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StreamConfiguration<T>.GetHashCode recurses through SynchronizationStream<T>, corrupting UserIdentityCache lookups #2163
Description
What is failing
MeshWeaver.Data.Serialization.StreamConfiguration<T>.GetHashCode() and MeshWeaver.Data.Serialization.SynchronizationStream<T>.GetHashCode() call into each other via the default ObjectEqualityComparer<T> — the stack trace shows the cycle ObjectEqualityComparer<T>.GetHashCode → StreamConfiguration<T>.GetHashCode → SynchronizationStream<T>.GetHashCode → ObjectEqualityComparer<T>.GetHashCode → … repeating without a base case. The failure surfaced in MeshWeaver.Blazor.Infrastructure.UserIdentityCache.As<User>, where the cache returned a NodeTypeDefinition under a key it thought identified a User ("…is MeshWeaver.Graph.Configuration.NodeTypeDefinition (MeshWeaver.Graph), not convertible").
Probable cause
High confidence on the mechanism, medium confidence on which of the two GetHashCode overrides is the wrong one. StreamConfiguration<T> almost certainly composes a hash that includes its owning SynchronizationStream<T> (or vice-versa) and delegates through EqualityComparer<T>.Default.GetHashCode(field) — where T closes the loop. The UserIdentityCache message is the downstream symptom: with a broken GetHashCode, distinct stream/configuration instances collide in the cache's dictionary and As<T> finds an entry of the wrong CLR type, which it then reports as "not convertible". Only the log line was captured (no exceptionType), so the recursion was caught by the logging call before it ran the pod out of stack — but the next hit could StackOverflow the process.
Impact
Low volume so far: 1 occurrence, one pod (memex-portal-deployment-7cfbf545d9-gtlhr), namespace memex, seen once at 2026-08-24T17:48:16Z. But the defect is in a generic hash contract used by the data-synchronization layer and the Blazor identity cache — any traffic pattern that puts two StreamConfiguration<T> / SynchronizationStream<T> instances into the same dictionary can either return the wrong-typed value silently or overflow the stack and kill the pod. Treat as latent-severe even though the counter is small.
Where to look
MeshWeaver.Data.Serialization.StreamConfiguration<T>.GetHashCode()— top frame; check what fields it hashes and whether any of them route back to the owningSynchronizationStream<T>.MeshWeaver.Data.Serialization.SynchronizationStream<T>.GetHashCode()— the other half of the cycle; if this hashes itsConfiguration(aStreamConfiguration<T>), that's the loop.- Fix is almost certainly to remove the back-reference from one side of the hash (hash by a stable identity — id/name — not by the paired object), or to override neither and fall back to reference equality.
- Downstream:
MeshWeaver.Blazor.Infrastructure.UserIdentityCache.As<T>— its "not convertible" branch is doing the right thing (it noticed the type mismatch instead of casting blindly); no change needed there, but a defensive log at insert-time that flags a key collision would have shortened this triage.
Evidence
| Fingerprint | 6e643370636ed34a |
| Category | MeshWeaver.Blazor.Infrastructure.UserIdentityCache |
| Severity | Error |
| Top frame | MeshWeaver.Data.Serialization.StreamConfiguration1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()` |
| Namespace | memex |
| Pods | memex-portal-deployment-7cfbf545d9-gtlhr |
| Occurrences | 2 |
| First seen | 2026-08-24 17:48:16Z |
| Last seen | 2026-08-24 17:48:16Z |
Recent log lines
2026-08-24 17:48:16Z memex-portal-deployment-7cfbf545d9-gtlhr fail: MeshWeaver.Blazor.Infrastructure.UserIdentityCache[0]
As<User> for User: value is MeshWeaver.Graph.Configuration.NodeTypeDefinition (MeshWeaver.Graph), not convertible
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode(System.__Canon)
at MeshWeaver.Data.Serialization.StreamConfiguration`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at MeshWeaver.Data.Serialization.SynchronizationStream`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode(System.__Canon)
at MeshWeaver.Data.Serialization.StreamConfiguration`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at MeshWeaver.Data.Serialization.SynchronizationStream`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode(System.__Canon)
at MeshWeaver.Data.Serialization.StreamConfiguration`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at MeshWeaver.Data.Serialization.SynchronizationStream`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, …[truncated]
2026-08-24 17:48:16Z memex-portal-deployment-7cfbf545d9-gtlhr fail: MeshWeaver.Blazor.Infrastructure.UserIdentityCache[0]
As<User> for User: value is MeshWeaver.Graph.Configuration.NodeTypeDefinition (MeshWeaver.Graph), not convertible
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode(System.__Canon)
at MeshWeaver.Data.Serialization.StreamConfiguration`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at MeshWeaver.Data.Serialization.SynchronizationStream`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode(System.__Canon)
at MeshWeaver.Data.Serialization.StreamConfiguration`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at MeshWeaver.Data.Serialization.SynchronizationStream`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode(System.__Canon)
at MeshWeaver.Data.Serialization.StreamConfiguration`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at MeshWeaver.Data.Serialization.SynchronizationStream`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetHashCode()
at System.Collections.Generic.ObjectEqualityComparer`1[[System.__Canon, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, …[truncated]
Opened automatically from Admin/_LogIncident/6e643370636ed34a. Recurrences are folded into this issue rather than opening new ones.
Activity
systemorph commentedon Sep 17, 2026
Reopened — this fault is happening again.
Still occurring: 3 more since the last update (5 total).
memex-portal-deployment-7cfbf545d9-gtlhr,memex-portal-deployment-7cfbf545d9-jk5qc,memex-portal-deployment-58c7bb4b9d-97pjfRecent log lines
rbuergi commentedon Sep 17, 2026
Re-closed — the reopen above was on stale evidence (#4577).
The recurrence bot reopened this at
2026-09-17T07:51:17Zunder the headline "this fault is happening again", but the occurrence its own comment cites is OLDER than the close it reverted:Last seen:2026-08-25 01:14:17Z2026-08-25T18:39:21ZSo the counter moved, not the clock — the fault's newest occurrence predates the close, which is the one thing "still happening" has to mean. Root cause and fix:
LogIncidentFiler.Reopenreopened on the sole condition that the issue was closed, while the comment-debt clock pays a final count for incidents whose fault has stopped (the fix, Systemorph/MeshWeaver.Plugins#2014, is written but NOT yet merged — it makes a reopen requireincident.LastSeen > issue.ClosedAt).This restores the close exactly as it stood; nothing is asserted about the defect itself. If the fault happens again, the next occurrence postdates this close and reopens the issue on evidence that means what it says.
One of 53 issues whose reopen was measured stale (129 bot reopens on 2026-09-17, 125 of them inside the 07:51-07:53Z sweep; 76 postdate their close and were left open). Measured and re-closed 2026-09-17 by Claude Opus 5.