));
     verify(mockLoadBalancerProvider).newLoadBalancer(any(Helper.class));
@@ -1944,7 +1954,7 @@ public class ManagedChannelImplTest {
     assertFalse(stateChanged.get());
 
     // state change from IDLE to CONNECTING
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     // onStateChanged callback should run
     executor.runDueTasks();
     assertTrue(stateChanged.get());
@@ -1982,7 +1992,7 @@ public class ManagedChannelImplTest {
 
     stateChanged.set(false);
     channel.notifyWhenStateChanged(SHUTDOWN, onStateChanged);
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
 
     assertEquals(SHUTDOWN, channel.getState(false));
     executor.runDueTasks();
@@ -1996,7 +2006,7 @@ public class ManagedChannelImplTest {
     createChannel();
     assertEquals(IDLE, channel.getState(false));
 
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     assertEquals(CONNECTING, channel.getState(false));
 
     timer.forwardNanos(TimeUnit.MILLISECONDS.toNanos(idleTimeoutMillis));
@@ -2040,7 +2050,7 @@ public class ManagedChannelImplTest {
     if (initialState == IDLE) {
       timer.forwardNanos(TimeUnit.MILLISECONDS.toNanos(idleTimeoutMillis));
     } else {
-      helper.updateBalancingState(initialState, mockPicker);
+      updateBalancingStateSafely(helper, initialState, mockPicker);
     }
     assertEquals(initialState, channel.getState(false));
 
@@ -2083,7 +2093,7 @@ public class ManagedChannelImplTest {
 
     // A misbehaving balancer that calls updateBalancingState() after it's shut down will not be
     // able to revive it.
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     verifyPanicMode(panicReason);
 
     // Cannot be revived by exitIdleMode()
@@ -2106,7 +2116,7 @@ public class ManagedChannelImplTest {
 
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withNoResult());
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
 
     // Start RPCs that will be buffered in delayedTransport
     ClientCall<String, Integer> call =
@@ -2180,10 +2190,10 @@ public class ManagedChannelImplTest {
 
     // Updating on the old helper (whose balancer has been shutdown) does not change the channel
     // state.
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     assertEquals(IDLE, channel.getState(false));
 
-    helper2.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper2, CONNECTING, mockPicker);
     assertEquals(CONNECTING, channel.getState(false));
   }
 
@@ -2207,7 +2217,7 @@ public class ManagedChannelImplTest {
     // Move channel into TRANSIENT_FAILURE, which will fail the pending call
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withError(pickError));
-    helper.updateBalancingState(TRANSIENT_FAILURE, mockPicker);
+    updateBalancingStateSafely(helper, TRANSIENT_FAILURE, mockPicker);
     assertEquals(TRANSIENT_FAILURE, channel.getState(false));
     executor.runDueTasks();
     verify(mockCallListener).onClose(same(pickError), any(Metadata.class));
@@ -2229,7 +2239,7 @@ public class ManagedChannelImplTest {
 
     // Establish a connection
     Subchannel subchannel = createSubchannelSafely(helper2, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo transportInfo = transports.poll();
     ConnectionClientTransport mockTransport = transportInfo.transport;
     ManagedClientTransport.Listener transportListener = transportInfo.listener;
@@ -2239,7 +2249,7 @@ public class ManagedChannelImplTest {
 
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    helper2.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper2, READY, mockPicker);
     assertEquals(READY, channel.getState(false));
     executor.runDueTasks();
 
@@ -2251,7 +2261,7 @@ public class ManagedChannelImplTest {
   @Test
   public void enterIdleEntersIdle() {
     createChannel();
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     assertEquals(READY, channel.getState(false));
 
     channel.enterIdle();
@@ -2297,7 +2307,7 @@ public class ManagedChannelImplTest {
 
     // Establish a connection
     Subchannel subchannel = createSubchannelSafely(helper2, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     ClientStream mockStream = mock(ClientStream.class);
     MockClientTransportInfo transportInfo = transports.poll();
     ConnectionClientTransport mockTransport = transportInfo.transport;
@@ -2307,7 +2317,7 @@ public class ManagedChannelImplTest {
     transportListener.transportReady();
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    helper2.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper2, READY, mockPicker);
     assertEquals(READY, channel.getState(false));
 
     // Verify the original call was drained
@@ -2327,7 +2337,7 @@ public class ManagedChannelImplTest {
     // Make the transport available with subchannel2
     Subchannel subchannel1 = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
     Subchannel subchannel2 = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel2.requestConnection();
+    requestConnectionSafely(helper, subchannel2);
 
     MockClientTransportInfo transportInfo = transports.poll();
     ConnectionClientTransport mockTransport = transportInfo.transport;
@@ -2338,7 +2348,7 @@ public class ManagedChannelImplTest {
 
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel1));
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
 
     executor.runDueTasks();
     verify(mockTransport, never())
@@ -2348,7 +2358,7 @@ public class ManagedChannelImplTest {
 
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel2));
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
 
     executor.runDueTasks();
     verify(mockTransport).newStream(same(method), any(Metadata.class), any(CallOptions.class));
@@ -2365,7 +2375,7 @@ public class ManagedChannelImplTest {
     Runnable onStateChanged = mock(Runnable.class);
     channel.notifyWhenStateChanged(IDLE, onStateChanged);
 
-    helper.updateBalancingState(SHUTDOWN, mockPicker);
+    updateBalancingStateSafely(helper, SHUTDOWN, mockPicker);
 
     assertEquals(IDLE, channel.getState(false));
     executor.runDueTasks();
@@ -2381,7 +2391,7 @@ public class ManagedChannelImplTest {
 
     FakeNameResolverFactory.FakeNameResolver resolver = nameResolverFactory.resolvers.get(0);
     int initialRefreshCount = resolver.refreshCalled;
-    helper.refreshNameResolution();
+    refreshNameResolutionSafely(helper);
     assertEquals(initialRefreshCount + 1, resolver.refreshCalled);
   }
 
@@ -2648,7 +2658,7 @@ public class ManagedChannelImplTest {
     channelBuilder.maxTraceEvents(10);
     createChannel();
     timer.forwardNanos(1234);
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     assertThat(getStats(channel).channelTrace.events).contains(new ChannelTrace.Event.Builder()
         .setDescription("Entering CONNECTING state")
         .setSeverity(ChannelTrace.Event.Severity.CT_INFO)
@@ -2720,14 +2730,14 @@ public class ManagedChannelImplTest {
     helper = helperCaptor.getValue();
 
     assertEquals(IDLE, getStats(channel).state);
-    helper.updateBalancingState(CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     assertEquals(CONNECTING, getStats(channel).state);
 
     AbstractSubchannel subchannel =
         (AbstractSubchannel) createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
 
     assertEquals(IDLE, getStats(subchannel).state);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     assertEquals(CONNECTING, getStats(subchannel).state);
 
     MockClientTransportInfo transportInfo = transports.poll();
@@ -2737,7 +2747,7 @@ public class ManagedChannelImplTest {
     assertEquals(READY, getStats(subchannel).state);
 
     assertEquals(CONNECTING, getStats(channel).state);
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     assertEquals(READY, getStats(channel).state);
 
     channel.shutdownNow();
@@ -2779,7 +2789,7 @@ public class ManagedChannelImplTest {
     ClientStreamTracer.Factory factory = mock(ClientStreamTracer.Factory.class);
     AbstractSubchannel subchannel =
         (AbstractSubchannel) createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo transportInfo = transports.poll();
     transportInfo.listener.transportReady();
     ClientTransport mockTransport = transportInfo.transport;
@@ -2791,7 +2801,7 @@ public class ManagedChannelImplTest {
 
     // subchannel stat bumped when call gets assigned to it
     assertEquals(0, getStats(subchannel).callsStarted);
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
     assertEquals(1, executor.runDueTasks());
     verify(mockStream).start(streamListenerCaptor.capture());
     assertEquals(1, getStats(subchannel).callsStarted);
@@ -3018,7 +3028,7 @@ public class ManagedChannelImplTest {
     Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo transportInfo = transports.poll();
     ConnectionClientTransport mockTransport = transportInfo.transport;
     ClientStream mockStream = mock(ClientStream.class);
@@ -3026,7 +3036,7 @@ public class ManagedChannelImplTest {
     when(mockTransport.newStream(same(method), any(Metadata.class), any(CallOptions.class)))
         .thenReturn(mockStream).thenReturn(mockStream2);
     transportInfo.listener.transportReady();
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
 
     ArgumentCaptor<ClientStreamListener> streamListenerCaptor =
         ArgumentCaptor.forClass(ClientStreamListener.class);
@@ -3067,7 +3077,7 @@ public class ManagedChannelImplTest {
     streamListenerCaptor.getValue().closed(Status.INTERNAL, new Metadata());
     verify(mockLoadBalancer).shutdown();
     // simulating the shutdown of load balancer triggers the shutdown of subchannel
-    subchannel.shutdown();
+    shutdownSafely(helper, subchannel);
     transportInfo.listener.transportTerminated(); // simulating transport terminated
     assertTrue(
         "channel.isTerminated() is expected to be true but was false",
@@ -3114,10 +3124,10 @@ public class ManagedChannelImplTest {
             .build());
 
     // simulating request connection and then transport ready after resolved address
-    Subchannel subchannel = helper.createSubchannel(addressGroup, Attributes.EMPTY);
+    Subchannel subchannel = createSubchannelSafely(helper, addressGroup, Attributes.EMPTY);
     when(mockPicker.pickSubchannel(any(PickSubchannelArgs.class)))
         .thenReturn(PickResult.withSubchannel(subchannel));
-    subchannel.requestConnection();
+    requestConnectionSafely(helper, subchannel);
     MockClientTransportInfo transportInfo = transports.poll();
     ConnectionClientTransport mockTransport = transportInfo.transport;
     ClientStream mockStream = mock(ClientStream.class);
@@ -3125,7 +3135,7 @@ public class ManagedChannelImplTest {
     when(mockTransport.newStream(same(method), any(Metadata.class), any(CallOptions.class)))
         .thenReturn(mockStream).thenReturn(mockStream2);
     transportInfo.listener.transportReady();
-    helper.updateBalancingState(READY, mockPicker);
+    updateBalancingStateSafely(helper, READY, mockPicker);
 
     ArgumentCaptor<ClientStreamListener> streamListenerCaptor =
         ArgumentCaptor.forClass(ClientStreamListener.class);
@@ -3165,7 +3175,7 @@ public class ManagedChannelImplTest {
     assertThat(timer.numPendingTasks()).isEqualTo(0);
     verify(mockLoadBalancer).shutdown();
     // simulating the shutdown of load balancer triggers the shutdown of subchannel
-    subchannel.shutdown();
+    shutdownSafely(helper, subchannel);
     transportInfo.listener.transportTerminated(); // simulating transport terminated
     assertTrue(
         "channel.isTerminated() is expected to be true but was false",
@@ -3899,7 +3909,7 @@ public class ManagedChannelImplTest {
     return Iterables.getOnlyElement(timer.getPendingTasks(NAME_RESOLVER_REFRESH_TASK_FILTER), null);
   }
 
-  // We need this because createSubchannel() should be called from the SynchronizationContext
+  // Helper methods to call methods from SynchronizationContext
   private static Subchannel createSubchannelSafely(
       final Helper helper, final EquivalentAddressGroup addressGroup, final Attributes attrs) {
     final AtomicReference<Subchannel> resultCapture = new AtomicReference<>();
@@ -3913,6 +3923,48 @@ public class ManagedChannelImplTest {
     return resultCapture.get();
   }
 
+  private static void requestConnectionSafely(Helper helper, final Subchannel subchannel) {
+    helper.getSynchronizationContext().execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            subchannel.requestConnection();
+          }
+        });
+  }
+
+  private static void updateBalancingStateSafely(
+      final Helper helper, final ConnectivityState state, final SubchannelPicker picker) {
+    helper.getSynchronizationContext().execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            helper.updateBalancingState(state, picker);
+          }
+        });
+  }
+
+  private static void refreshNameResolutionSafely(final Helper helper) {
+    helper.getSynchronizationContext().execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            helper.refreshNameResolution();
+          }
+        });
+  }
+
+  private static void shutdownSafely(
+      final Helper helper, final Subchannel subchannel) {
+    helper.getSynchronizationContext().execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            subchannel.shutdown();
+          }
+        });
+  }
+
   @SuppressWarnings("unchecked")
   private static Map<String, Object> parseConfig(String json) throws Exception {
     return (Map<String, Object>) JsonParser.parse(json);