java.lang.StackOverflowError in pio train phase
<p><code>pio train</code> (after a successful <code>pio build</code>)  gives me an error like that:</p>

<pre><code>[ERROR] [Executor] Exception in task 0.0 in stage 39.0 (TID 34)
[WARN] [TaskSetManager] Lost task 0.0 in stage 39.0 (TID 34, localhost): java.lang.StackOverflowError
at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2321)
at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2614)
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2624)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1321)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:373)
at scala.collection.immutable.$colon$colon.readObject(List.scala:362)
at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1058)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1909)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1808)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1353)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2018)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1942)
</code></pre>

<p>From here, the ObjectInputStreams etc. repeat more or less till the stack is full.</p>

<p>Does anyone have a hint what this might be or how to debug this?</p>

<p><strong>NB</strong>: I'm running prediction.io inside a docker container which might (?) cause the problem, but again: I do not really know how to go on from there.</p>

<p>Any help is truly appreciated.</p>

<p>PS: I increased the stacksize using  <code>SPARK_DAEMON_JAVA_OPTS="-Xss=9m"</code>with no effect, but I guess an infinite recursion is the culprit anyway.</p>