PrBabysitter platform-build trigger aborts with OutOfMemoryException during message deserialization — event-triggered passes stop until recycle

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Valutazione

Difficoltà
4/5
Tempo stimato
3-5 giorni
Idoneità per principianti
35/100
Tipo di issue
Bug
Chiarezza
Abbastanza chiara
Stato di attività
Attiva
Stack tecnologico
csharp, json
Ambito
backend, observability

Direzione di ricerca

Start with MeshWeaver.Messaging.Hub/Serialization/ObjectPolymorphicConverter.cs, especially TryReadRegisteredTypeFromReader and ReadObject, then inspect the trigger wiring in Hosting/Deployment/Source/PrBabysitter.cs. Compare the pod memory limit with delivery sizes in Hosting/PlatformBuilds/_Inbox and Hosting/Babysitter/_Inbox to distinguish memory pressure from an oversized payload. Done means identifying the cause and addressing the deserialization failure without disabling the trigger.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

bug sev:M

What is failing

The PR babysitter's platform-build trigger on the build instance (the Hosting/PlatformBuilds hub, namespace memex) aborted while deserializing an inbound message: MeshWeaver.Messaging's ObjectPolymorphicConverter hit a System.OutOfMemoryException mid-read (the failing allocation is System.Text.Json's string transcode/unescape). The handler caught it and disabled the trigger for that hub — so event- and build-triggered passes no longer fire, while the 30-minute fallback schedule continues to run full passes.

Probable cause — medium-low confidence; the evidence does not single one out:

  • An OOM raised inside JsonReaderHelper.TranscodeHelper means one ordinary string allocation failed — that almost always means the pod was already at its memory ceiling (container limit / LOH fragmentation) when the payload was read, rather than that this one message was pathologically large.
  • The competing explanation is an oversized message payload being deserialized on this hub (a forwarded GitHub event or platform-build delivery). Nothing in the incident distinguishes the two; the pod's memory metrics and the size of the undecoded delivery would.

Impact

Single occurrence on a single pod. The babysitter is degraded, not down: red pull requests are still classified by the scheduled 30-minute passes, heals are still proposed, and the page stays current at schedule cadence. What is lost until the hub/pod is recycled is event responsiveness — reds are no longer caught within a minute of the event, which the Hosting/PrBabysitter doc already names as the price of a schedule-only host. No portal outage and no data loss observed.

Where to look

  • MeshWeaver.Messaging.Hub/Serialization/ObjectPolymorphicConverter.cs — TryReadRegisteredTypeFromReader (line 248 in the burst's stack) and ReadObject (line 118 in a 2026-09-22 burst on the same site): how polymorphic payloads are read and what size guard, if any, exists.
  • The trigger wiring on the Hosting/PlatformBuilds hub: Hosting/Deployment/Source/PrBabysitter.cs (the pass and the schedule; documented in Hosting/PrBabysitter § Triggers and cadence).
  • The pod's memory limit and the size of the last deliveries in Hosting/PlatformBuilds/_Inbox and Hosting/Babysitter/_Inbox on the build instance, to separate memory pressure from an oversized payload.

Possibly related — same component, different defect: Systemorph/MeshWeaver#6120 (a PrBabysitter pass aborts row recording on ThreadNames.Prepared throwing MissingMethodException). Not a duplicate; listed because pass-abort defects at this site are accumulating.

Severity judgement: one occurrence, one pod, an operational automation degraded with a working fallback — sev:M. A human may re-rule if the trigger recurs and the build instance's event-driven healing becomes effectively dead.

Evidence
Fingerprint 076f1d7b309ac5bd
Category PrBabysitter
Severity Error
Exception System.OutOfMemoryException
Top frame MeshWeaver.Messaging.Serialization.ObjectPolymorphicConverter.TryReadRegisteredTypeFromReader(Utf8JsonReader& reader, JsonSerializerOptions options, Object& result)
Namespace memex
Pods memex-portal-deployment-6cfcf78898-gkkdv
Occurrences 1
First seen 2026-10-05 16:28:03Z
Last seen 2026-10-05 16:28:03Z
Routing not determined — no configured route matches the category PrBabysitter. This repository is the configured fallback, not a finding about who owns the fault; the category names the LOGGER, which may not be the subject.
Recent log lines 
2026-10-05 16:28:03Z memex-portal-deployment-6cfcf78898-gkkdv fail: PrBabysitter[0]
      [PrBabysitter] the platform-build trigger STOPPED — the schedule still runs
      System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown.
         at System.Text.Json.JsonReaderHelper.TranscodeHelper(ReadOnlySpan`1 utf8Unescaped)
         at System.Text.Json.JsonReaderHelper.GetUnescapedString(ReadOnlySpan`1 utf8Source)
         at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
         at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
         at System.Text.Json.Serialization.JsonConverter`1.OnTryReadAsObject(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, Object& value)
         at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
         at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, T& value, JsonSerializerOptions options, ReadStack& state)
         at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.DeserializeAsObject(Utf8JsonReader& reader, ReadStack& state)
         at System.Text.Json.JsonSerializer.ReadAsObject(Utf8JsonReader& reader, JsonTypeInfo jsonTypeInfo)
         at MeshWeaver.Messaging.Serialization.ObjectPolymorphicConverter.TryReadRegisteredTypeFromReader(Utf8JsonReader& reader, JsonSerializerOptions options, Object& result) in /home/runner/work/MeshWeaver/MeshWeaver/src/MeshWeaver.Messaging.Hub/Serialization/ObjectPolymorphicConverter.cs:line 248
         at MeshWeaver.Messaging.Serialization.ObjectPolymorphicConverter.ReadObject(Utf8JsonReader& reader, JsonSerializerOptions options) in /home/runner/work/MeshWeaver/MeshWeaver/src/MeshWeaver.Messaging.Hub/…[truncated]

Opened automatically from Admin/_LogIncident/076f1d7b309ac5bd. Recurrences are folded into this issue rather than opening new ones.
It also stands for the whole log site 522dc7d73511e52b: other fingerprints of this site fold in here as comments rather than opening tickets of their own.

Lingua principale
C#
Stelle
12
Fork
5
Merge medio
5h 11m
PR unite (30g)
978

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