ExecutorClassLoader does not ensure proper cleanup of network connections that it opens. If it fails to load a class, it may leak partially-consumed InputStreams that are connected to the REPL's HTTP class server, causing that server to exhaust its thread pool, which can cause the entire job to hang. See [SPARK-6209](https://issues.apache.org/jira/browse/SPARK-6209) for more details, including a bug reproduction.
This patch fixes this issue by ensuring proper cleanup of these resources. It also adds logging for unexpected error cases.
This PR is an extended version of #4935 and adds a regression test.
Author: Josh Rosen <joshrosen@databricks.com>
Closes#4944 from JoshRosen/executorclassloader-leak-master-branch and squashes the following commits:
e0e3c25 [Josh Rosen] Wrap try block around getReponseCode; re-enable keep-alive by closing error stream
961c284 [Josh Rosen] Roll back changes that were added to get the regression test to fail
7ee2261 [Josh Rosen] Add a failing regression test
e2d70a3 [Josh Rosen] Properly clean up after errors in ExecutorClassLoader
7215aa7455