srowen commented on a change in pull request #23896: [SPARK-26977][CORE] Fix
warn against subclassing scala.App
URL: https://github.com/apache/spark/pull/23896#discussion_r260343343
##########
File path: core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala
##########
@@ -828,9 +828,12 @@ private[spark] class SparkSubmit extends Logging {
val app: SparkApplication = if
(classOf[SparkApplication].isAssignableFrom(mainClass)) {
mainClass.newInstance().asInstanceOf[SparkApplication]
} else {
- // SPARK-4170
- if (classOf[scala.App].isAssignableFrom(mainClass)) {
- logWarning("Subclasses of scala.App may not work correctly. Use a
main() method instead.")
+ // SPARK-4170, SPARK-26977
+ Try {
+ if
(classOf[scala.App].isAssignableFrom(Utils.classForName(s"$childMainClass$$")))
{
+ logWarning("Subclasses of scala.App may not work correctly. " +
+ "Use a main() method instead.")
+ }
Review comment:
Oh nevermind me, I think the way this displays just made it look like the
brace was misaligned.
If the new check throws ClassNotFoundException, then that's fine, you just
do nothing. It doesn't match the condition we're trying to detect.
I think I'm still confused from the discussion at
https://github.com/apache/spark/pull/3497#pullrequestreview-205672379
If I specify a main class "com.foo.MyApp" and `class com.foo.MyApp exends
scala.App`, then there will be a class of that name in the bytecode that
extends `scala.App`, right? It can have static methods, and unless this whole
thing just never worked, it has a main() method, that we call -- Scala makes a
synthetic method that forwards or whatever.
I understand `object` is a potentially different case but don't you just
need to look for `com.foo.MyApp$`? I wasn't getting the dependence on
`childMainClass` here; that seems like a Scala implementation detail that's
unnecessary to look for.
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
With regards,
Apache Git Services
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
