SQLiteDatabaseLockedException 1.7.5版本崩溃

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老师您好：
我在使用1.7.5版本的时候发生了多次上报的崩溃现象，我是在单任务执行的情况下同时下载两个文件。日志如下 该问题主要集中在4.2.2和4.4.2中，还有我在下载过程中会有个极小概率的crash空指针问题，是否会对此造成影响
Caused by: android.database.sqlite.SQLiteDatabaseLockedException: database is locked (code 5)
2.at android.database.sqlite.SQLiteConnection.nativeExecuteForChangedRowCount(Native Method)
3.at android.database.sqlite.SQLiteConnection.executeForChangedRowCount(SQLiteConnection.java:734)
4.at android.database.sqlite.SQLiteSession.executeForChangedRowCount(SQLiteSession.java:754)
5.at android.database.sqlite.SQLiteStatement.executeUpdateDelete(SQLiteStatement.java:64)
6.at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1674)
7.at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1603)
8.at com.networkbench.agent.impl.instrumentation.NBSSQLiteInstrumentation.execSQL(SourceFile:2)
9.at com.liulishuo.filedownloader.h0.d.q(SourceFile:1)
10.at com.liulishuo.filedownloader.h0.c.z(SourceFile:5)
11.at com.liulishuo.filedownloader.h0.c.v(SourceFile:1)
12.at com.liulishuo.filedownloader.h0.c$a.handleMessage(SourceFile:6)
13.at android.os.Handler.dispatchMessage(Handler.java:95)
14.at android.os.Looper.loop(Looper.java:137)
15.at android.os.HandlerThread.run(HandlerThread.java:61)

Start by reproducing two simultaneous downloads on Android 4.2.2 and 4.4.2, then trace the reported stack from h0.d.q through h0.c and its Handler message handling. Confirm whether the SQLiteDatabaseLockedException can be reproduced and determine whether the separately mentioned null-pointer crash is related; done means both failure conditions are understood and separately addressed.

Written by the indexing model from the issue text.