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wenchen pushed a commit to branch branch-3.3
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The following commit(s) were added to refs/heads/branch-3.3 by this push:
new 0f234d9997b [SPARK-40932][CORE] Fix issue messages for allGather are
overridden
0f234d9997b is described below
commit 0f234d9997bb6cb6591991f9e57db4c79d9d0bb9
Author: Bobby Wang <wbo4...@gmail.com>
AuthorDate: Fri Oct 28 21:06:49 2022 +0800
[SPARK-40932][CORE] Fix issue messages for allGather are overridden
### What changes were proposed in this pull request?
The messages returned by allGather may be overridden by the following
barrier APIs, eg,
``` scala
val messages: Array[String] = context.allGather("ABC")
context.barrier()
```
the `messages` may be like Array("", ""), but we're expecting Array("ABC",
"ABC")
The root cause of this issue is the [messages got by
allGather](https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/BarrierTaskContext.scala#L102)
pointing to the [original
message](https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/BarrierCoordinator.scala#L107)
in the local mode. So when the following barrier APIs changed the messages,
then the allGather message will be changed accordingly.
Finally, users can't get the correct result.
This PR fixed this issue by sending back the cloned messages.
### Why are the changes needed?
The bug mentioned in this description may block some external SPARK ML
libraries which heavily depend on the spark barrier API to do some
synchronization. If the barrier mechanism can't guarantee the correctness of
the barrier APIs, it will be a disaster for external SPARK ML libraries.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
I added a unit test, with this PR, the unit test can pass
Closes #38410 from wbo4958/allgather-issue.
Authored-by: Bobby Wang <wbo4...@gmail.com>
Signed-off-by: Wenchen Fan <wenc...@databricks.com>
(cherry picked from commit 0b892a543f9ea913f961eea95a4e45f1231b9a57)
Signed-off-by: Wenchen Fan <wenc...@databricks.com>
---
.../org/apache/spark/BarrierCoordinator.scala | 2 +-
.../spark/scheduler/BarrierTaskContextSuite.scala | 23 ++++++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/core/src/main/scala/org/apache/spark/BarrierCoordinator.scala
b/core/src/main/scala/org/apache/spark/BarrierCoordinator.scala
index 04faf7f87cf..8ffccdf664b 100644
--- a/core/src/main/scala/org/apache/spark/BarrierCoordinator.scala
+++ b/core/src/main/scala/org/apache/spark/BarrierCoordinator.scala
@@ -176,7 +176,7 @@ private[spark] class BarrierCoordinator(
logInfo(s"Barrier sync epoch $barrierEpoch from $barrierId received
update from Task " +
s"$taskId, current progress: ${requesters.size}/$numTasks.")
if (requesters.size == numTasks) {
- requesters.foreach(_.reply(messages))
+ requesters.foreach(_.reply(messages.clone()))
// Finished current barrier() call successfully, clean up
ContextBarrierState and
// increase the barrier epoch.
logInfo(s"Barrier sync epoch $barrierEpoch from $barrierId received
all updates from " +
diff --git
a/core/src/test/scala/org/apache/spark/scheduler/BarrierTaskContextSuite.scala
b/core/src/test/scala/org/apache/spark/scheduler/BarrierTaskContextSuite.scala
index 4f97003e2ed..26cd5374fa0 100644
---
a/core/src/test/scala/org/apache/spark/scheduler/BarrierTaskContextSuite.scala
+++
b/core/src/test/scala/org/apache/spark/scheduler/BarrierTaskContextSuite.scala
@@ -367,4 +367,27 @@ class BarrierTaskContextSuite extends SparkFunSuite with
LocalSparkContext with
// double check we kill task success
assert(System.currentTimeMillis() - startTime < 5000)
}
+
+ test("SPARK-40932, messages of allGather should not been overridden " +
+ "by the following barrier APIs") {
+
+ sc = new SparkContext(new
SparkConf().setAppName("test").setMaster("local[2]"))
+ sc.setLogLevel("INFO")
+ val rdd = sc.makeRDD(1 to 10, 2)
+ val rdd2 = rdd.barrier().mapPartitions { it =>
+ val context = BarrierTaskContext.get()
+ // Sleep for a random time before global sync.
+ Thread.sleep(Random.nextInt(1000))
+ // Pass partitionId message in
+ val message: String = context.partitionId().toString
+ val messages: Array[String] = context.allGather(message)
+ context.barrier()
+ Iterator.single(messages.toList)
+ }
+ val messages = rdd2.collect()
+ // All the task partitionIds are shared across all tasks
+ assert(messages.length === 2)
+ assert(messages.forall(_ == List("0", "1")))
+ }
+
}
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