[client] add exception logging for client request errors (linkedin#1887)

Author: pthirun

clients/venice-thin-client/src/main/java/com/linkedin/venice/client/store/StatTrackingStoreClient.java

@@ -17,6 +17,7 @@
 import com.linkedin.venice.stats.ClientType;
 import com.linkedin.venice.stats.TehutiUtils;
 import com.linkedin.venice.utils.LatencyUtils;
+import com.linkedin.venice.utils.RedundantExceptionFilter;
 import com.linkedin.venice.utils.concurrent.VeniceConcurrentHashMap;
 import io.tehuti.metrics.MetricsRepository;
 import java.util.Map;
@@ -38,6 +39,7 @@
  */
 public class StatTrackingStoreClient<K, V> extends DelegatingStoreClient<K, V> {
   private static final Logger LOGGER = LogManager.getLogger(StatTrackingStoreClient.class);
+  private static final RedundantExceptionFilter EXCEPTION_FILTER = new RedundantExceptionFilter();
 
   private static final String STAT_VENICE_CLIENT_NAME = "venice_client";
   private static final String STAT_SCHEMA_READER = "schema_reader";
@@ -246,6 +248,7 @@ public void compute(
 
   private static void handleUnhealthyRequest(ClientStats clientStats, Throwable throwable, double latency) {
     int httpStatus = getUnhealthyRequestHttpStatus(throwable);
+    logException(clientStats.getName(), throwable);
     clientStats.emitUnhealthyRequestMetrics(latency, httpStatus);
     if (throwable instanceof VeniceClientHttpException) {
       clientStats.recordHttpRequest(httpStatus);
@@ -268,6 +271,12 @@ private static void handleMetricTrackingForStreamingCallback(
     clientStats.recordSuccessDuplicateRequestKeyCount(duplicateEntryCnt);
   }
 
+  private static void logException(String storeName, Throwable throwable) {
+    if (!EXCEPTION_FILTER.isRedundantException(storeName, throwable)) {
+      LOGGER.error("Unhealthy request with error: ", throwable);
+    }
+  }
+
   @Override
   public ComputeRequestBuilder<K> compute() throws VeniceClientException {
     /**