We are seeing netty report memory leak erros like the one below after switching to 2.1.
ERROR ResourceLeakDetector: LEAK: ByteBuf.release() was not called before it's garbage-collected. Enable advanced leak reporting to find out where the leak occurred. To enable advanced leak reporting, specify the JVM option '-Dio.netty.leakDetection.level=advanced' or call ResourceLeakDetector.setLevel() See http:
Looking a bit deeper, Spark is not leaking any memory here, but it is confusing for the user to see the error message in the driver logs.
After enabling, '-Dio.netty.leakDetection.level=advanced', netty reveals the SparkSaslServer to be the source of these leaks.
Sample trace :https://gist.github.com/dhruve/b299ebc35aa0a185c244a0468927daf1