[jira] [Created] (TIKA-2677) ConcurrentModificationException in org.apache.tika.mime.MediaTypeRegistry.getAliases

["Yuriy Koval (JIRA)" <ji...@apache.org>]

Yuriy Koval created TIKA-2677:
---------------------------------

             Summary: ConcurrentModificationException in org.apache.tika.mime.MediaTypeRegistry.getAliases
                 Key: TIKA-2677
                 URL: https://issues.apache.org/jira/browse/TIKA-2677
             Project: Tika
          Issue Type: Bug
    Affects Versions: 1.18
            Reporter: Yuriy Koval


When using Tika parser on multiple threads and calling MediaTypeRegistry.getAliases, we get ConcurrentModificationException:
{noformat}
java.util.ConcurrentModificationException
 at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
 at java.util.HashMap$EntryIterator.next(HashMap.java:1463)
 at java.util.HashMap$EntryIterator.next(HashMap.java:1461)
 at org.apache.tika.mime.MediaTypeRegistry.getAliases(MediaTypeRegistry.java:78){noformat}
It will go away, if we use ConcurrentMap here:

[https://github.com/apache/tika/blob/master/tika-core/src/main/java/org/apache/tika/mime/MediaTypeRegistry.java#L49]

 

Here is code snippet to recreate the problem:
{code:java}
static boolean stop = false;
public static void main(String[] args) throws MimeTypeException {
 MimeTypes mimeTypes = MimeTypes.getDefaultMimeTypes();
 Executors.newSingleThreadExecutor().execute(() -> {
 try {
 for (int i=0; i < 1000 && !stop; i++) {
 System.out.println(mimeTypes.forName("abc" + i + "/abc"));
 }
 } catch (MimeTypeException e) {
 e.printStackTrace();
 }
 });
 for (int i=0; i < 1000 && !stop; i++) {
 try {
 System.out.println(mimeTypes.getMediaTypeRegistry().getAliases(MediaType.APPLICATION_ZIP));
 } catch (ConcurrentModificationException ex) {
 stop = true;
 ex.printStackTrace();
 }
 }
}{code}
 



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