Android threading and database locking

Question

We are using AsyncTasks to access database tables and cursors.

Unfortunately we are seeing occasional exceptions regarding the database being locked.

E/SQLiteOpenHelper(15963): Couldn't open iviewnews.db for writing (will try read-only): E/SQLiteOpenHelper(15963): android.database.sqlite.SQLiteException: database is locked E/SQLiteOpenHelper(15963):  at     android.database.sqlite.SQLiteDatabase.native_setLocale(Native Method) E/SQLiteOpenHelper(15963):  at     android.database.sqlite.SQLiteDatabase.setLocale(SQLiteDatabase.java:1637) E/SQLiteOpenHelper(15963):  at     android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1587) E/SQLiteOpenHelper(15963):  at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:638) E/SQLiteOpenHelper(15963):  at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:659) E/SQLiteOpenHelper(15963):  at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:652) E/SQLiteOpenHelper(15963):  at android.app.ApplicationContext.openOrCreateDatabase(ApplicationContext.java:482) E/SQLiteOpenHelper(15963):  at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:193) E/SQLiteOpenHelper(15963):  at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:98) E/SQLiteOpenHelper(15963):  at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:158) E/SQLiteOpenHelper(15963):  at com.iview.android.widget.IViewNewsTopStoryWidget.initData(IViewNewsTopStoryWidget.java:73) E/SQLiteOpenHelper(15963):  at com.iview.android.widget.IViewNewsTopStoryWidget.updateNewsWidgets(IViewNewsTopStoryWidget.java:121) E/SQLiteOpenHelper(15963):  at com.iview.android.async.GetNewsTask.doInBackground(GetNewsTask.java:338) E/SQLiteOpenHelper(15963):  at com.iview.android.async.GetNewsTask.doInBackground(GetNewsTask.java:1) E/SQLiteOpenHelper(15963):  at android.os.AsyncTask$2.call(AsyncTask.java:185) E/SQLiteOpenHelper(15963):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:256) E/SQLiteOpenHelper(15963):  at java.util.concurrent.FutureTask.run(FutureTask.java:122) E/SQLiteOpenHelper(15963):  at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:648) E/SQLiteOpenHelper(15963):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:673) E/SQLiteOpenHelper(15963):  at java.lang.Thread.run(Thread.java:1060) 

Does anybody have a general example for code which writes to a database from a different thread than the one reading and how can we ensure thread safety.

One suggestion I've had is to use a ContentProvider, as this would handle the access of the database from multiple threads. I am going to look at this, but is this the recommended method of handling such a problem? It seems rather heavyweight considering we're talking about in front or behind.

Answer 1

We used a ContentProvider in the end. This appeared to clear up the problems.