We are observing inconsistent and unexpected behavior between sync and async chat completion modes for the same query and model.
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In sync mode, the request completes successfully and returns the expected response in approximately 20 seconds.
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In async mode, the same request remains in
IN_PROGRESSstatus for an unusually long duration (2–3 hours), without failure or intermediate status updates. -
When the async request finally completes, the timestamps indicate that the actual execution time was approximately 1 minute, suggesting that the job was queued or stalled for hours before being executed.
Details
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Model:
sonar-deep-research -
Query: Same exact user query used in both sync and async modes
Sync Mode Result
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Status:
COMPLETED -
Response time: ~20 seconds
Async Mode Result
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Status:
IN_PROGRESSfor ~2–3 hours -
No failure or error reported during this period
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Eventually transitions to
COMPLETED
Key Observation (Important)
From the async job metadata:
"created_at": 1768991705,
"started_at": 1768991705,
"completed_at": 1768991768
This indicates:
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The async job completed in ~63 seconds
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However, the client observed the job in
IN_PROGRESSstate for multiple hours before this completion was surfaced
This suggests the async job may have been:
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Queued or delayed for an extended period before actual execution, or
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Executed earlier but completion status was not updated or returned promptly
Async Job State During Delay
During the extended delay:
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status:IN_PROGRESS -
completed_at:null -
failed_at:null -
error_message:null
No indication was provided that the job was queued, paused, or delayed.