[MXNET-1171] Refactor and Fix Memory Leak in FeedForward.scala

• Type: Sub-task
• Status: To Do
• Priority: Major
• Resolution: Unresolved
• Component/s: Apache MXNet Scala API
• Sprint: Scala/Java 1 (07/30-08/13), Scala/Java 2 (08/13-08/27), Scala/Java 4 (09/10-09/24), Scala/Java 5 (09/24-10/08), Scala/Java 6 (10/08 - 10/22), Scala/Java 7 (10/22-11/5), Scala/Java 8 (11/5 - 11/19), Scala/Java 9 (11/19-12/3), Scala/Java 10 (12/3-12/17), Scala/Java 13 (01/14 - 01/28)
• Assignee: Unassigned
• Reporter: Naveen Swamy
• Created: 23/Oct/18 00:24
• Updated: 04/Dec/18 20:58

Description

There is an active memory leak in FeedForward.scala's fit method, the public fit methods call initSymbolParams which in turn calls initParams, initParams allocates NDArrays for _argParams and _auxParams which get overwritten inside the private fit method. 

I have added TODO to fix this issue, creating this JIRA to move on to my story. 

Note that since the ND loses references, PhantomRef should pick up and clean when GC runs.

// TODO: https://issues.apache.org/jira/browse/MXNET-1171
// this leaks memory, initSymbolParams->initParams is already called which allocates
// NDArray in argParams, auxParams and here we are overwriting it by calling again.
// PhantomRef should take care of releasing this when GC is called, however we have to
// wait for the GC call to happen