ConcurrentModificationException in RxJavaPlugins.getPluginImplementationViaProperty

[niqo01]

I am using RxJava 1.1.1 on Android and getting the following error:

Caused by java.util.ConcurrentModificationException
       at java.util.Hashtable$HashIterator.nextEntry(Hashtable.java:727)
       at java.util.Hashtable$EntryIterator.next(Hashtable.java:778)
       at java.util.Hashtable$EntryIterator.next(Hashtable.java:776)
       at rx.plugins.RxJavaPlugins.getPluginImplementationViaProperty(RxJavaPlugins.java:177)
       at rx.plugins.RxJavaPlugins.getSchedulersHook(RxJavaPlugins.java:232)
       at rx.schedulers.Schedulers.(Schedulers.java)
       at rx.schedulers.Schedulers.(Schedulers.java)

My code is

unreadConversationsServer = unreadConversations;
      final Scheduler.Worker worker = Schedulers.io().createWorker();
      worker.schedule(() -> {
        try {
          computeUnreadUnSyncedConversationCount();
        } catch (Exception e) {
          Timber.e(e, "Error while computing Unread Unsynced Conversation Count");
        }
        worker.unsubscribe();
      });

Full detail here: http://crashes.to/s/4ecb8083b7f

[akarnokd]

You seem to have something changing System.getProperties() concurrently with the initialization of the plugin.

[artem-zinnatullin]

Ping @niqo01: were you able to fix the problem?

@akarnokd gave most possible reason of the issue, probably some third-party library modifies system properties concurrently (you can debug access to system properties to find that out).

// We can try to clone() properties before iterating over them (it's a Hashtable (ew) which is synchronized almost everywhere but iterating), but personally, I'd like to not do it if possible.

[akarnokd]

I don't know what kind of map it is thus copying might have the same issue. We could catch the CME and retry the operation with a fresh iterator.

[zsxwing]

clone looks good to me, since it's called only once for each hook. We won't lose any performance after warming up.

I don't know what kind of map it is thus copying might have the same issue. We could catch the CME and retry the operation with a fresh iterator.

According to the javadoc of Properties, I think clone is safe.

Each key and its corresponding value in the property list is a string.
Because Properties inherits from Hashtable, the put and putAll methods can be applied to a Properties object. Their use is strongly discouraged as they allow the caller to insert entries whose keys or values are not Strings. The setProperty method should be used instead. If the store or save method is called on a "compromised" Properties object that contains a non- String key or value, the call will fail. Similarly, the call to the propertyNames or list method will fail if it is called on a "compromised" Properties object that contains a non- String key.

[akarnokd]

@zsxwing Great!

PR welcome.

[akarnokd]

Closing via #3822