Hi Mariano,
I had the same problems with my app. After reading a little bit on the
SQLite Website my understanding was that locking is done with process
(thread) locks. So there are many reader treads possible, but only one
writer thread. For this reason your SQLiteDatabase object needs to be
a singleton. I think otherwise the database file will be opened
several times. In my app I get the singleton with:
mDatabase = dbOpenerHelper.getWritableDatabase();
This is only called once and every call to the Database uses the same
mDatabase object,
Every time I read in the database I do not open a transaction, only a
cursor, like this:
public static PlaylistItem queryCurrentTrackInDB(SQLiteDatabase db,
String playlistID) {
PlaylistItem ret = null;
String whereClause = PlaylistItem.COL_PLAYLIST_ID + "=?";
String[] whereValues = new String[] { playlistID };
String orderClause = PlaylistItem.COL_CURRENT_TRACK + " DESC," +
PlaylistItem.COL_NUMBER;
Cursor cur = db.query(IConstants.PLAYLIST_TABLE, null,
whereClause,
whereValues, null, null, orderClause, "2");
if (cur.moveToFirst()) {
ret = new PlaylistItem(cur);
}
cur.close();
return ret;
}
Every time I write to the database I use a transaction:
public static boolean deletePlaylistByID(SQLiteDatabase db, String
playlistID) {
db.beginTransaction();
int r = 0;
try {
String whereClause = PlaylistItem.COL_PLAYLIST_ID +
"=?";
String[] whereValues = new String[] { playlistID};
r = db.delete(IConstants.PLAYLIST_TABLE, whereClause,
whereValues);
db.setTransactionSuccessful();
} finally {
db.endTransaction();
}
return r > 0;
}
I have a lot of concurrency in my app and after changing it the
described way it works quite well.
Mirko
On 23 Okt., 18:14, Mariano Kamp <[email protected]> wrote:
> Hi,
>
> I have implemented a slow search provider that queries my database. Now
> when at the same time I do another read access my applications stalls (ANR).
>
> It's both read and I don't see why there should be a lock. What are my
> options to get a little more concurrency here?
>
> Cheers,
> Mariano
>
> Here are the two threads that block each other.
>
> One:
> "main" prio=5 tid=3 WAIT
> | group="main" sCount=1 dsCount=0 s=N obj=0x4001db08 self=0xbc48
> | sysTid=2680 nice=0 sched=0/0 handle=-1343996920
> at java.lang.Object.wait(Native Method)
> - waiting on <0x271f30> (a java.lang.VMThread)
> at java.lang.Thread.parkFor(Thread.java:1499)
> at java.lang.LangAccessImpl.parkFor(LangAccessImpl.java:48)
> at sun.misc.Unsafe.park(Unsafe.java:319)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:117)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:680)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:710)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1040)
> at
> java.util.concurrent.locks.ReentrantLock$FairSync.lock(ReentrantLock.java:193)
> at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:252)
> at android.database.sqlite.SQLiteDatabase.lock(SQLiteDatabase.java:292)
> at
> android.database.sqlite.SQLiteDatabase.addSQLiteClosable(SQLiteDatabase.java:221)
> at android.database.sqlite.SQLiteProgram.<i
> nit>(SQLiteProgram.java:57)
> at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:49)
> at
> android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:49)
> at
> android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1118)
> at
> android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1092)
> at com.newsrob.DB.findCursorByQueryString(DB.java:419)
> at com.newsrob.EntryManager.getArticleAsCursor(EntryManager.java:1010)
> at
> com.newsrob.activities.ShowArticleActivity.onCreate(ShowArticleActivity.java:81)
> at
> android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
> at
> android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2364)
> at
> android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417)
> at android.app.ActivityThread.access$2100(ActivityThread.java:116)
> at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
> at android.os.Handler.dispatchMessage(Handler.java:99)
> at android.os.Looper.loop(Looper.java:123)
> at android.app.ActivityThread.main(ActivityThread.java:4203)
> at java.lang.reflect.Method.invokeNative(Native Method)
> at java.lang.reflect.Method.invoke(Method.java:521)
> at
> com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
> at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
> at dalvik.system.NativeStart.main(Native Method)
>
> Two:
> "Binder Thread #4" prio=5 tid=17 NATIVE
> | group="main" sCount=1 dsCount=0 s=N obj=0x432685c8 self=0x231ee8
> | sysTid=2690 nice=10 sched=0/0 handle=2315224
> at android.database.sqlite.SQLiteQuery.native_fill_window(Native Method)
> at android.database.sqlite.SQLiteQuery.fillWindow(SQLiteQuery.java:75)
> at android.database.sqlite.SQLiteCursor.fillWindow(SQLiteCursor.java:288)
> at android.database.sqlite.SQLiteCursor.getCount(SQLiteCursor.java:269)
> at android.database.AbstractCursor.moveToPosition(AbstractCursor.java:171)
> at android.database.AbstractCursor.moveToNext(AbstractCursor.java:256)
> at
> com.newsrob.search.SearchProvider.getSuggestions(SearchProvider.java:80)
> at com.newsrob.search.SearchProvider.query(SearchProvider.java:68)
> at
> android.content.ContentProvider$Transport.bulkQuery(ContentProvider.java:116)
> at
> android.content.ContentProviderNative.onTransact(ContentProviderNative.java:97)
> at android.os.Binder.execTransact(Binder.java:287)
> at dalvik.system.NativeStart.run(Native Method)
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
-~----------~----~----~----~------~----~------~--~---
