Summer.removeInput() throws ArrayOutOfBoundsException

[dmitrc]

We have a single-threaded Processing sketch, where we are dealing with a lot of simultaneous playbacks, number of which is capped to an integer variable. After the queue is overfilled, ugens are being unpatched and sound removed from the queue.

However, sometimes (still mysterious), when trying to run pan.unpatch(out);, ArrayOutOfBoundsException is thrown by AudioOutput's Summer object. It tries to access one position beyond the end of an array (that we assume could've changed WHILE the loop was running).

We looked through our code and couldn't pinpoint the source of the problem (ArrayList that's throwing exception belongs to AudioOutput.Summer) - we don't even use ArrayLists. Thus, I am not really sure whether it's a bug or just us overloading Minim, we thought you'd like to know this anyway.

As a suggestion: maybe make Summer's m_ugens array synchronized or save the array's size explicitly, such that no modifications to it are allowed in such way (during unpatching).

Stack trace:

java.lang.RuntimeException: java.lang.IndexOutOfBoundsException: Index: 11, Size: 11
< ... >
Caused by: java.lang.IndexOutOfBoundsException: Index: 11, Size: 11
    at java.util.ArrayList.rangeCheck(ArrayList.java:635)
    at java.util.ArrayList.get(ArrayList.java:411) <- ArrayList = Summer.m_ugens
    at ddf.minim.ugens.Summer.removeInput(Unknown Source) <- (!!!)
    at ddf.minim.UGen.unpatch(Unknown Source)
    at ddf.minim.UGen.unpatch(Unknown Source)
    at main$Sonify$Chain.dispose(main.java:662)
    at main$Sonify.updateSamples(main.java:779)
    at main$Sonify.play(main.java:794)
    at main.draw(main.java:217)

Our code is available here:
http://github.com/dmitryfd/Zond

The problematic part is in Sonify.pde:44 (we put try/catch around it).

Thanks a lot!

[ddf]

Thanks for the excellent report, will try to look into it soon.

[ddf]

Hi, I added synchronization on the ugens list inside Summer and I think this will fix the error you are seeing. Would you be so kind as to grab the lastest minim.jar from here and replace the version you are running against in your Processing setup:

https://github.com/ddf/Minim/tree/master/library

[dmitrc]

Thanks a lot! I will give a try :)

That error was kind of mysterious and not quite trivial to reproduce.
Should it ever pop up again, however, I will let you know here.

[ddf]

Have you seen this crop up again?