Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/14467#discussion_r75271949
--- Diff: core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
---
@@ -889,21 +892,42 @@ private class PythonAccumulatorParam(@transient
private val serverHost: String,
socket
}
- override def zero(value: JList[Array[Byte]]): JList[Array[Byte]] = new
JArrayList
+ override def reset(): Unit = {
+ this._acc = Collections.synchronizedList(new JArrayList[Array[Byte]])
+ }
+
+ override def isZero: Boolean = {
+ this._acc.isEmpty
+ }
+
+ override def copyAndReset(): PythonAccumulatorV2 = new
PythonAccumulatorV2(serverHost, serverPort)
+
+ override def copy(): PythonAccumulatorV2 = {
+ val newAcc = new PythonAccumulatorV2(serverHost, serverPort)
+ newAcc._acc.addAll(this._acc)
+ newAcc
+ }
+
+ // This happens on the worker node, where we just want to remember all
the updates
+ override def add(val2: JList[Array[Byte]]): Unit = {
+ _acc.addAll(val2)
+ }
+
- override def addInPlace(val1: JList[Array[Byte]], val2:
JList[Array[Byte]])
- : JList[Array[Byte]] = synchronized {
+ override def merge(other: AccumulatorV2[JList[Array[Byte]],
JList[Array[Byte]]]): Unit = {
+ val otherPythonAccumulator = other.asInstanceOf[PythonAccumulatorV2]
+ // This conditional isn't strictly speaking needed - merging only
currently happens on the
+ // driver program - but that isn't gauranteed so incase this changes.
if (serverHost == null) {
- // This happens on the worker node, where we just want to remember
all the updates
- val1.addAll(val2)
- val1
+ // We are on the worker
+ add(otherPythonAccumulator._acc)
} else {
// This happens on the master, where we pass the updates to Python
through a socket
val socket = openSocket()
val in = socket.getInputStream
val out = new DataOutputStream(new
BufferedOutputStream(socket.getOutputStream, bufferSize))
- out.writeInt(val2.size)
- for (array <- val2.asScala) {
+ out.writeInt(otherPythonAccumulator._acc.size)
--- End diff --
I see, I'm wondering about the value of future-proofing this with more
consistent synchronization, vs the downside (code complexity, performance). It
doesn't make the code more complex, and if this is really only accessed by a
single thread, the lock overhead is virtually 0 in this context. Is it better
to just synchronize for future correctness?
---
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]
