潜在的多线程调用可能引发的崩溃

https://github.com/lingochamp/FileDownloader/blob/6237a8cac174bcc916e4342b14ab1ab72a5768d4/library/src/main/java/com/liulishuo/filedownloader/message/MessageSnapshotThreadPool.java#L101

该行代码，可能由于多线程调用而导致崩溃吧？

Start with library/src/main/java/com/liulishuo/filedownloader/message/MessageSnapshotThreadPool.java at line 101 and inspect how concurrent calls reach that code. Determine whether the reported crash can be reproduced and identify the relevant concurrency behavior. Done when the concern is confirmed or ruled out with appropriate regression coverage.

Written by the indexing model from the issue text.