NPE when starting Isabelle

[andriusvelykis]

Occurs sporadically:

Exception in thread "session_actor" java.lang.NullPointerException
    at isabelle.Isabelle_Process.input_bytes(isabelle_process.scala:394)
    at isabelle.Isabelle_Process.input(isabelle_process.scala:399)
    at isabelle.Protocol$class.discontinue_execution(protocol.scala:203)
    at isabelle.Session$$anonfun$3$$anonfun$apply$mcV$sp$3$$anon$1.discontinue_execution(session.scala:393)
    at isabelle.Session$$anonfun$3$$anonfun$apply$mcV$sp$3.apply(session.scala:412)
    at isabelle.Session$$anonfun$3$$anonfun$apply$mcV$sp$3.apply(session.scala:387)
    at scala.actors.Actor$class.receiveWithin(Actor.scala:630)
    at scala.actors.ActorProxy.receiveWithin(ActorProxy.scala:20)
    at scala.actors.Actor$.receiveWithin(Actor.scala:208)
    at isabelle.Session$$anonfun$3.apply$mcV$sp(session.scala:387)
    at isabelle.Simple_Thread$$anonfun$1.apply$mcV$sp(simple_thread.scala:46)
    at isabelle.Simple_Thread$$anon$2.run(simple_thread.scala:24)

[makarius]

I think I've seen this before, but can't say on the spot where it is coming from.

Scala-2.9.x had various "can't happen NPEs" due to low-level problems with multithreaded memory access (bad initialization?), especially on Mac OS X, but that should be OK with scala-2.10.0 from Isabelle2013.

[andriusvelykis]

I have not encountered this since upgrading to Scala 2.10 and Isabelle2013 either. The bug report was filed before the upgrade - I'll assume this has been fixed then.

Closing as likely to have been fixed by upgrade to Scala 2.10 and Isabelle/Scala 2013.