Session Error when commit transaction

[cdwcgt]

I have no idea should it be reported as issues
it looks like realm doesn't work very well on network drives

when program try to commit transaction by transaction.Commit(), it will crash
it failed at https://github.com/realm/realm-dotnet/blob/main/Realm/Realm/Handles/SharedRealmHandle.cs#L504
This problem happens sporadically

I run osu and it tried to load database what save at network mapped drive
This problem will disappear inexplicably and I can't reproduce with local disk

My SDK version is 6.0.202
OS: Windows 11

this is nativeException

stacktrace

2022-06-19 13:19:14 [error]: Realms.Sync.Exceptions.SessionException: ϵͳ  Դ   㣬 ޷        ķ   
2022-06-19 13:19:14 [error]: at Realms.NativeException.ThrowIfNecessary(Func`2 overrider)
2022-06-19 13:19:14 [error]: at Realms.SharedRealmHandle.CommitTransaction()
2022-06-19 13:19:14 [error]: at Realms.Transaction.Commit()
2022-06-19 13:19:14 [error]: at osu.Game.Database.RealmAccess.cleanupPendingDeletions() in Z:\Github\osu\osu.Game\Database\RealmAccess.cs:line 282
2022-06-19 13:19:14 [error]: at osu.Game.Database.RealmAccess..ctor(Storage storage, String filename, GameThread updateThread, IDatabaseContextFactory efContextFactory) in Z:\Github\osu\osu.Game\Database\RealmAccess.cs:line 173
2022-06-19 13:19:19 [error]: An unhandled error has occurred.
2022-06-19 13:19:19 [error]: Realms.Sync.Exceptions.SessionException: ϵͳ  Դ   㣬 ޷        ķ   
2022-06-19 13:19:19 [error]: at Realms.NativeException.ThrowIfNecessary(Func`2 overrider)
2022-06-19 13:19:19 [error]: at Realms.SharedRealmHandle.Compact()
2022-06-19 13:19:19 [error]: at Realms.Realm.Compact(RealmConfigurationBase config)
2022-06-19 13:19:19 [error]: at osu.Game.Database.RealmAccess.Compact() in Z:\Github\osu\osu.Game\Database\RealmAccess.cs:line 298
2022-06-19 13:19:19 [error]: at osu.Game.Database.RealmAccess.BlockAllOperations() in Z:\Github\osu\osu.Game\Database\RealmAccess.cs:line 833
2022-06-19 13:19:19 [error]: at osu.Game.Database.RealmAccess.CreateBackup(String backupFilename, IDisposable blockAllOperations) in Z:\Github\osu\osu.Game\Database\RealmAccess.cs:line 753
2022-06-19 13:19:19 [error]: at osu.Game.Database.RealmAccess..ctor(Storage storage, String filename, GameThread updateThread, IDatabaseContextFactory efContextFactory) in Z:\Github\osu\osu.Game\Database\RealmAccess.cs:line 192
2022-06-19 13:19:19 [error]: at osu.Game.OsuGameBase.load(ReadableKeyCombinationProvider keyCombinationProvider) in Z:\Github\osu\osu.Game\OsuGameBase.cs:line 233

[nirinchev]

Looks like Realm doesn't work on network drives - I found a similar issue here: realm/realm-studio#237, though that doesn't go into detail about why that is. It likely has to do with limitations of mmap of network files (e.g. outlined here):

Although CreateFileMapping works with remote files, it does not keep them coherent. For example, if two computers both map a file as writable, and both change the same page, each computer only sees its own writes to the page. When the data gets updated on the disk, it is not merged.

[peppy]

I think it would also be beneficial for realm to check this at the point of opening a realm and throwing an exception which mentions this. But that's more work at your end and we'd likely be looking to workaround this locally in the mean time.

As realm basically relies on mmap for operation, is it correct thinking that we should be checking whether to proposed location of our realm storage supports mmap, and choose another path if it doesn't?

[finnschiermer]

It is a bit more tricky. Locations may support mmap but only in a limited sense. What Realm need is that multiple memory mappings of the same location are coherent. This is rarely the case for files on a networked drive.