efcore: ObjectDisposedException on retrieval of a pooled DbContext

EF Core version: 6.0.0-rc1 Database provider: any Target framework: .NET 6.0 Operating system: any IDE: any

https://github.com/dotnet/efcore/blob/release/6.0/src/EFCore/DbContext.cs#L902 - looks like _disposed field should be set to false here instead (and in the *Async version of the same method). The existing code causes any DbContext that was returned back to the pool to throw ObjectDisposedException on attempt to rent it again.

About this issue

Original URL
State: closed
Created 3 years ago
Comments: 16 (9 by maintainers)

Commits related to this issue

fix: https://github.com/dotnet/efcore/issues/26202 — committed to servicetitan/Stl.Fusion by alexyakunin 3 years ago
fix: a better workaround for https://github.com/dotnet/efcore/issues/26202 — committed to servicetitan/Stl.Fusion by alexyakunin 3 years ago
Fix context pooling concurrency issue Fixes #26202 — committed to dotnet/efcore by roji 3 years ago
Fix context pooling concurrency issue Fixes #26202 — committed to dotnet/efcore by roji 3 years ago
Fix context pooling concurrency issue Fixes #26202 — committed to dotnet/efcore by roji 3 years ago
Fix context pooling concurrency issue Fixes #26202 — committed to dotnet/efcore by roji 3 years ago
Fix context pooling concurrency issue Fixes #26202 — committed to dotnet/efcore by roji 3 years ago
Fix context pooling concurrency issue Fixes #26202 (cherry picked from commit 8e09d658b9748f9d1bfdde8bce1c516042dc3166) — committed to dotnet/efcore by roji 3 years ago
Fix context pooling concurrency issue (#26226) Fixes #26202 — committed to dotnet/efcore by roji 3 years ago
Fix context pooling concurrency issue Fixes #26202 (cherry picked from commit 8e09d658b9748f9d1bfdde8bce1c516042dc3166) — committed to dotnet/efcore by roji 3 years ago

Most upvoted comments

@roji Race condition:

Context is disposed:

        public virtual void Dispose()
        {
            var leaseActive = _lease.IsActive;
            var contextDisposed = leaseActive && _lease.ContextDisposed();

            if (DisposeSync(leaseActive, contextDisposed))
            {
                _serviceScope?.Dispose();
            }
        }

Calls _lease.ContextDisposed();

        public bool ContextDisposed()
        {
            if (_standalone)
            {
                Release();

                return true;
            }

            return false;
        }

Context is now back in the pool. Back to Dispose method, DisposeSync is called:

        private bool DisposeSync(bool leaseActive, bool contextDisposed)
        {
            if (leaseActive)
            {
                if (contextDisposed)
                {
                    _disposed = true;
                    _lease = DbContextLease.InactiveLease;
                }
            }
...

Context is marked as disposed and lease is deactivated. But by this time the context may already have been pulled from the pool again, so we deactivate a context that is in use.

ajcvickers on Sep 30, 2021

@roji Can you prepare a PR cherry-picking this to 5.0.x?

ajcvickers on Oct 4, 2021

FYI I don’t think this bug exists in 3.1 - it doesn’t seem like the DbContext is mutated in any way after being returned to the pool (code).

roji on Oct 3, 2021

@roji , @ajcvickers , huge thanks - I also wanted to post a working example, but just got back to this & was pleasantly surprised!

alexyakunin on Oct 1, 2021