Concurrency with scala.sys.process.ProcessBuilder -

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i'm using spdf's run method render html pdf file.

run uses scala.sys.process.processbuilder , it's ! method:

/** starts process represented builder, blocks until exits, ,     * returns exit code.  standard output , error sent console.     */   def ! : int

my controller using future asynchronously execute conversion won't spdf block other interim executions? 

 future { pdf.run(sourceurl, outputstream) } map { exitcode =>      outputsteam.tobytearray  }

update

thanks answer paul did little test , yeah looks way :)

if update spdf's run so: 

  def run[a, b](sourcedocument: a, destinationdocument: b)(implicit sourcedocumentlike: sourcedocumentlike[a], destinationdocumentlike: destinationdocumentlike[b]): int = {       println("start/ " + system.currenttimemillis)       < ... code removed ... >       val result = (sink compose source)(process).!       println("finish/ " + system.currenttimemillis)       result   }

and execute 3 consecutive requests stdout prints

start 1461288779013 start 1461288779014 start 1461288779014 finish 1461288781018 finish 1461288781020 finish 1461288781020

which looks asynchronous execution.

this pdf#run:

  def run[a, b](sourcedocument: a, destinationdocument: b)(implicit sourcedocumentlike: sourcedocumentlike[a], destinationdocumentlike: destinationdocumentlike[b]): int = {     val commandline = tocommandline(sourcedocument, destinationdocument)     val process = process(commandline)     def source = sourcedocumentlike.sourcefrom(sourcedocument) _     def sink = destinationdocumentlike.sinkto(destinationdocument) _      (sink compose source)(process).!   }

there's no synchronization prevents parallel execution. assuming executioncontext has enough available threads,

future { pdf.run(sourceurl, outputstream) } map { exitcode =>     outputsteam.tobytearray }  future { pdf.run(sourceurl, outputstream) } map { exitcode =>     outputsteam.tobytearray }

will execute in parallel.

if instead, run method had been, say, surrounded synchronized block, 1 invocation execute per pdf instance. there's no reason prevent concurrency here, author didn't.


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