1 Commits

Include renames

Author	SHA1	Message	Date
romanettandClaude Opus 5.5	0716603543	Fix concurrent session creation on a shared ClientChannelManager channel (#4739) ... # Description Sessions created concurrently through one `ClientChannelManager` against the same endpoint (`Session.CreateAsync(IClientChannelManager, ...)`) failed with `BadSecureChannelClosed 'The managed transport is closed.'`, and the log showed `Background operation OpenChannel started by ClientChannelManager failed. Channel is Closed.` Creating the same sessions one after another worked. ## Root cause A caller that finds an existing shared entry gets a lease right away, even while the entry's creator is still opening the transport: 1. That session's `OpenAsync` called `lease.Entry.SnapshotClientCertificate()` before any transport was installed and threw *"The managed transport is closed."* 2. The failed session disposed its lease. The refcount dropped to 0 and the entry was torn down. 3. The creator's in-flight `OpenInitialAsync` then found the entry closing and threw *"Channel is Closed."* Every session attached to that entry failed. ## Changes - **`Session.OpenAsync`** waits until the shared entry has an installed transport (new `ChannelEntry.WaitForTransportAsync`) before it reads the certificate. The signal fires when the initial open installs a transport, or when a reconnect that started during the initial open does. It does not wait for `Ready`: `OpenCoreAsync` also runs for session recreate inside a reconnect cycle, and the cycle installs the transport before participants reactivate. - **`ClientChannelManager.GetCoreAsync`**: the creator holds no lease while it opens the entry, so other participants' releases can close the entry under the open. The creator now retries on a fresh entry instead of failing. When the initial open fails on its own, the entry records it (`InitialOpenFaulted`, set under the entry lock at failure time, because the later lifecycle state cannot tell the two cases apart). A faulted open, or one closed by manager disposal, still fails the creator. ## Tests - `SharedChannelConcurrentSessionTests.SessionAttachedWhileChannelOpensWaitsForTransportAsync` (Client.Tests): holds the creator's transport through gated channel bindings until a second session has attached to the opening entry, then checks that both sessions open and share the channel. Fails deterministically without the fix. - `ClientChannelManagerManagedTests.WaitForTransportWaitsForReconnectStartedDuringInitialOpenAsync` and `CreatorDoesNotRetryInitialOpenThatFaultedAsync` (Core.Tests): cover the reconnect-during-open wait and the no-retry-on-fault path. - `SharedChannelConcurrentSessionTests.ConcurrentlyCreatedSessionsShareOneChannelAsync` (Client.Tests): creates 20 sessions concurrently through one manager against the reference server. It checks that they share one channel with refcount 20 and that every session can read. Fails without the fix. - `ClientChannelManagerManagedTests.CreatorRetriesWhenLeaseReleasedDuringInitialOpenAsync` (Core.Tests): holds the initial open with a mock transport, then attaches and releases a second lease during it. It checks that the creator gets a lease on a fresh entry. Fails without the fix with "Channel is Closed." Verification: - **Local runs (net10.0, sequential):** Opc.Ua.Client.Tests 2778 passed; Opc.Ua.Sessions.Tests 851 passed, 379 skipped; Opc.Ua.Core.Tests 6241 passed, 88 skipped. - **net48:** Client.Tests and Core.Tests compile cleanly. - **ServerLoadHarness repro:** `--client shared --sessions 20 --connect-parallel 4/20` now connects every run. The same build without the fix still fails. Note: when the creator's open is cut short this way, the `OpenChannel` background failure is still logged at `fail` level even though the creator now recovers. ## Related Issues - None filed yet. Found while load-testing the shared-channel client with the ServerLoadHarness. ## Checklist - [x] I have signed the [CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf) and read the [CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md) doc. - [x] I have added tests that prove my fix is effective or that my feature works and increased code coverage. - [x] I have added all necessary documentation. - [x] I have verified that my changes do not introduce (new) build or analyzer warnings. - [ ] I ran **all** tests locally using the **UA.slnx** solution against at least .net **framework** and .net **10**, and all passed. - [ ] I fixed **all** failing and flaky tests in the CI pipelines and **all** CodeQL warnings. - [ ] I have addressed **all** PR feedback received. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-12 07:04:41 +02:00