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Grain-call cancellation delivery times out against departing silos — cancellation batches not propagated during silo lifecycle events

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
18/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Active
Tech stack
csharp, kubernetes
Domain
distributed-systems

Research direction

Start with GrainCallCancellationManager.PumpCancellationQueue (Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:197), where the 30-second CancelCallsAsync timeout surfaces, then trace the silo shutdown and deactivation path to see whether queued cancellations for a departing silo are drained or kept firing. Done means establishing whether the timeouts come from undrained shutdowns or from busy silos, using the pod lifecycle around the listed timestamps. The issue has no agreed fix and the framework source is not in this repository, so this needs maintainer input before any change.

Written by the indexing model from the issue text.

Description

bug sev:M

What is failing

Orleans' distributed grain-call cancellation propagation. GrainCallCancellationManager.PumpCancellationQueue batches pending GrainCallCancellationRequests per target silo and delivers them via CancelCallsAsync to the remote silo's canceler system target (sys.svc.canceler). The remote call hits the 30-second response timeout, so a batch of cancellation requests is not delivered and the pump logs an error.

Probable cause

Medium confidence — target silos became unreachable, most likely due to silo shutdown/scale-down without draining the cancellation queue. Evidence: five of the six 2026-10-07 samples fire within 40 seconds from three different pods, all targeting the same silo (S10.244.2.27:11111:150368365) — a cluster-wide inability to reach one silo, not random load. The 2026-10-09 sample (on a newer portal replicaset) targets a different silo (S10.244.17.110:11111:150582958), so the pattern recurs on silo identity changes typical of deploy/scale events. The alternative — the target silo alive but too stalled to service a system-target call within 30s — is not supported by the simultaneity of the 10-07 burst, but can't be ruled out without pod logs for the target silos.

Impact

Low-to-moderate, judged from the numbers: 7 occurrences over ~2.5 days across 4 pods (two replicasets). Secondary path — the consequence is that grain-call cancellations queued for the affected silo are not propagated remotely, so in-flight calls on the target silo run to completion instead of being cancelled. No evidence of data loss or user-facing failure. However, each timeout also burns the 30s response window, and if the cause is an undrained shutdown rather than a dead silo, it will recur on every deploy.

Where to look

  • Orleans.Runtime.Cancellation.GrainCallCancellationManager.PumpCancellationQueue — the timeout surfaces at ResponseCompletionSource.GetResult waiting on the CancelCallsAsync request (framework source not present in this mesh; upstream path /_/src/Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:197).
  • The silo shutdown/deactivation path: does it stop delivering cancellation work queued for a silo that is leaving the cluster, or does the pump keep firing at a dead address until the membership table updates?
  • Check pod lifecycle for silos 10.244.2.27 around 2026-10-07 09:54 UTC and 10.244.17.110 around 2026-10-09 20:39 UTC to confirm they were shutting down (deploy/scale-down) at the time of the bursts.

Severity is a judgement call on intermittent evidence — re-rule if investigation shows the target silos were simply busy rather than departing (which would raise it) or if this only ever fires during expected rollouts (which would lower it to noise).

Evidence
Fingerprint 97b80f6a91dbdb74
Category Orleans.Runtime.GrainCallCancellationManager
Severity Error
Exception System.TimeoutException
Namespace memex-cloud
Pods memex-portal-deployment-748f7f4577-d92xf, memex-portal-deployment-748f7f4577-tp7b6, memex-portal-deployment-748f7f4577-pjrjp, memex-portal-deployment-845898d964-f6wm5
Occurrences 7
First seen 2026-10-07 09:54:09Z
Last seen 2026-10-09 20:39:03Z
Routing not determined — no configured route matches the category Orleans.Runtime.GrainCallCancellationManager. 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 
2026-10-07 09:54:09Z memex-portal-deployment-748f7f4577-tp7b6 fail: Orleans.Runtime.GrainCallCancellationManager[294010709]
      Error while cancelling 1 requests to S10.244.2.27:11111:150368365
      System.TimeoutException: Response did not arrive on time in 00:00:30 for message: Request [S10.244.6.61:11111:150368520 sys.svc.canceler/10.244.6.61:11111@150368520]->[S10.244.2.27:11111:150368365 sys.svc.canceler/10.244.2.27:11111@150368365] Orleans.Runtime.IGrainCallCancellationManagerSystemTarget.CancelCallsAsync(System.Collections.Generic.List`1[Orleans.Runtime.GrainCallCancellationRequest], System.Threading.CancellationToken) #22FE53E4E8A70120. 
         at Orleans.Serialization.Invocation.ResponseCompletionSource.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token) in /_/src/Orleans.Serialization/Invocation/ResponseCompletionSource.cs:line 100
         at Orleans.Runtime.GrainCallCancellationManager.PumpCancellationQueue(SiloAddress targetSilo, Channel`1 workItems, CancellationToken cancellationToken) in /_/src/Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:line 197
2026-10-07 09:54:09Z memex-portal-deployment-748f7f4577-pjrjp fail: Orleans.Runtime.GrainCallCancellationManager[294010709]
      Error while cancelling 1 requests to S10.244.2.27:11111:150368365
      System.TimeoutException: Response did not arrive on time in 00:00:30 for message: Request [S10.244.5.215:11111:150368445 sys.svc.canceler/10.244.5.215:11111@150368445]->[S10.244.2.27:11111:150368365 sys.svc.canceler/10.244.2.27:11111@150368365] Orleans.Runtime.IGrainCallCancellationManagerSystemTarget.CancelCallsAsync(System.Collections.Generic.List`1[Orleans.Runtime.GrainCallCancellationRequest], System.Threading.CancellationToken) #0738373D83D3E7F8. 
         at Orleans.Serialization.Invocation.ResponseCompletionSource.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token) in /_/src/Orleans.Serialization/Invocation/ResponseCompletionSource.cs:line 100
         at Orleans.Runtime.GrainCallCancellationManager.PumpCancellationQueue(SiloAddress targetSilo, Channel`1 workItems, CancellationToken cancellationToken) in /_/src/Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:line 197
2026-10-07 09:54:45Z memex-portal-deployment-748f7f4577-d92xf fail: Orleans.Runtime.GrainCallCancellationManager[294010709]
      Error while cancelling 6 requests to S10.244.2.27:11111:150368365
      System.TimeoutException: Response did not arrive on time in 00:00:30 for message: Request [S10.244.17.168:11111:150370762 sys.svc.canceler/10.244.17.168:11111@150370762]->[S10.244.2.27:11111:150368365 sys.svc.canceler/10.244.2.27:11111@150368365] Orleans.Runtime.IGrainCallCancellationManagerSystemTarget.CancelCallsAsync(System.Collections.Generic.List`1[Orleans.Runtime.GrainCallCancellationRequest], System.Threading.CancellationToken) #05EEB5647CB1E29E. 
         at Orleans.Serialization.Invocation.ResponseCompletionSource.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token) in /_/src/Orleans.Serialization/Invocation/ResponseCompletionSource.cs:line 100
         at Orleans.Runtime.GrainCallCancellationManager.PumpCancellationQueue(SiloAddress targetSilo, Channel`1 workItems, CancellationToken cancellationToken) in /_/src/Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:line 197
2026-10-07 09:54:45Z memex-portal-deployment-748f7f4577-tp7b6 fail: Orleans.Runtime.GrainCallCancellationManager[294010709]
      Error while cancelling 4 requests to S10.244.2.27:11111:150368365
      System.TimeoutException: Response did not arrive on time in 00:00:30 for message: Request [S10.244.6.61:11111:150368520 sys.svc.canceler/10.244.6.61:11111@150368520]->[S10.244.2.27:11111:150368365 sys.svc.canceler/10.244.2.27:11111@150368365] Orleans.Runtime.IGrainCallCancellationManagerSystemTarget.CancelCallsAsync(System.Collections.Generic.List`1[Orleans.Runtime.GrainCallCancellationRequest], System.Threading.CancellationToken) #22FE53E4E8A7D613. 
         at Orleans.Serialization.Invocation.ResponseCompletionSource.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token) in /_/src/Orleans.Serialization/Invocation/ResponseCompletionSource.cs:line 100
         at Orleans.Runtime.GrainCallCancellationManager.PumpCancellationQueue(SiloAddress targetSilo, Channel`1 workItems, CancellationToken cancellationToken) in /_/src/Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:line 197
2026-10-07 09:54:45Z memex-portal-deployment-748f7f4577-pjrjp fail: Orleans.Runtime.GrainCallCancellationManager[294010709]
      Error while cancelling 5 requests to S10.244.2.27:11111:150368365
      System.TimeoutException: Response did not arrive on time in 00:00:30 for message: Request [S10.244.5.215:11111:150368445 sys.svc.canceler/10.244.5.215:11111@150368445]->[S10.244.2.27:11111:150368365 sys.svc.canceler/10.244.2.27:11111@150368365] Orleans.Runtime.IGrainCallCancellationManagerSystemTarget.CancelCallsAsync(System.Collections.Generic.List`1[Orleans.Runtime.GrainCallCancellationRequest], System.Threading.CancellationToken) #0738373D83D30771. 
         at Orleans.Serialization.Invocation.ResponseCompletionSource.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token) in /_/src/Orleans.Serialization/Invocation/ResponseCompletionSource.cs:line 100
         at Orleans.Runtime.GrainCallCancellationManager.PumpCancellationQueue(SiloAddress targetSilo, Channel`1 workItems, CancellationToken cancellationToken) in /_/src/Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:line 197
2026-10-09 20:39:03Z memex-portal-deployment-845898d964-f6wm5 fail: Orleans.Runtime.GrainCallCancellationManager[294010709]
      Error while cancelling 1 requests to S10.244.17.110:11111:150582958
      System.TimeoutException: Response did not arrive on time in 00:00:30 for message: Request [S10.244.3.225:11111:150580999 sys.svc.canceler/10.244.3.225:11111@150580999]->[S10.244.17.110:11111:150582958 sys.svc.canceler/10.244.17.110:11111@150582958] Orleans.Runtime.IGrainCallCancellationManagerSystemTarget.CancelCallsAsync(System.Collections.Generic.List`1[Orleans.Runtime.GrainCallCancellationRequest], System.Threading.CancellationToken) #5BFE9C6F386D273A. 
         at Orleans.Serialization.Invocation.ResponseCompletionSource.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token) in /_/src/Orleans.Serialization/Invocation/ResponseCompletionSource.cs:line 100
         at Orleans.Runtime.GrainCallCancellationManager.PumpCancellationQueue(SiloAddress targetSilo, Channel`1 workItems, CancellationToken cancellationToken) in /_/src/Orleans.Runtime/Cancellation/GrainCallCancellationManager.cs:line 197

Opened automatically from Admin/_LogIncident/97b80f6a91dbdb74. Recurrences are folded into this issue rather than opening new ones.
It also stands for the whole log site c3ebae76cbeecea6: other fingerprints of this site fold in here as comments rather than opening tickets of their own.

Dominant language
C#
Stars
12
Forks
5
Avg merge
4h 19m
Merged PRs (30d)
932

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