Hello René,
I'm glad you got things to work! and thanks for confirming this was
the issue behind #6680 :-)
Sebastien
On Thu, Aug 30, 2012 at 2:32 PM, René Ruppert <rene.rupp...@gmail.com> wrote:
> Hi Sebastien,
>
> I made a small test where one Task would constantly read and another one
> would constantly write.
>
> Task oTask = Task.Factory.StartNew(delegate {
> while(true)
> {
> AppDelegateBase.MasterDatabase.ReadConfigValue(CONFIG_CONSTANTS.CalendarShowAllAppointments,
> "");
> Console.WriteLine("Reading.");
> }
> } );
>
> Task oTask2 = Task.Factory.StartNew(delegate {
> while(true)
> {
> AppDelegateBase.MasterDatabase.WriteConfigValue(CONFIG_CONSTANTS.CalendarShowAllAppointments,
> "1");
> Console.WriteLine("Writing.");
> }
> } );
>
> Than I played with the config. Without any specific config, I get after a
> short while:
>
> 2012-08-30 20:28:07.862 BrainloopBrowser[3400:5203] Reading.
> 2012-08-30 20:28:07.863 BrainloopBrowser[3400:5203] Reading.
> Stacktrace:
>
> at (wrapper managed-to-native)
> Mono.Data.Sqlite.UnsafeNativeMethods.sqlite3_prepare
> (intptr,intptr,int,intptr&,intptr&) <IL 0x0002a, 0xffffffff>
> at Mono.Data.Sqlite.SQLite3.Prepare
> (Mono.Data.Sqlite.SqliteConnection,string,Mono.Data.Sqlite.SqliteStatement,uint,string&)
> [0x00287] in
> /Developer/MonoTouch/Source/mono/mcs/class/Mono.Data.Sqlite/Mono.Data.Sqlite_2.0/SQLite3.cs:355
>
> And that seems to be exactly what I reported in the bug
> https://bugzilla.xamarin.com/show_bug.cgi?id=6680.
>
> Using
>
> SqliteConnection.SetConfig( SQLiteConfig.Serialized );
>
> fixes the issue, while SQLiteConfig.MultiThreaded doesn't - but as you
> explained, I share the connection.
>
> Serialized access is exactly what I want. Even if there are more threads, I
> don't want them to access the DB at the same time.
> However, now I'll have to check for deadlocks, but so far it's all looking
> great.
>
> So as most of the time: your analysis was correct! Thanks a lot!
>
> René
>
> Am 29.08.2012 um 22:34 schrieb Sebastien Pouliot <sebast...@xamarin.com>:
>
> Hello René,
>
> On Wed, Aug 29, 2012 at 2:49 PM, René Ruppert <rene.rupp...@gmail.com>
> wrote:
>
> Thanks for the analysis. So the quick fix would be to set Sqlite to
> multithread mode?
>
>
> Yes, that's the first thing to try. Now sqlite multithread mode [1]
> does not allow you to share the same connection across threads.
>
> <quote>
> Multi-thread. In this mode, SQLite can be safely used by multiple
> threads provided that no single database connection is used
> simultaneously in two or more threads.
> </quote>
>
> If I set it to support multi threading, can I share the connection or is a
> new connection required for every query?
>
>
> Only if you use `serialized` mode.
>
> <quote>
> Serialized. In serialized mode, SQLite can be safely used by multiple
> threads with no restriction.
> </quote>
>
> Note that the document can be misleading (fwiw it's not an iOS-related
> document) since `serialized` is the "generic" default for sqlite, but
> that's not how it was compiled (by Apple) for iOS [2].
>
> Also you need to set this config very early in your process (before
> anything else use sqlite) or it will return an error (and it will be
> ignored). The API to do set this configuration was added in MT 5.1+
> [3].
>
> Please let us know if this fix your issue (and also if you stop seeing
> bug #6680 [4] which could be related to this).
>
> Regards,
> Sebastien
>
> [1] http://www.sqlite.org/threadsafe.html
> [2] http://stackoverflow.com/q/11058098/220643
> [3] http://stackoverflow.com/a/8327682/220643
> [4] https://bugzilla.xamarin.com/show_bug.cgi?id=6680
>
> René
>
> Am 29.08.2012 um 14:59 schrieb Sebastien Pouliot <sebast...@xamarin.com>:
>
> On Wed, Aug 29, 2012 at 4:18 AM, René Ruppert <rene.rupp...@gmail.com>
> wrote:
>
> Hi,
>
> after upgrading from 5.2.13 to 5.3.6, this crash is the first thing I see in
> the 5.1 Simulator on Mountain Lion and this time I can reproduce it.
> I have pasted the full log to a Gist: https://gist.github.com/3508383
>
>
> Inside your gist note that both thread #0 and thread #11 (crasher) are
> running SQLite code at the same time. That's a bad sign if they are
> working on the same instance / data.
>
> I'm using Sqlite3 from another thread, not the UI main thread. I have not
> specified any special options in Sqlite (like multithreading) but I know
> that there is alway exactly one addtional thread and that is querying the
> DB, so this should not be an issue.
>
>
> *one additional* means more than one. That's not ok if there's a
> single connection and that access to it are not controlled (or
> serialized) either by your code or by setting sqlite configuration.
>
> Can somebody see what might be going on?
>
> René
>
> at (wrapper managed-to-native)
> Mono.Data.Sqlite.UnsafeNativeMethods.sqlite3_step (intptr) <IL 0x00025,
> 0xffffffff>
> at Mono.Data.Sqlite.SQLite3.Step (Mono.Data.Sqlite.SqliteStatement)
> [0x0001a] in
> /Developer/MonoTouch/Source/mono/mcs/class/Mono.Data.Sqlite/Mono.Data.Sqlite_2.0/SQLite3.cs:166
> at Mono.Data.Sqlite.SqliteDataReader.NextResult () [0x00129] in
> /Developer/MonoTouch/Source/mono/mcs/class/Mono.Data.Sqlite/Mono.Data.Sqlite_2.0/SQLiteDataReader.cs:913
> at Mono.Data.Sqlite.SqliteDataReader..ctor
> (Mono.Data.Sqlite.SqliteCommand,System.Data.CommandBehavior) [0x00051] in
> /Developer/MonoTouch/Source/mono/mcs/class/Mono.Data.Sqlite/Mono.Data.Sqlite_2.0/SQLiteDataReader.cs:89
> at (wrapper remoting-invoke-with-check)
> Mono.Data.Sqlite.SqliteDataReader..ctor
> (Mono.Data.Sqlite.SqliteCommand,System.Data.CommandBehavior) <IL 0x00021,
> 0xffffffff>
> at Mono.Data.Sqlite.SqliteCommand.ExecuteReader
> (System.Data.CommandBehavior) [0x00006] in
> /Developer/MonoTouch/Source/mono/mcs/class/Mono.Data.Sqlite/Mono.Data.Sqlite_2.0/SQLiteCommand.cs:539
> at Mono.Data.Sqlite.SqliteCommand.ExecuteReader () [0x00000] in
> /Developer/MonoTouch/Source/mono/mcs/class/Mono.Data.Sqlite/Mono.Data.Sqlite_2.0/SQLiteCommand.cs:551
> at (wrapper remoting-invoke-with-check)
> Mono.Data.Sqlite.SqliteCommand.ExecuteReader () <IL 0x00038, 0xffffffff>
> at BrainloopMobile.Items.LocalServer.GetServer (int) [0x00024] in
> /Users/rene/Documents/Develop/Projects/BrainloopMobile/220/BrainloopMobile/BrainloopMobile/Items/LocalServer.cs:202
> at BrainloopMobile.Items.LocalServer.GetAPIManager
> (BrainloopMobile.ServerUniqueDataroomID) [0x00043] in
> /Users/rene/Documents/Develop/Projects/BrainloopMobile/220/BrainloopMobile/BrainloopMobile/Items/LocalServer.cs:468
> at BrainloopMobile.ProgressPreviewItem.ProgressLoop
> (BrainloopMobile.Progress.IProgressContext) [0x00000] in
> /Users/rene/Documents/Develop/Projects/BrainloopMobile/220/BrainloopMobile/BrainloopMobile/Progress/ProgressPreviewItem.cs:160
> at BrainloopMobile.Progress.ModalProgressController.StartProgress ()
> [0x00014] in
> /Users/rene/Documents/Develop/Projects/BrainloopMobile/220/BrainloopMobile/BrainloopMobile/Progress/Base/ModalProgressController.cs:329
> at System.Threading.Thread.StartInternal () [0x0001d] in
> /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading/Thread.cs:697
> at (wrapper runtime-invoke) object.runtime_invoke_void__this__
> (object,intptr,intptr,intptr) <IL 0x0004e, 0xffffffff>
>
> Native stacktrace:
>
> 0 BrainloopBrowser 0x001b877c
> mono_handle_native_sigsegv + 284
> 1 BrainloopBrowser 0x0012f108
> mono_sigsegv_signal_handler + 248
> 2 libsystem_c.dylib 0x9924286b _sigtramp + 43
> 3 ??? 0xffffffff 0x0 + 4294967295
> 4 libsqlite3.dylib 0x03c58b5d sqlite3_step + 2989
>
>
> ^ that's SQLite (#4, native iOS library) calling an invalid pointer
> (#3), triggering the sigtramp (#2, OS), catched/handled by the mono
> runtime (#1, #0).
>
> \/ that's the managed frames (that you have above in the managed stack
> trace)
>
> 5 ??? 0x138a97d7 0x0 + 327849943
> 6 ??? 0x138a94c0 0x0 + 327849152
> 7 ??? 0x138a62ab 0x0 + 327836331
> 8 ??? 0x138a5caa 0x0 + 327834794
> 9 ??? 0x138a5b20 0x0 + 327834400
> 10 ??? 0x138a4f04 0x0 + 327831300
> 11 ??? 0x138ad4f8 0x0 + 327865592
> 12 ??? 0x138ad494 0x0 + 327865492
> 13 ??? 0x13eb95d4 0x0 + 334206420
> 14 ??? 0x13bc3234 0x0 + 331100724
> 15 ??? 0x13bc1954 0x0 + 331094356
> 16 ??? 0x13ff0264 0x0 + 335479396
> 17 ??? 0x13f60d26 0x0 + 334892326
> 18 ??? 0x0afb5be4 0x0 + 184245220
> 19 BrainloopBrowser 0x001334c2
> mono_jit_runtime_invoke + 722
> 20 BrainloopBrowser 0x00296b9e mono_runtime_invoke
> + 126
> 21 BrainloopBrowser 0x00296d0c
> mono_runtime_delegate_invoke + 140
> 22 BrainloopBrowser 0x002f6e52 start_wrapper + 482
> 23 BrainloopBrowser 0x00328d6a
> thread_start_routine + 154
> 24 BrainloopBrowser 0x002d38f0 gc_start_thread +
> 80
> 25 libsystem_c.dylib 0x99256557 _pthread_start +
> 344
> 26 libsystem_c.dylib 0x99240cee thread_start + 34
>
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