[GitHub] [cordova-android] breautek commented on issue #924: Crash Report: ConcurrentModificationException

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breautek commented on issue #924: Crash Report: ConcurrentModificationException
URL: https://github.com/apache/cordova-android/issues/924#issuecomment-612563876
 
 
   I believe this is caused because we access these `LinkedHashMap` objects potentially from different threads and these hash maps are not thread safe.
   
   > Note that this implementation is not synchronized. If multiple threads access a linked hash map concurrently, and at least one of the threads modifies the map structurally, it must be synchronized externally. This is typically accomplished by synchronizing on some object that naturally encapsulates the map. If no such object exists, the map should be "wrapped" using the Collections.synchronizedMap method. This is best done at creation time, to prevent accidental unsynchronized access to the map:
      Map m = Collections.synchronizedMap(new LinkedHashMap(...));
   
   https://docs.oracle.com/javase/8/docs/api/java/util/LinkedHashMap.html
   
   However it will be very hard to be confident unless if we can reproduce this reliability. In the above callstacks, it seems to be occurring on the iteration of plugins on responding to a pause or resume event. Unfortunately this isn't necessary the error, it's just tells us that the hash map has changed while we were iterating.
   
   @HansKrywaa can you tell me a little bit of your app? My wild theory is this is related to maybe the webview being unloaded/killed but that would only make sense if your app goes into the background to load up something memory intensive (such as the camera app). Normally under this situation, the webview is suppose to load back up (but the webview environment would be refreshed). I'm thinking there might be a race condition there...

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