nf/nfc do not seem to be threadsafe and throw NullPointerException

Most appropriate sub-area of Processing 4?

Core/Environment/Rendering

Processing version

3 to current

Operating system

Linux

Steps to reproduce this

"1. Create a method calling nf(float, int, int), nf(int, int), nfc(float, int)

2. Run this method within a thread thread("myFunction").

3. Let it run for a longer time"

This is a little bit harder to reproduce and I only got it first with a complex project.

After a while you will end up with either a Stackoverflow or NullPointerException like this.

java.lang.NullPointerException: Cannot assign field "fastPathContainer" because "this.fastPathData" is null
    at java.base/java.text.DecimalFormat.resetFastPathData(DecimalFormat.java:1157)
    at java.base/java.text.DecimalFormat.checkAndSetFastPathStatus(DecimalFormat.java:1081)
    at java.base/java.text.DecimalFormat.fastFormat(DecimalFormat.java:1659)
    at java.base/java.text.NumberFormat.format(NumberFormat.java:327)
    at processing.core.PApplet.nf(PApplet.java:10108)
    at core3.app.gui.GUIInfo.pre(GUIInfo.java:413)
    at jdk.internal.reflect.GeneratedMethodAccessor24.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:569)
    at processing.core.PApplet$RegisteredMethods.handle(PApplet.java:1436)
    at processing.core.PApplet$RegisteredMethods.handle(PApplet.java:1429)
    at processing.core.PApplet.handleMethods(PApplet.java:1628)
    at processing.core.PApplet.handleDraw(PApplet.java:2473)
    at processing.opengl.PSurfaceJOGL$DrawListener.display(PSurfaceJOGL.java:866)
    at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:692)
    at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:674)
    at jogamp.opengl.GLAutoDrawableBase$2.run(GLAutoDrawableBase.java:443)
    at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1293)
    at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:1147)
    at com.jogamp.newt.opengl.GLWindow.display(GLWindow.java:759)
    at com.jogamp.opengl.util.AWTAnimatorImpl.display(AWTAnimatorImpl.java:81)
    at com.jogamp.opengl.util.AnimatorBase.display(AnimatorBase.java:452)
    at com.jogamp.opengl.util.FPSAnimator$MainTask.run(FPSAnimator.java:178)
    at java.base/java.util.TimerThread.mainLoop(Timer.java:566)
    at java.base/java.util.TimerThread.run(Timer.java:516) 

snippet

Additional context

Doing a little bit research, the NumberFormat in nf/nfc seems not to be thread safe. General consent on this seems to be to use a ThreadLocal. So modifying PApplet like this, seems to fix it.

private static final ThreadLocal<NumberFormat> threadLocalIntNf = ThreadLocal.withInitial(() -> {
  NumberFormat nf = NumberFormat.getInstance();
  nf.setGroupingUsed(false); // no commas
  nf.setMinimumFractionDigits(0);
  nf.setMaximumFractionDigits(0);
  return nf;
});


  static public String nf(float num, int left, int right) {
//    if ((float_nf != null) &&
//        (float_nf_left == left) &&
//        (float_nf_right == right) &&
//        !float_nf_commas) {
//      return float_nf.format(num);
//    }

    float_nf = threadLocalIntNf.get();
    float_nf.setGroupingUsed(false);
    float_nf_commas = false;

    float_nf.setMinimumIntegerDigits(left);
    float_nf.setMinimumFractionDigits(right);
    float_nf.setMaximumFractionDigits(right);

    return float_nf.format(num);
  }

Would you like to work on the issue?

I can provide my fix, but it needs some optimisation/cleanup.

Commencez dans processing.core.PApplet, au niveau de l'appel nf indiqué dans la trace de la pile, puis examinez les chemins de formatage nf et nfc associés ainsi que leur état NumberFormat. Exécutez de manière répétée la reproduction multithread avec nf(float, int, int), nf(int, int) et nfc(float, int) ; le travail est terminé lorsque l'exécution concurrente ne produit plus la NullPointerException ni le StackOverflow signalés.