Annotation ConcurrentModificationException during compilation

[kmader]

I have added a few more annotations to my project using the org.scijava.annotations tool and it now is throwing a strange java.util.ConcurrentModificationException during compilation. Has anyone seen this error before? Running a full clean on the project doesn't seem to alleviate the error.

Error:scala: An annotation processor threw an uncaught exception.
Error:scala: Consult the following stack trace for details.
Error:scala: java.util.ConcurrentModificationException
Error:scala:    at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1207)
Error:scala:    at java.util.TreeMap$EntryIterator.next(TreeMap.java:1243)
Error:scala:    at java.util.TreeMap$EntryIterator.next(TreeMap.java:1238)
Error:scala:    at org.scijava.annotations.AbstractIndexWriter.write(AbstractIndexWriter.java:95)
Error:scala:    at org.scijava.annotations.AnnotationProcessor.process(AnnotationProcessor.java:91)
Error:scala:    at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:794)
Error:scala:    at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:705)
Error:scala:    at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91)
Error:scala:    at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035)
Error:scala:    at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176)
Error:scala:    at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170)
Error:scala:    at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856)
Error:scala:    at com.sun.tools.javac.main.Main.compile(Main.java:523)
Error:scala:    at com.sun.tools.javac.main.Main.compile(Main.java:381)
Error:scala:    at com.sun.tools.javac.main.Main.compile(Main.java:370)
Error:scala:    at com.sun.tools.javac.main.Main.compile(Main.java:361)
Error:scala:    at com.sun.tools.javac.Main.compile(Main.java:56)
Error:scala:    at com.sun.tools.javac.Main.main(Main.java:42)

[ctrueden]

Hmm, that's a new one on me. Are you building with parallel builds (i.e., -T xxx flag)?

The strange thing is that all the AbstractIndexWriter methods touching that map are already synchronized—and have been so since the introduction of that class. So it is a bit mysterious!

[kmader]

I am using the standard build in IntelliJ with build modules in parallel disabled but as far as I can tell, the parallel build flags is not something I can control. I have switched line 63 of AbstractIndexWriter.java to

    private final Map<String, Map<String, Object>> map =
        new ConcurrentSkipListMap<String, Map<String, Object>>();

Instead of TreeMap and have not noticed the problem since, but I will test it more to make sure it does not cause other issues.

[ctrueden]

@kmader Great, if the ConcurrentSkipListMap doesn't seem to cause any problems in either performance or behavior, then please feel welcome to file a PR and I'll merge straight away.

[ctrueden]

Fixed in 084f2ba. Thanks for the patch, @kmader!