diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68dd1c9a2e..af063db3bb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ and what APIs have changed, if applicable.
 - Strictly enforce Gradle version compatibility in the `pegasus` Gradle plugin.
   - Minimum required Gradle version is now `1.0` (effectively backward-compatible).
   - Minimum suggested Gradle version is now `5.2.1`
+- Fix TimingKey Memory Leak
 
 ## [29.18.2] - 2021-04-28
 - Fix bug in generated fluent client APIs when typerefs are used as association key params
diff --git a/d2/src/main/java/com/linkedin/d2/balancer/clients/DynamicClient.java b/d2/src/main/java/com/linkedin/d2/balancer/clients/DynamicClient.java
index 8b7864808a..bc9467650e 100644
--- a/d2/src/main/java/com/linkedin/d2/balancer/clients/DynamicClient.java
+++ b/d2/src/main/java/com/linkedin/d2/balancer/clients/DynamicClient.java
@@ -157,6 +157,7 @@ public void shutdown(final Callback<None> callback)
 
       callback.onSuccess(None.none());
     });
+    TimingKey.unregisterKey(TIMING_KEY);
   }
 
   @Override
diff --git a/r2-core/src/main/java/com/linkedin/r2/filter/FilterChain.java b/r2-core/src/main/java/com/linkedin/r2/filter/FilterChain.java
index bd6273fb89..f2e9f142c3 100644
--- a/r2-core/src/main/java/com/linkedin/r2/filter/FilterChain.java
+++ b/r2-core/src/main/java/com/linkedin/r2/filter/FilterChain.java
@@ -23,7 +23,7 @@
 import com.linkedin.r2.message.rest.RestResponse;
 import com.linkedin.r2.message.stream.StreamRequest;
 import com.linkedin.r2.message.stream.StreamResponse;
-
+import java.util.List;
 import java.util.Map;
 
 /**
@@ -189,4 +189,14 @@ void onStreamResponse(StreamResponse res,
   void onStreamError(Exception ex,
                    RequestContext requestContext,
                    Map<String, String> wireAttrs);
+
+  /**
+   * Returns a copy of a list of RestFilters
+   */
+  List<RestFilter> getRestFilters();
+
+  /**
+   * Returns a copy of a list of StreamFilters
+   */
+  List<StreamFilter> getStreamFilters();
 }
diff --git a/r2-core/src/main/java/com/linkedin/r2/filter/FilterChainImpl.java b/r2-core/src/main/java/com/linkedin/r2/filter/FilterChainImpl.java
index dee5ff2ced..725f3193f7 100644
--- a/r2-core/src/main/java/com/linkedin/r2/filter/FilterChainImpl.java
+++ b/r2-core/src/main/java/com/linkedin/r2/filter/FilterChainImpl.java
@@ -78,6 +78,16 @@ public FilterChain addLast(StreamFilter filter)
     return new FilterChainImpl(_restFilters, doAddLast(_streamFilters, decorateStreamFilter(filter)));
   }
 
+  @Override
+  public List<RestFilter> getRestFilters() {
+    return new ArrayList<RestFilter>(_restFilters);
+  }
+
+  @Override
+  public List<StreamFilter> getStreamFilters() {
+    return new ArrayList<StreamFilter>(_streamFilters);
+  }
+
   private RestFilter decorateRestFilter(RestFilter filter)
   {
     return new TimedRestFilter(filter);
diff --git a/r2-core/src/main/java/com/linkedin/r2/filter/TimedRestFilter.java b/r2-core/src/main/java/com/linkedin/r2/filter/TimedRestFilter.java
index 0261b5a0f8..ee7cecfe1d 100644
--- a/r2-core/src/main/java/com/linkedin/r2/filter/TimedRestFilter.java
+++ b/r2-core/src/main/java/com/linkedin/r2/filter/TimedRestFilter.java
@@ -23,6 +23,8 @@
 import com.linkedin.r2.message.rest.RestRequest;
 import com.linkedin.r2.message.rest.RestResponse;
 import com.linkedin.r2.message.timing.TimingImportance;
+import java.util.Arrays;
+import java.util.List;
 import java.util.Map;
 
 
@@ -31,7 +33,7 @@
  *
  * @author Xialin Zhu
  */
-/* package private */ class TimedRestFilter implements RestFilter
+public class TimedRestFilter implements RestFilter
 {
   protected static final String ON_REQUEST_SUFFIX = "onRequest";
   protected static final String ON_RESPONSE_SUFFIX = "onResponse";
@@ -41,6 +43,7 @@
   private final TimingKey _onRequestTimingKey;
   private final TimingKey _onResponseTimingKey;
   private final TimingKey _onErrorTimingKey;
+  private boolean _shared;
 
   /**
    * Registers {@link TimingKey}s for {@link com.linkedin.r2.message.timing.TimingNameConstants#TIMED_REST_FILTER}.
@@ -61,6 +64,7 @@ public TimedRestFilter(RestFilter restFilter)
         _restFilter.getClass().getSimpleName(), TimingImportance.LOW);
     _onErrorTimingKey = TimingKey.registerNewKey(timingKeyPrefix + ON_ERROR_SUFFIX + timingKeyPostfix,
         _restFilter.getClass().getSimpleName(), TimingImportance.LOW);
+    _shared = false;
   }
 
   @Override
@@ -91,4 +95,16 @@ public void onRestError(Throwable ex,
     TimingContextUtil.markTiming(requestContext, _onErrorTimingKey);
     _restFilter.onRestError(ex, requestContext, wireAttrs, new TimedNextFilter<>(_onErrorTimingKey, nextFilter));
   }
+
+  public void setShared() {
+    _shared = true;
+  }
+
+  public void onShutdown() {
+    if (!_shared) {
+      TimingKey.unregisterKey(_onErrorTimingKey);
+      TimingKey.unregisterKey(_onRequestTimingKey);
+      TimingKey.unregisterKey(_onResponseTimingKey);
+    }
+  }
 }
diff --git a/r2-core/src/main/java/com/linkedin/r2/filter/TimedStreamFilter.java b/r2-core/src/main/java/com/linkedin/r2/filter/TimedStreamFilter.java
index c1759decac..ec6a29112b 100644
--- a/r2-core/src/main/java/com/linkedin/r2/filter/TimedStreamFilter.java
+++ b/r2-core/src/main/java/com/linkedin/r2/filter/TimedStreamFilter.java
@@ -34,12 +34,13 @@
  *
  * @author Xialin Zhu
  */
-/* package private */ class TimedStreamFilter implements StreamFilter
+public class TimedStreamFilter implements StreamFilter
 {
   private final StreamFilter _streamFilter;
   private final TimingKey _onRequestTimingKey;
   private final TimingKey _onResponseTimingKey;
   private final TimingKey _onErrorTimingKey;
+  private boolean _shared;
 
   /**
    * Registers {@link TimingKey}s for {@link com.linkedin.r2.message.timing.TimingNameConstants#TIMED_STREAM_FILTER}.
@@ -60,6 +61,7 @@ public TimedStreamFilter(StreamFilter streamFilter)
         filterClassName, TimingImportance.LOW);
     _onErrorTimingKey = TimingKey.registerNewKey(timingKeyPrefix + ON_ERROR_SUFFIX + timingKeyPostfix,
         filterClassName, TimingImportance.LOW);
+    _shared = false;
   }
 
   @Override
@@ -91,4 +93,16 @@ public void onStreamError(Throwable ex,
     TimingContextUtil.markTiming(requestContext, _onErrorTimingKey);
     _streamFilter.onStreamError(ex, requestContext, wireAttrs, new TimedNextFilter<>(_onErrorTimingKey, nextFilter));
   }
+
+  public void setShared() {
+    _shared = true;
+  }
+
+  public void onShutdown() {
+    if (!_shared) {
+      TimingKey.unregisterKey(_onErrorTimingKey);
+      TimingKey.unregisterKey(_onRequestTimingKey);
+      TimingKey.unregisterKey(_onResponseTimingKey);
+    }
+  }
 }
diff --git a/r2-core/src/main/java/com/linkedin/r2/filter/transport/FilterChainClient.java b/r2-core/src/main/java/com/linkedin/r2/filter/transport/FilterChainClient.java
index 11e4e15840..134200be56 100644
--- a/r2-core/src/main/java/com/linkedin/r2/filter/transport/FilterChainClient.java
+++ b/r2-core/src/main/java/com/linkedin/r2/filter/transport/FilterChainClient.java
@@ -17,10 +17,13 @@
 /* $Id$ */
 package com.linkedin.r2.filter.transport;
 
-
 import com.linkedin.common.callback.Callback;
 import com.linkedin.common.util.None;
 import com.linkedin.r2.filter.FilterChain;
+import com.linkedin.r2.filter.TimedRestFilter;
+import com.linkedin.r2.filter.TimedStreamFilter;
+import com.linkedin.r2.filter.message.rest.RestFilter;
+import com.linkedin.r2.filter.message.stream.StreamFilter;
 import com.linkedin.r2.message.RequestContext;
 import com.linkedin.r2.message.Response;
 import com.linkedin.r2.message.rest.RestRequest;
@@ -29,12 +32,15 @@
 import com.linkedin.r2.message.stream.StreamResponse;
 import com.linkedin.r2.message.timing.FrameworkTimingKeys;
 import com.linkedin.r2.message.timing.TimingContextUtil;
+import com.linkedin.r2.message.timing.TimingKey;
 import com.linkedin.r2.transport.common.bridge.client.TransportClient;
 import com.linkedin.r2.transport.common.bridge.common.TransportCallback;
-
 import com.linkedin.r2.transport.common.bridge.common.TransportResponse;
+import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 
+
 /**
  * {@link TransportClient} adapter which composes a {@link TransportClient}
  * and a {@link FilterChain}.
@@ -94,6 +100,12 @@ public void streamRequest(StreamRequest request,
   public void shutdown(Callback<None> callback)
   {
     _client.shutdown(callback);
+
+    _filters.getStreamFilters().stream().filter(TimedStreamFilter.class::isInstance)
+      .map(TimedStreamFilter.class::cast).forEach(TimedStreamFilter::onShutdown);
+
+    _filters.getRestFilters().stream().filter(TimedRestFilter.class::isInstance)
+      .map(TimedRestFilter.class::cast).forEach(TimedRestFilter::onShutdown);
   }
 
   /**
diff --git a/r2-core/src/main/java/com/linkedin/r2/message/timing/TimingKey.java b/r2-core/src/main/java/com/linkedin/r2/message/timing/TimingKey.java
index 8d551af59f..7012121e83 100644
--- a/r2-core/src/main/java/com/linkedin/r2/message/timing/TimingKey.java
+++ b/r2-core/src/main/java/com/linkedin/r2/message/timing/TimingKey.java
@@ -17,9 +17,12 @@
 package com.linkedin.r2.message.timing;
 
 import java.util.Map;
+import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentHashMap;
 
 import com.linkedin.r2.message.RequestContext;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 
 /**
@@ -32,6 +35,7 @@
 public class TimingKey
 {
   private static final Map<String, TimingKey> _pool = new ConcurrentHashMap<>();
+  private static final ExecutorService _unregisterExecutor = Executors.newFixedThreadPool(1);
 
   private final String _name;
   private final String _type;
@@ -130,4 +134,26 @@ public static TimingKey registerNewKey(String uniqueName, String type, TimingImp
   {
     return registerNewKey(new TimingKey(uniqueName, type, timingImportance));
   }
+
+  /**
+   * Unregister a TimingKey to reclaim the memory
+   *
+   */
+  public static void unregisterKey(TimingKey key)
+  {
+    _unregisterExecutor.submit(new Callable<Void>() {
+      public Void call() throws Exception {
+        _pool.remove(key.getName());
+        return null;
+      }
+    });
+  }
+
+  /**
+   * Return how many registered keys, for testing purpose.
+   */
+  public static int getCount() {
+    return _pool.size();
+  }
+
 }
diff --git a/r2-netty/src/main/java/com/linkedin/r2/netty/client/HttpNettyClient.java b/r2-netty/src/main/java/com/linkedin/r2/netty/client/HttpNettyClient.java
index d458a2f1a1..e9d0ac9fac 100644
--- a/r2-netty/src/main/java/com/linkedin/r2/netty/client/HttpNettyClient.java
+++ b/r2-netty/src/main/java/com/linkedin/r2/netty/client/HttpNettyClient.java
@@ -246,6 +246,7 @@ public void onSuccess(None result)
     {
       callback.onError(new IllegalStateException("Shutdown has already been requested."));
     }
+    TimingKey.unregisterKey(TIMING_KEY);
   }
 
   private void sendStreamRequestAsRestRequest(StreamRequest request, RequestContext requestContext,
diff --git a/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/HttpClientFactory.java b/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/HttpClientFactory.java
index 2be59979f3..6b1de01551 100644
--- a/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/HttpClientFactory.java
+++ b/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/HttpClientFactory.java
@@ -26,6 +26,8 @@
 import com.linkedin.r2.filter.CompressionConfig;
 import com.linkedin.r2.filter.FilterChain;
 import com.linkedin.r2.filter.FilterChains;
+import com.linkedin.r2.filter.TimedRestFilter;
+import com.linkedin.r2.filter.TimedStreamFilter;
 import com.linkedin.r2.filter.compression.ClientCompressionFilter;
 import com.linkedin.r2.filter.compression.ClientCompressionHelper;
 import com.linkedin.r2.filter.compression.ClientStreamCompressionFilter;
@@ -685,6 +687,11 @@ private HttpClientFactory(FilterChain filters,
     {
       _channelPoolManagerFactory = new ConnectionSharingChannelPoolManagerFactory(_channelPoolManagerFactory);
     }
+
+    _filters.getStreamFilters().stream().filter(TimedStreamFilter.class::isInstance)
+      .map(TimedStreamFilter.class::cast).forEach(TimedStreamFilter::setShared);
+    _filters.getRestFilters().stream().filter(TimedRestFilter.class::isInstance)
+        .map(TimedRestFilter.class::cast).forEach(TimedRestFilter::setShared);
   }
 
   public static class Builder
@@ -958,7 +965,6 @@ public TransportClient getClient(Map<String, ? extends Object> properties)
     properties = new HashMap<String,Object>(properties);
     sslContext = coerceAndRemoveFromMap(HTTP_SSL_CONTEXT, properties, SSLContext.class);
     sslParameters = coerceAndRemoveFromMap(HTTP_SSL_PARAMS, properties, SSLParameters.class);
-
     return getClient(properties, sslContext, sslParameters);
   }
 
diff --git a/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/common/AbstractNettyClient.java b/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/common/AbstractNettyClient.java
index d08dbc1e8a..4db1b81ee9 100644
--- a/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/common/AbstractNettyClient.java
+++ b/r2-netty/src/main/java/com/linkedin/r2/transport/http/client/common/AbstractNettyClient.java
@@ -284,6 +284,7 @@ public void onSuccess(None result)
           _shutdownTimeout);
       _jmxManager.onProviderShutdown(_channelPoolManager);
       _jmxManager.onProviderShutdown(_sslChannelPoolManager);
+      TimingKey.unregisterKey(TIMING_KEY);
     }
     else
     {
diff --git a/r2-netty/src/test/java/com/linkedin/r2/transport/http/client/TestHttpClientFactory.java b/r2-netty/src/test/java/com/linkedin/r2/transport/http/client/TestHttpClientFactory.java
index 136b599c9d..9ca82c882b 100644
--- a/r2-netty/src/test/java/com/linkedin/r2/transport/http/client/TestHttpClientFactory.java
+++ b/r2-netty/src/test/java/com/linkedin/r2/transport/http/client/TestHttpClientFactory.java
@@ -27,6 +27,7 @@
 import com.linkedin.r2.message.rest.RestRequest;
 import com.linkedin.r2.message.rest.RestRequestBuilder;
 import com.linkedin.r2.message.rest.RestResponse;
+import com.linkedin.r2.message.timing.TimingKey;
 import com.linkedin.r2.testutils.server.HttpServerBuilder;
 import com.linkedin.r2.transport.common.Client;
 import com.linkedin.r2.transport.common.bridge.client.TransportClient;
@@ -93,13 +94,17 @@ public void testSuccessfulRequest(boolean restOverStream, String protocolVersion
     {
       server.start();
       List<Client> clients = new ArrayList<>();
+
+      int savedTimingKeyCount = TimingKey.getCount();
       for (int i = 0; i < 100; i++)
       {
         HashMap<String, String> properties = new HashMap<>();
         properties.put(HttpClientFactory.HTTP_PROTOCOL_VERSION, protocolVersion);
         clients.add(new TransportClientAdapter(factory.getClient(properties), restOverStream));
       }
-
+      int addedTimingKeyCount = TimingKey.getCount() - savedTimingKeyCount;
+      // In current implementation, one client can have around 30 TimingKeys by default.
+      Assert.assertTrue(addedTimingKeyCount >= 30 * clients.size());
       for (Client c : clients)
       {
         RestRequest r = new RestRequestBuilder(new URI(URI)).build();
@@ -107,6 +112,7 @@ public void testSuccessfulRequest(boolean restOverStream, String protocolVersion
       }
       Assert.assertEquals(httpServerStatsProvider.requestCount(), expectedRequests);
 
+      savedTimingKeyCount = TimingKey.getCount();
       for (Client c : clients)
       {
         FutureCallback<None> callback = new FutureCallback<>();
@@ -117,6 +123,8 @@ public void testSuccessfulRequest(boolean restOverStream, String protocolVersion
       FutureCallback<None> factoryShutdown = new FutureCallback<>();
       factory.shutdown(factoryShutdown);
       factoryShutdown.get(30, TimeUnit.SECONDS);
+      int removedTimingKeyCount = savedTimingKeyCount - TimingKey.getCount();
+      Assert.assertEquals(addedTimingKeyCount, removedTimingKeyCount);
     }
     finally
     {