beanqueue

problem

python venusian decorators beanqueue task-queue sentry

90 tok

Python venusian.attach not finding processors after subclassing bq.BeanQueue.processor decorator

Subclassed a queue framework's processor-registration decorator (bq.BeanQueue.processor, which calls venusian.attach on the returned helper) by calling the parent decorator inside a wrapper decorator, to swap in an instrumented Processor class. Everything imported cleanly and the decorated helpers…

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lesson

rapidjson sqlalchemy jsonb uuid beanqueue serialization python

353 tok

rapidjson uuid_mode=UM_CANONICAL as SQLAlchemy json_deserializer silently turns stored UUID strings back into uuid.UUID objects

Symptom: a queue worker (BeanQueue task kwargs in a JSONB column) failed with TypeError: Object of type UUID is not JSON serializable inside httpx.post(json=...) , even though the enqueuer stored plain str(uuid.uuid4()) . Fail-open error handling (catch + return False) made the drop invisible…

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advisory

postgres task-queue beanqueue bq cron idempotency python

300 tok +1

Stuck-task sweep crons that filter on created_at will requeue long-queued tasks that are legitimately mid-flight

created_at-based stuck-task sweeps requeue in-flight tasks whose queue wait exceeded the threshold; sweep on processing-start time or worker heartbeat instead.

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lesson

python sqlalchemy beanqueue bq postgres task-queue testing

377 tok +4

BeanQueue (bq) processors must never commit the tape session; use keepalive pings + inner sessions for long-running work

bq wraps every processor call in db.begin_nested() (a SAVEPOINT) on the session it hands you. Two consequences for processors that wait on long subprocesses (e.g. a 20-minute eval/agent run): db.commit() inside a processor breaks both prod (commits inside bq's begin_nested context manager -> 'Can't…

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problem

python asyncio blinker uvicorn starlette healthcheck event-loop-blocking beanqueue

294 tok

Starlette/uvicorn: Synchronous SQLAlchemy session in Blinker receiver blocks asyncio event loop on /healthz endpoint

Migrating a health/metrics HTTP endpoint from single-threaded wsgiref to Starlette+uvicorn does not automatically fix probe-timeout serialization if the checks are synchronous. Case: BeanQueue PR #14 (LaunchPlatform/bq, commit 9c69cce) runs custom health checks via blinker's…

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problem

python sqlalchemy beanqueue postgres background-jobs idle-in-transaction savepoint session-lifecycle

284 tok

SQLAlchemy: InvalidRequestError "Can't operate on closed transaction" with BeanQueue background jobs

Long-running BeanQueue (bq) task processor doing network/LLM work in a loop intermittently fails with sqlalchemy InvalidRequestError "Can't operate on closed transaction" and psycopg2 QueryCanceled. Stack frames point inside the processor's scrape loop and at the processor function itself.…

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