Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/12612#discussion_r60753108
--- Diff: core/src/main/scala/org/apache/spark/NewAccumulator.scala ---
@@ -0,0 +1,299 @@
+/*
+ * 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
+
+import java.{lang => jl}
+import java.io.{ObjectInputStream, ObjectOutputStream}
+import java.util.concurrent.atomic.AtomicLong
+import javax.annotation.concurrent.GuardedBy
+
+import org.apache.spark.scheduler.AccumulableInfo
+import org.apache.spark.util.Utils
+
+
+private[spark] case class AccumulatorMetadata(
+ id: Long,
+ name: Option[String],
+ countFailedValues: Boolean) extends Serializable
+
+
+abstract class NewAccumulator[IN, OUT] extends Serializable {
+ private[spark] var metadata: AccumulatorMetadata = _
+
+ private[spark] def register(
+ sc: SparkContext,
+ id: Long = AccumulatorContext.newId(),
+ name: Option[String] = None,
+ countFailedValues: Boolean = false): Unit = {
+ if (this.metadata != null) {
+ throw new IllegalStateException("Cannot register an Accumulator
twice.")
+ }
+ this.metadata = AccumulatorMetadata(id, name, countFailedValues)
+ AccumulatorContext.register(this)
+ sc.cleaner.foreach(_.registerAccumulatorForCleanup(this))
+ }
+
+ private[spark] def assertRegistered(): Unit = {
+ if (metadata == null) {
+ throw new IllegalStateException("Accumulator is not registered yet")
+ }
+ }
+
+ def id: Long = {
+ assertRegistered()
+ metadata.id
+ }
+
+ def initialize(): Unit = {}
+
+ def add(v: IN): Unit
+
+ def +=(v: IN): Unit = add(v)
+
+ def merge(other: NewAccumulator[IN, OUT]): Unit
+
+ def ++=(other: NewAccumulator[IN, OUT]): Unit = merge(other)
+
+ def value: OUT
+
+ private[spark] def toInfo(update: Option[Any], value: Option[Any]):
AccumulableInfo = {
+ assertRegistered()
+ val isInternal =
metadata.name.exists(_.startsWith(InternalAccumulator.METRICS_PREFIX))
+ new AccumulableInfo(
+ metadata.id, metadata.name, update, value, isInternal,
metadata.countFailedValues)
+ }
+
+ // Called by Java when serializing an object
+ private def writeObject(out: ObjectOutputStream): Unit =
Utils.tryOrIOException {
+ assertRegistered()
+ out.defaultWriteObject()
+ }
+
+ // Called by Java when deserializing an object
+ private def readObject(in: ObjectInputStream): Unit =
Utils.tryOrIOException {
+ in.defaultReadObject()
+ initialize()
+
+ // Automatically register the accumulator when it is deserialized with
the task closure.
+ // This is for external accumulators and internal ones that do not
represent task level
+ // metrics, e.g. internal SQL metrics, which are per-operator.
+ val taskContext = TaskContext.get()
+ if (taskContext != null) {
+ taskContext.registerAccumulator(this)
+ }
+ }
+}
+
+object AccumulatorContext {
+
+ /**
+ * This global map holds the original accumulator objects that are
created on the driver.
+ * It keeps weak references to these objects so that accumulators can be
garbage-collected
+ * once the RDDs and user-code that reference them are cleaned up.
+ * TODO: Don't use a global map; these should be tied to a SparkContext
(SPARK-13051).
+ */
+ @GuardedBy("AccumulatorContext")
+ private val originals = new java.util.HashMap[Long,
jl.ref.WeakReference[NewAccumulator[_, _]]]
+
+ private[this] val nextId = new AtomicLong(0L)
+
+ /**
+ * Return a globally unique ID for a new [[NewAccumulator]].
+ * Note: Once you copy the [[NewAccumulator]] the ID is no longer unique.
+ */
+ def newId(): Long = nextId.getAndIncrement
+
+ /**
+ * Register an [[NewAccumulator]] created on the driver such that it can
be used on the executors.
+ *
+ * All accumulators registered here can later be used as a container for
accumulating partial
+ * values across multiple tasks. This is what
[[org.apache.spark.scheduler.DAGScheduler]] does.
+ * Note: if an accumulator is registered here, it should also be
registered with the active
+ * context cleaner for cleanup so as to avoid memory leaks.
+ *
+ * If an [[NewAccumulator]] with the same ID was already registered,
this does nothing instead
+ * of overwriting it. This happens when we copy accumulators, e.g. when
we reconstruct
+ * [[org.apache.spark.executor.TaskMetrics]] from accumulator updates.
+ */
+ def register(a: NewAccumulator[_, _]): Unit = synchronized {
+ if (!originals.containsKey(a.id)) {
+ originals.put(a.id, new jl.ref.WeakReference[NewAccumulator[_,
_]](a))
+ }
+ }
+
+ /**
+ * Unregister the [[NewAccumulator]] with the given ID, if any.
+ */
+ def remove(id: Long): Unit = synchronized {
+ originals.remove(id)
+ }
+
+ /**
+ * Return the [[NewAccumulator]] registered with the given ID, if any.
+ */
+ def get(id: Long): Option[NewAccumulator[_, _]] = synchronized {
+ Option(originals.get(id)).map { ref =>
+ // Since we are storing weak references, we must check whether the
underlying data is valid.
+ val acc = ref.get
+ if (acc eq null) {
+ throw new IllegalAccessError(s"Attempted to access garbage
collected accumulator $id")
+ }
+ acc
+ }
+ }
+
+ /**
+ * Clear all registered [[NewAccumulator]]s. For testing only.
+ */
+ def clear(): Unit = synchronized {
+ originals.clear()
+ }
+}
+
+
+class IntAccumulator extends NewAccumulator[jl.Integer, jl.Integer] {
+ @transient private[this] var _sum = 0
+
+ override def add(v: jl.Integer): Unit = {
+ _sum += v
+ }
+
+ override def merge(other: NewAccumulator[jl.Integer, jl.Integer]): Unit
= other match {
+ case o: IntAccumulator => _sum += o.sum
+ case _ => throw new UnsupportedOperationException(
+ s"Cannot merge ${this.getClass.getName} with
${other.getClass.getName}")
+ }
+
+ override def value: jl.Integer = _sum
+
+ def sum: Int = _sum
+
+ def setValue(newValue: Int): Unit = _sum = newValue
+}
+
+
+class LongAccumulator extends NewAccumulator[jl.Long, jl.Long] {
+ @transient private[this] var _sum = 0L
+
+ override def add(v: jl.Long): Unit = {
+ _sum += v
+ }
+
+ override def merge(other: NewAccumulator[jl.Long, jl.Long]): Unit =
other match {
+ case o: LongAccumulator => _sum += o.sum
+ case _ => throw new UnsupportedOperationException(
+ s"Cannot merge ${this.getClass.getName} with
${other.getClass.getName}")
+ }
+
+ override def value: jl.Long = _sum
+
+ def sum: Long = _sum
+
+ def setValue(newValue: Long): Unit = _sum = newValue
+}
+
+
+class DoubleAccumulator extends NewAccumulator[jl.Double, jl.Double] {
+ @transient private[this] var _sum = 0.0
+
+ override def add(v: jl.Double): Unit = {
+ _sum += v
+ }
+
+ override def merge(other: NewAccumulator[jl.Double, jl.Double]): Unit =
other match {
+ case o: DoubleAccumulator => _sum += o.sum
+ case _ => throw new UnsupportedOperationException(
+ s"Cannot merge ${this.getClass.getName} with
${other.getClass.getName}")
+ }
+
+ override def value: jl.Double = _sum
+
+ def sum: Double = _sum
+
+ def setValue(newValue: Double): Unit = _sum = newValue
+}
+
+
+class AverageAccumulator extends NewAccumulator[jl.Double, jl.Double] {
--- End diff --
One difference from the previous API: we can't have a general `setValue`
method, as it needs the intermedia type which is not exposed by the new API.
For example, `AverageAccumulator` doesn't have `setValue`
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
