ForVic commented on code in PR #50230:
URL: https://github.com/apache/spark/pull/50230#discussion_r2302298138
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core/src/main/scala/org/apache/spark/internal/config/package.scala:
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@@ -1650,6 +1650,21 @@ package object config {
s"The buffer size must be greater than 0 and less than or equal to
${Int.MaxValue}.")
.createWithDefault(4096)
+ private[spark] val SHUFFLE_ORDER_INDEPENDENT_CHECKSUM_ENABLED =
+ ConfigBuilder("spark.shuffle.orderIndependentChecksum.enabled")
+ .doc("Whether to calculate order independent checksum for the shuffle
data or not. If " +
+ "enabled, Spark will calculate a checksum that is independent of the
input row order for " +
+ "each mapper and returns the checksums from executors to driver.
Different from the above" +
Review Comment:
nit: need space at end of string on this line
##########
core/src/main/scala/org/apache/spark/internal/config/package.scala:
##########
@@ -1650,6 +1650,21 @@ package object config {
s"The buffer size must be greater than 0 and less than or equal to
${Int.MaxValue}.")
.createWithDefault(4096)
+ private[spark] val SHUFFLE_ORDER_INDEPENDENT_CHECKSUM_ENABLED =
+ ConfigBuilder("spark.shuffle.orderIndependentChecksum.enabled")
+ .doc("Whether to calculate order independent checksum for the shuffle
data or not. If " +
+ "enabled, Spark will calculate a checksum that is independent of the
input row order for " +
+ "each mapper and returns the checksums from executors to driver.
Different from the above" +
+ "checksum, the order independent remains the same even if the shuffle
row order changes. " +
+ "While the above checksum is sensitive to shuffle data ordering to
detect file " +
Review Comment:
what is "above checksum" referring to?
##########
core/src/main/java/org/apache/spark/shuffle/checksum/RowBasedChecksum.scala:
##########
@@ -0,0 +1,108 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.shuffle.checksum
+
+import java.io.ObjectOutputStream
+import java.util.zip.Checksum
+
+import scala.util.control.NonFatal
+
+import org.apache.spark.internal.Logging
+import org.apache.spark.network.shuffle.checksum.ShuffleChecksumHelper
+import org.apache.spark.util.ExposedBufferByteArrayOutputStream
+
+/**
+ * A class for computing checksum for input (key, value) pairs. The checksum
is independent of
+ * the order of the input (key, value) pairs. It is done by computing a
checksum for each row
+ * first, and then computing the XOR for all the row checksums.
+ */
+abstract class RowBasedChecksum() extends Serializable with Logging {
+ private var hasError: Boolean = false
+ private var checksumValue: Long = 0
+ /** Returns the checksum value computed. Tt returns the default checksum
value (0) if there
+ * are any errors encountered during the checksum computation.
+ */
+ def getValue: Long = {
+ if (!hasError) checksumValue else 0
+ }
+
+ /** Updates the row-based checksum with the given (key, value) pair */
+ def update(key: Any, value: Any): Unit = {
+ if (!hasError) {
+ try {
+ val rowChecksumValue = calculateRowChecksum(key, value)
+ checksumValue = checksumValue ^ rowChecksumValue
+ } catch {
+ case NonFatal(e) =>
+ logError("Checksum computation encountered error: ", e)
+ hasError = true
+ }
+ }
+ }
+
+ /** Computes and returns the checksum value for the given (key, value) pair
*/
+ protected def calculateRowChecksum(key: Any, value: Any): Long
+}
+
+/**
+ * A Concrete implementation of RowBasedChecksum. The checksum for each row is
+ * computed by first converting the (key, value) pair to byte array using
OutputStreams,
+ * and then computing the checksum for the byte array.
+ * Note that this checksum computation is very expensive, and it is used only
in tests
+ * in the core component. A much cheaper implementation of RowBasedChecksum is
in
+ * UnsafeRowChecksum.
+ *
+ * @param checksumAlgorithm the algorithm used for computing checksum.
+ */
+class OutputStreamRowBasedChecksum(checksumAlgorithm: String)
Review Comment:
just a question: I don't see this used anywhere except in tests, why not
have it in `core/src/test` instead?
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core/src/main/scala/org/apache/spark/scheduler/MapStatus.scala:
##########
@@ -58,6 +58,12 @@ private[spark] sealed trait MapStatus extends
ShuffleOutputStatus {
* partitionId of the task or taskContext.taskAttemptId is used.
*/
def mapId: Long
+
+ /**
+ * The checksum value of this shuffle map task, which can be used to
evaluate whether the
+ * output data have changed across different map task retries.
Review Comment:
`output data have` -> `output data has`
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