Error in requestLoop() java.lang.NullPointerException

Sorry, this is going to sound really vague but I get the following stacktrace pretty frequently on a server when (I assume) it accepts PUT requests.

I don’t have much to go on here so thought I’d post an issue for a few pointers to help me debug. The server is pretty simple, started up like below and runs just a few HttpService endpoints.

  private def build(): Task[org.http4s.server.Server] = BlazeBuilder
    .withServiceExecutor(DefaultExecutorService)
    .bindHttp(port, "0.0.0.0")
    .mountService(services(), "/")
    .start

The PUT sends a simple JSON body. Not sure what else I can tell you… oh, I’m on 2.12 / 0.16.3a

The stack trace is below

[blaze-nio-fixed-selector-pool-2] ERROR org.http4s.blaze.pipeline.Stage - error in requestLoop()
java.lang.NullPointerException
	at org.http4s.internal.parboiled2.ParserInput$StringBasedParserInput.length(ParserInput.scala:97)
	at org.http4s.internal.parboiled2.Parser.__advance(Parser.scala:228)
	at org.http4s.internal.parboiled2.Parser.runRule$1(Parser.scala:140)
	at org.http4s.internal.parboiled2.Parser.phase0_initialRun$1(Parser.scala:150)
	at org.http4s.internal.parboiled2.Parser.__run(Parser.scala:203)
	at org.http4s.parser.Rfc2616BasicRules$.token(Rfc2616BasicRules.scala:84)
	at org.http4s.Method$.$anonfun$fromString$1(Method.scala:47)
	at scala.collection.MapLike.getOrElse(MapLike.scala:128)
	at scala.collection.MapLike.getOrElse$(MapLike.scala:126)
	at scala.collection.concurrent.TrieMap.getOrElse(TrieMap.scala:631)
	at org.http4s.Method$.fromString(Method.scala:47)
	at org.http4s.server.blaze.Http1ServerParser.collectMessage(Http1ServerParser.scala:48)
	at org.http4s.server.blaze.Http1ServerStage.runRequest(Http1ServerStage.scala:111)
	at org.http4s.server.blaze.Http1ServerStage.reqLoopCallback(Http1ServerStage.scala:97)
	at org.http4s.server.blaze.Http1ServerStage.$anonfun$requestLoop$1(Http1ServerStage.scala:74)
	at org.http4s.server.blaze.Http1ServerStage.$anonfun$requestLoop$1$adapted(Http1ServerStage.scala:74)
	at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:60)
	at org.http4s.blaze.util.Execution$$anon$1.execute(Executor.scala:27)
	at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:68)
	at scala.concurrent.impl.Promise$DefaultPromise.$anonfun$tryComplete$1(Promise.scala:284)
	at scala.concurrent.impl.Promise$DefaultPromise.$anonfun$tryComplete$1$adapted(Promise.scala:284)
	at scala.concurrent.impl.Promise$DefaultPromise.tryComplete(Promise.scala:284)
	at org.http4s.blaze.channel.nio1.NIO1HeadStage.readReady(NIO1HeadStage.scala:61)
	at org.http4s.blaze.channel.nio1.SelectorLoop.run(SelectorLoop.scala:134)

[aspic]

We have been running with this fix in production for roughly 18 hours and haven’t encountered the NPE yet. 😃

[bryce-anderson]

@aspic, fantastic! Thanks for reporting back the results. As @rossabaker said, if this pops up again please reopen.