因此，我们在Parse SDK for Android中遇到了这个非常奇怪，看似随机的崩溃。通常我们会将此归因于Parse平台中的一个错误，但它对所有用户来说都是一致的，并且研究问题并没有带来任何已知原因。事实上，只有一个与这个问题有轻微关系的问题，可以在这里找到; link。
基本细分是我们在Crashlytics日志中检测到以下崩溃：
Fatal Exception: java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:300)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:787)
at java.util.HashMap$KeyIterator.next(HashMap.java:814)
at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:960)
at com.parse.ParseTraverser.visit(ParseTraverser.java:100)
at com.parse.ParseTraverser.visit(ParseTraverser.java:94)
at com.parse.ParseTraverser.visit(ParseTraverser.java:101)
at com.parse.ParseTraverser.visit(ParseTraverser.java:94)
at com.parse.ParseTraverser.visit(ParseTraverser.java:101)
at com.parse.ParseTraverser.traverse(ParseTraverser.java:137)
at com.parse.OfflineStore.saveLocallyAsync(OfflineStore.java:776)
at com.parse.OfflineStore.access$200(OfflineStore.java:36)
at com.parse.OfflineStore$38.then(OfflineStore.java:1251)
at com.parse.OfflineStore$38.then(OfflineStore.java:1227)
at bolts.Task$15.run(Task.java:917)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeAfterTask(Task.java:908)
at bolts.Task.continueWithTask(Task.java:715)
at bolts.Task.continueWithTask(Task.java:726)
at bolts.Task$13.then(Task.java:818)
at bolts.Task$13.then(Task.java:806)
at bolts.Task$15.run(Task.java:917)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeAfterTask(Task.java:908)
at bolts.Task.access$100(Task.java:32)
at bolts.Task$11.then(Task.java:708)
at bolts.Task$11.then(Task.java:705)
at bolts.Task.runContinuations(Task.java:956)
at bolts.Task.trySetResult(Task.java:994)
at bolts.TaskCompletionSource.trySetResult(TaskCompletionSource.java:39)
at bolts.TaskCompletionSource.setResult(TaskCompletionSource.java:62)
at bolts.Task$15$1.then(Task.java:934)
at bolts.Task$15$1.then(Task.java:921)
at bolts.Task$14.run(Task.java:872)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeImmediately(Task.java:863)
at bolts.Task.continueWith(Task.java:661)
at bolts.Task.continueWith(Task.java:672)
at bolts.Task$15.run(Task.java:921)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeAfterTask(Task.java:908)
at bolts.Task.access$100(Task.java:32)
at bolts.Task$11.then(Task.java:708)
at bolts.Task$11.then(Task.java:705)
at bolts.Task.runContinuations(Task.java:956)
at bolts.Task.trySetResult(Task.java:994)
at bolts.TaskCompletionSource.trySetResult(TaskCompletionSource.java:39)
at bolts.TaskCompletionSource.setResult(TaskCompletionSource.java:62)
at bolts.Task$15$1.then(Task.java:934)
at bolts.Task$15$1.then(Task.java:921)
at bolts.Task$14.run(Task.java:872)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeImmediately(Task.java:863)
at bolts.Task.continueWith(Task.java:661)
at bolts.Task.continueWith(Task.java:672)
at bolts.Task$15.run(Task.java:921)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeAfterTask(Task.java:908)
at bolts.Task.access$100(Task.java:32)
at bolts.Task$11.then(Task.java:708)
at bolts.Task$11.then(Task.java:705)
at bolts.Task.runContinuations(Task.java:956)
at bolts.Task.trySetResult(Task.java:994)
at bolts.TaskCompletionSource.trySetResult(TaskCompletionSource.java:39)
at bolts.TaskCompletionSource.setResult(TaskCompletionSource.java:62)
at bolts.Task$15$1.then(Task.java:934)
at bolts.Task$15$1.then(Task.java:921)
at bolts.Task$14.run(Task.java:872)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeImmediately(Task.java:863)
at bolts.Task.continueWith(Task.java:661)
at bolts.Task.continueWith(Task.java:672)
at bolts.Task$15.run(Task.java:921)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeAfterTask(Task.java:908)
at bolts.Task.access$100(Task.java:32)
at bolts.Task$11.then(Task.java:708)
at bolts.Task$11.then(Task.java:705)
at bolts.Task.runContinuations(Task.java:956)
at bolts.Task.trySetResult(Task.java:994)
at bolts.TaskCompletionSource.trySetResult(TaskCompletionSource.java:39)
at bolts.TaskCompletionSource.setResult(TaskCompletionSource.java:62)
at bolts.Task$15$1.then(Task.java:934)
at bolts.Task$15$1.then(Task.java:921)
at bolts.Task$14.run(Task.java:872)
at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
at bolts.Task.completeImmediately(Task.java:863)
at bolts.Task.continueWith(Task.java:661)
at bolts.Task.continueWith(Task.java:672)
at bolts.Task$15.run(Task.java:921)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
现在你可以看到这个堆栈跟踪没有向我们展示我们的代码中发生问题的位置，并且我们无法一致地重现它。它似乎随机弹出，与我之前链接的问题相反。
有没有人对此问题有任何经验？如果是这样，是什么导致了这个？我已经检查了我们的代码是否通过ParseObject列表循环并删除了条目，但是我找不到任何这种情况的实例。