NoSuchElementException in LiftSession:1012

[Andreas Joseph Krogh]

Hi all.

 

From time to time I get this in my logs:

 

2015-03-13 16:00:46,731 ERROR [liftExecutor-1-thread-808] - [] []  ActorLogger                    - Actor threw an exception
java.util.NoSuchElementException: None.get
at scala.None.get(Option.scala:347)
at scala.None.get(Option.scala:345)
at net.liftweb.http.LiftSession.run1(LiftSession.scala:1012)
at net.liftweb.http.LiftSession.postPageJavaScript(LiftSession.scala:1024)
at net.liftweb.http.LiftSessionanonfunpostPageJavaScript1.apply(LiftSession.scala:1040)
at net.liftweb.http.LiftSessionanonfunpostPageJavaScript1.apply(LiftSession.scala:1039)
at scala.collection.immutable.List.flatMap(List.scala:327)
at net.liftweb.http.LiftSession.postPageJavaScript(LiftSession.scala:1039)

 

The offending code looks like this:

 

org match {
  case None => Nil
  case Some(ppf) => {
    val lb = new ListBuffer[JsCmd]

    def run(count: Int, funcs: List[() => JsCmd]) {
      funcs.reverse.foreach(f => lb += f())
      val next = org.get // safe to do get here because we know the
      // postPageFunc is defined

 

Is there any reason we dont use "ppf" from the extractor Some(ppf)?

 

--

Andreas Joseph Krogh

CTO / Partner - Visena AS

Mobile: +47 909 56 963

and...@visena.com

www.visena.com

[Diego Medina]

I think it is safe to make the change and use
val next = ppf

Thanks

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[Antonio Salazar Cardozo]

I'm not so sure it's safe. run and org are both defs, not vals. They're used to encapsulate

locked access to the post-page functions, which may change while the function is running;

thus this part of the run call:

	// if the function table is updated, make sure to get
	// the additional functions
	if (diff == 0) {} else {
	run(next.functionCount, next.functions.take(diff))
	}

Who is invoking the post-page functions and triggering that exception? Is this happening from

comet or elsewhere?

Thanks,

Antonio

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[Andreas Joseph Krogh]

På lørdag 14. mars 2015 kl. 21:25:06, skrev Antonio Salazar Cardozo <savedf...@gmail.com>:

I'm not so sure it's safe. run and org are both defs, not vals. They're used to encapsulate

locked access to the post-page functions, which may change while the function is running;

thus this part of the run call:

 

	// if the function table is updated, make sure to get
	// the additional functions
	if (diff == 0) {} else {
	run(next.functionCount, next.functions.take(diff))
	}

 

Who is invoking the post-page functions and triggering that exception? Is this happening from

comet or elsewhere?

Thanks,

Antonio

 

The stack-trace suggests that it's from a comet-actor, it contains none of my app's classes.

 

The whole point is that it *does* change because it's a def, hence the NoSuchElementException; First it checks if the reesult of the def is Some, *then* it calls the def again - which might return None this time.

[Antonio Salazar Cardozo]

I definitely agree we need to tweak the implementation to avoid the issue, I'm

just trying to see where in the pipeline the expectations that are implicit in that

function were inaccurate.

I adjusted when post-page functions are looked up for comets when I fixed

issues with comets sent down via AJAX from inside a comet, so I'm wondering

if that triggered this behavior. Are you on 3.0-M3 or later? And if you are, was

this an app that worked without the issue before M3?

Thanks,

Antonio

[Andreas Joseph Krogh]

På søndag 15. mars 2015 kl. 19:22:03, skrev Antonio Salazar Cardozo <savedf...@gmail.com>:

I definitely agree we need to tweak the implementation to avoid the issue, I'm

just trying to see where in the pipeline the expectations that are implicit in that

function were inaccurate.

 

I adjusted when post-page functions are looked up for comets when I fixed

issues with comets sent down via AJAX from inside a comet, so I'm wondering

if that triggered this behavior. Are you on 3.0-M3 or later? And if you are, was

this an app that worked without the issue before M3?

Thanks,

Antonio

 

This happens using 2.6

[Antonio Salazar Cardozo]

Interesting… And strange. Can you post the stack trace through the Lift CometActor

lines? I think I know where this is being triggered, but not 100% sure.

Thanks,

Antonio

[Andreas Joseph Krogh]

På søndag 15. mars 2015 kl. 22:55:24, skrev Antonio Salazar Cardozo <savedf...@gmail.com>:

Interesting… And strange. Can you post the stack trace through the Lift CometActor

lines? I think I know where this is being triggered, but not 100% sure.

Thanks,

Antonio

 

Sure:

 

2015-03-13 09:14:14,390 ERROR [liftExecutor-1-thread-918] - [] []  ActorLogger                    - Actor threw an exception
java.util.NoSuchElementException: None.get
        at scala.None$.get(Option.scala:347)
        at scala.None$.get(Option.scala:345)
        at net.liftweb.http.LiftSession.run$1(LiftSession.scala:1012)
        at net.liftweb.http.LiftSession.postPageJavaScript(LiftSession.scala:1024)
        at net.liftweb.http.LiftSession$$anonfun$postPageJavaScript$1.apply(LiftSession.scala:1040)
        at net.liftweb.http.LiftSession$$anonfun$postPageJavaScript$1.apply(LiftSession.scala:1039)

        at scala.collection.immutable.List.flatMap(List.scala:327)
        at net.liftweb.http.LiftSession.postPageJavaScript(LiftSession.scala:1039)

        at net.liftweb.http.S$$anonfun$2.apply(S.scala:845)
        at net.liftweb.http.S$$anonfun$2.apply(S.scala:844)
        at net.liftweb.common.Full.map(Box.scala:610)
        at net.liftweb.http.S$class.jsToAppend(S.scala:844)
        at net.liftweb.http.S$.jsToAppend(S.scala:47)
        at net.liftweb.http.LiftServlet$$anonfun$21$$anonfun$apply$14$$anonfun$apply$15.apply(LiftServlet.scala:769)
        at net.liftweb.http.LiftServlet$$anonfun$21$$anonfun$apply$14$$anonfun$apply$15.apply(LiftServlet.scala:769)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$generateSnapshotRestorer$1$$anonfun$apply$8$$anonfun$apply$9$$anonfun$apply$10$$anonfun$apply$11.apply(Vars.scala:546)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$generateSnapshotRestorer$1$$anonfun$apply$8$$anonfun$apply$9$$anonfun$apply$10.apply(Vars.scala:545)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$generateSnapshotRestorer$1$$anonfun$apply$8$$anonfun$apply$9.apply(Vars.scala:544)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$generateSnapshotRestorer$1$$anonfun$apply$8.apply(Vars.scala:543)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$generateSnapshotRestorer$1.apply(Vars.scala:542)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$generateSnapshotRestorer$1.apply(Vars.scala:542)
        at net.liftweb.http.S$PageStateHolder.runInContext(S.scala:228)
        at net.liftweb.http.RenderVersion$$anonfun$15$$anonfun$apply$28$$anonfun$16.apply(LiftSession.scala:459)
        at net.liftweb.util.AnyVarTrait$class.doWith(AnyVar.scala:234)
        at net.liftweb.util.AnyVar.doWith(AnyVar.scala:89)
        at net.liftweb.http.RenderVersion$$anonfun$15$$anonfun$apply$28.apply(LiftSession.scala:458)
        at net.liftweb.http.RenderVersion$$anonfun$15$$anonfun$apply$28.apply(LiftSession.scala:454)
        at scala.Option.map(Option.scala:146)
        at net.liftweb.http.RenderVersion$$anonfun$15.apply(LiftSession.scala:454)
        at net.liftweb.http.RenderVersion$$anonfun$15.apply(LiftSession.scala:453)
        at net.liftweb.common.Full.flatMap(Box.scala:612)
        at net.liftweb.http.RenderVersion$.doWith(LiftSession.scala:453)
        at net.liftweb.http.LiftServlet$$anonfun$21$$anonfun$apply$14.apply(LiftServlet.scala:768)
        at net.liftweb.http.LiftServlet$$anonfun$21$$anonfun$apply$14.apply(LiftServlet.scala:767)
        at net.liftweb.common.Full.map(Box.scala:610)
        at net.liftweb.http.LiftServlet$$anonfun$21.apply(LiftServlet.scala:767)
        at net.liftweb.http.LiftServlet$$anonfun$21.apply(LiftServlet.scala:766)
        at net.liftweb.common.Full.flatMap(Box.scala:612)
        at net.liftweb.http.LiftServlet.net$liftweb$http$LiftServlet$$convertAnswersToCometResponse(LiftServlet.scala:766)
        at net.liftweb.http.LiftServlet$$anonfun$17$$anonfun$apply$12.apply(LiftServlet.scala:710)
        at net.liftweb.http.LiftServlet$$anonfun$17$$anonfun$apply$12.apply(LiftServlet.scala:709)
        at net.liftweb.http.S$class.net$liftweb$http$S$$wrapQuery(S.scala:1470)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_nest2InnerInit$1$$anonfun$apply$38.apply(S.scala:1635)
        at net.liftweb.http.S$class.net$liftweb$http$S$$doAround(S.scala:1399)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_nest2InnerInit$1.apply(S.scala:1633)

        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$class.net$liftweb$http$S$$_nest2InnerInit(S.scala:1632)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_innerInit$1$$anonfun$apply$42$$anonfun$apply$43$$anonfun$apply$44$$anonfun$apply$45.apply(S.scala:1678)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$$anonfun$withReq$2.apply(S.scala:1688)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$class.withReq(S.scala:1687)
        at net.liftweb.http.S$.withReq(S.scala:47)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_innerInit$1$$anonfun$apply$42$$anonfun$apply$43$$anonfun$apply$44.apply(S.scala:1674)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_innerInit$1$$anonfun$apply$42$$anonfun$apply$43.apply(S.scala:1672)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_innerInit$1$$anonfun$apply$42.apply(S.scala:1671)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_innerInit$1.apply(S.scala:1670)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$class.net$liftweb$http$S$$_innerInit(S.scala:1669)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_init$2$$anonfun$apply$50$$anonfun$apply$51$$anonfun$apply$52$$anonfun$apply$53$$anonfun$apply$54.apply(S.scala:1711)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_init$2$$anonfun$apply$50$$anonfun$apply$51$$anonfun$apply$52$$anonfun$apply$53.apply(S.scala:1709)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16$$anonfun$apply$17$$anonfun$apply$18$$anonfun$apply$19.apply(Vars.scala:611)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16$$anonfun$apply$17$$anonfun$apply$18.apply(Vars.scala:610)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16$$anonfun$apply$17.apply(Vars.scala:609)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16.apply(Vars.scala:608)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$class.apply(Vars.scala:607)
        at net.liftweb.http.RequestVarHandler$.apply(Vars.scala:507)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_init$2$$anonfun$apply$50$$anonfun$apply$51$$anonfun$apply$52.apply(S.scala:1708)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16$$anonfun$apply$17$$anonfun$apply$18$$anonfun$apply$19.apply(Vars.scala:611)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16$$anonfun$apply$17$$anonfun$apply$18.apply(Vars.scala:610)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16$$anonfun$apply$17.apply(Vars.scala:609)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$$anonfun$apply$16.apply(Vars.scala:608)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.CoreRequestVarHandler$class.apply(Vars.scala:607)
        at net.liftweb.http.TransientRequestVarHandler$.apply(Vars.scala:520)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_init$2$$anonfun$apply$50$$anonfun$apply$51.apply(S.scala:1707)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_init$2$$anonfun$apply$50.apply(S.scala:1706)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$$anonfun$net$liftweb$http$S$$_init$2.apply(S.scala:1705)
        at net.liftweb.util.ThreadGlobal.doWith(ThreadGlobal.scala:71)
        at net.liftweb.http.S$class.net$liftweb$http$S$$_init(S.scala:1704)
        at net.liftweb.http.S$class.init(S.scala:1284)
        at net.liftweb.http.S$.init(S.scala:47)
        at net.liftweb.http.LiftServlet$$anonfun$17.apply(LiftServlet.scala:709)
        at net.liftweb.http.LiftServlet$$anonfun$17.apply(LiftServlet.scala:706)

        at net.liftweb.http.LiftServlet$ContinuationActor$$anonfun$messageHandler$1.applyOrElse(LiftServlet.scala:692)
        at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:36)
        at net.liftweb.actor.LiftActor$class.execTranslate(LiftActor.scala:504)
        at net.liftweb.http.LiftServlet$ContinuationActor.execTranslate(LiftServlet.scala:667)
        at net.liftweb.actor.SpecializedLiftActor$class.net$liftweb$actor$SpecializedLiftActor$$proc2(LiftActor.scala:307)
        at net.liftweb.actor.SpecializedLiftActor$$anonfun$net$liftweb$actor$SpecializedLiftActor$$processMailbox$1.apply$mcV$sp(LiftActor.scala:229)
        at net.liftweb.actor.SpecializedLiftActor$$anonfun$net$liftweb$actor$SpecializedLiftActor$$processMailbox$1.apply(LiftActor.scala:229)
        at net.liftweb.actor.SpecializedLiftActor$$anonfun$net$liftweb$actor$SpecializedLiftActor$$processMailbox$1.apply(LiftActor.scala:229)
        at net.liftweb.actor.SpecializedLiftActor$class.around(LiftActor.scala:243)
        at net.liftweb.http.LiftServlet$ContinuationActor.around(LiftServlet.scala:667)
        at net.liftweb.actor.SpecializedLiftActor$class.net$liftweb$actor$SpecializedLiftActor$$processMailbox(LiftActor.scala:228)
        at net.liftweb.actor.SpecializedLiftActor$$anonfun$2$$anonfun$apply$mcV$sp$1.apply$mcV$sp(LiftActor.scala:192)
        at bootstrap.liftweb.Boot$$anonfun$setupLiftScheduler$1$$anon$1$$anon$2.run(Boot.scala:168)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

 

[Antonio Salazar Cardozo]

Got it. Yeah, I think it's just a broken assumption and that code needs to stop

assuming it will get a Some just because that was checked ahead of time…

Should be pretty easy; if you file an issue I'll try to get to it sometime this coming

weekend.

Thanks,

Antonio

[Andreas Joseph Krogh]

På mandag 16. mars 2015 kl. 03:54:47, skrev Antonio Salazar Cardozo <savedf...@gmail.com>:

Got it. Yeah, I think it's just a broken assumption and that code needs to stop

assuming it will get a Some just because that was checked ahead of time…

Should be pretty easy; if you file an issue I'll try to get to it sometime this coming

weekend.

Thanks,

Antonio

 

Done: https://github.com/lift/framework/issues/1689

[Antonio Salazar Cardozo]

Thanks!