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https://issues.apache.org/jira/browse/SPARK-26839?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dongjoon Hyun updated SPARK-26839:
----------------------------------
Description:
Java 9+ changed how ClassLoaders work. The two most salient points:
The boot classloader no longer 'sees' the platform classes. A new 'platform
classloader' does and should be the parent of new ClassLoaders
The system classloader is no longer a URLClassLoader, so we can't get the URLs
of JARs in its classpath
was:
This might be very specific to my fork & a kind of weird system setup I'm
working on, I haven't completely confirmed yet, but I wanted to report it
anyway in case anybody else sees this.
When I try to do anything which touches the metastore on java11, I immediately
get errors from IsolatedClientLoader that it can't load anything in java.sql.
eg.
{noformat}
scala> spark.sql("show tables").show()
java.lang.ClassNotFoundException: java.lang.NoClassDefFoundError:
java/sql/SQLTransientException when creating Hive client using classpath:
file:/home/systest/jdk-11.0.2/, ...
...
Caused by: java.lang.ClassNotFoundException: java.sql.SQLTransientException
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:471)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
at
org.apache.spark.sql.hive.client.IsolatedClientLoader$$anon$1.doLoadClass(IsolatedClientLoader.scala:230)
at
org.apache.spark.sql.hive.client.IsolatedClientLoader$$anon$1.loadClass(IsolatedClientLoader.scala:219)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
{noformat}
After a bit of debugging, I also discovered that the {{rootClassLoader}} is
{{null}} in {{IsolatedClientLoader}}. I think this would work if either
{{rootClassLoader}} could load those classes, or if {{isShared()}} was changed
to allow any class starting with "java." (I'm not sure why it only allows
"java.lang" and "java.net" currently.)
> Work around classloader changes in Java 9 for Hive isolation
> ------------------------------------------------------------
>
> Key: SPARK-26839
> URL: https://issues.apache.org/jira/browse/SPARK-26839
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: Imran Rashid
> Assignee: Sean Owen
> Priority: Major
> Fix For: 3.0.0
>
>
> Java 9+ changed how ClassLoaders work. The two most salient points:
> The boot classloader no longer 'sees' the platform classes. A new 'platform
> classloader' does and should be the parent of new ClassLoaders
> The system classloader is no longer a URLClassLoader, so we can't get the
> URLs of JARs in its classpath
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