Android SQLite 数据库被锁定

Question

我有一个绑定服务运行多个线程来读取和写入 SQLite 数据库。我创建了我的数据库助手的一个实例，并在我的服务的 onCreate 中获得了与数据库的连接，该连接应该在主线程上执行。由于它是一项绑定服务，因此内存中应该只有一个服务实例。但是我仍然得到 当服务尝试打开数据库或其中一个线程尝试执行语句时偶尔会出现异常。

服务代码：

@Override
    public void onCreate() {
        super.onCreate();

        MyDatabaseHelper helper = new MyDatabaseHelper(this);
        database = helper.getWritableDatabase();
}

例外：

java.lang.RuntimeException: Unable to create service uk.co.example.service.MyService: 
   android.database.sqlite.SQLiteException: unable to open database file
at android.app.ActivityThread.handleCreateService(ActivityThread.java:1959)
at android.app.ActivityThread.access$2500(ActivityThread.java:117)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:989)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3691)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.database.sqlite.SQLiteException: unable to open database file
at android.database.sqlite.SQLiteDatabase.dbopen(Native Method)
at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1960)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:887)
at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:965)
at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:958)
at android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:585)
at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:118)
at uk.co.example.service.MyService.onCreate(MyService.java:69)
at android.app.ActivityThread.handleCreateService(ActivityThread.java:1949)
... 10 more

android.database.sqlite.SQLiteException: error code 5: database is locked
at android.database.sqlite.SQLiteStatement.native_execute(Native Method)
at android.database.sqlite.SQLiteStatement.execute(SQLiteStatement.java:61)
at uk.co.example.a.a.a.a(MyTable.java:147)
at uk.co.example.service.b.a.m.run(MySaveTask.java:84)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
at java.lang.Thread.run(Thread.java:1019)

有什么可能导致这种情况的想法吗？

谢谢

大卫

Answer 1

Sqlite 现在支持一种名为 Writing-Ahead Logging 的新日志模式，适用于 sqlite 的并发访问。你可能想看看http://www.sqlite.org/wal.html。