[GitHub] [spark] juliuszsompolski commented on a diff in pull request #41829: [SPARK-44275][CONNECT] Add configurable retry mechanism to Scala Spark Connect

["juliuszsompolski (via GitHub)" <gi...@apache.org>]

juliuszsompolski commented on code in PR #41829:
URL: https://github.com/apache/spark/pull/41829#discussion_r1251818998


##########
connector/connect/client/jvm/src/main/scala/org/apache/spark/sql/connect/client/SparkConnectClient.scala:
##########
@@ -79,7 +107,11 @@ private[sql] class SparkConnectClient(
       .setSessionId(sessionId)
       .setClientType(userAgent)
       .build()
-    stub.executePlan(request)
+    retry {
+      val result = stub.executePlan(request)
+      result.hasNext // moves evaluation of BlockingResponseStream to SparkConnectClient

Review Comment:
   could you elaborate on why this is needed? I believe this `.hasNext` can block for quite a while until the first response comes back on the stream.



##########
connector/connect/client/jvm/src/main/scala/org/apache/spark/sql/connect/client/SparkConnectClient.scala:
##########
@@ -564,4 +606,33 @@ object SparkConnectClient {
       }
     }
   }
+
+  private[client] def retryException(e: Throwable): Boolean = {
+    if (e.isInstanceOf[StatusRuntimeException]) {
+      e.asInstanceOf[StatusRuntimeException].getStatus().getCode() == Status.Code.UNAVAILABLE
+    } else {
+      false
+    }
+  }
+
+  /**
+   * [[RetryParameters]] configure the retry mechanism in [[SparkConnectClient]]
+   *
+   * @param max_retries
+   *   Maximum number of retries.
+   * @param initial_backoff
+   *   Start value of the exponential backoff (ms).
+   * @param max_backoff
+   *   Maximal value of the exponential backoff (ms).
+   * @param backoff_multiplier
+   *   Multiplicative base of the exponential backoff.
+   * @param should_retry
+   *   Function that determines whether a retry is to be performed in the event of an error.
+   */
+  private[client] case class RetryParameters(
+      max_retries: Int = 15,

Review Comment:
   use camelCase instead of snake_case for parameters.



##########
connector/connect/client/jvm/src/main/scala/org/apache/spark/sql/connect/client/SparkConnectClient.scala:
##########
@@ -564,4 +606,33 @@ object SparkConnectClient {
       }
     }
   }
+
+  private[client] def retryException(e: Throwable): Boolean = {
+    if (e.isInstanceOf[StatusRuntimeException]) {
+      e.asInstanceOf[StatusRuntimeException].getStatus().getCode() == Status.Code.UNAVAILABLE
+    } else {
+      false
+    }
+  }
+
+  /**
+   * [[RetryParameters]] configure the retry mechanism in [[SparkConnectClient]]
+   *
+   * @param max_retries
+   *   Maximum number of retries.
+   * @param initial_backoff
+   *   Start value of the exponential backoff (ms).
+   * @param max_backoff
+   *   Maximal value of the exponential backoff (ms).
+   * @param backoff_multiplier
+   *   Multiplicative base of the exponential backoff.
+   * @param should_retry
+   *   Function that determines whether a retry is to be performed in the event of an error.

Review Comment:
   specifying this configuration and defining which exceptions should be retries is a followup?



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