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feat(uptime): Add ability to use queues to manage parallelism #7
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,345 @@ | ||
| from __future__ import annotations | ||
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| import logging | ||
| import queue | ||
| import threading | ||
| import time | ||
| from collections import defaultdict | ||
| from collections.abc import Callable | ||
| from dataclasses import dataclass | ||
| from typing import Any, Generic, TypeVar | ||
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| import sentry_sdk | ||
| from arroyo.backends.kafka.consumer import KafkaPayload | ||
| from arroyo.processing.strategies import ProcessingStrategy | ||
| from arroyo.types import BrokerValue, FilteredPayload, Message, Partition | ||
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| from sentry.utils import metrics | ||
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| logger = logging.getLogger(__name__) | ||
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| T = TypeVar("T") | ||
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| @dataclass | ||
| class WorkItem(Generic[T]): | ||
| """Work item that includes the original message for offset tracking.""" | ||
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| partition: Partition | ||
| offset: int | ||
| result: T | ||
| message: Message[KafkaPayload | FilteredPayload] | ||
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| class OffsetTracker: | ||
| """ | ||
| Tracks outstanding offsets and determines which offsets are safe to commit. | ||
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| - Tracks offsets per partition | ||
| - Only commits offsets when all prior offsets are processed | ||
| - Thread-safe for concurrent access with per-partition locks | ||
| """ | ||
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| def __init__(self) -> None: | ||
| self.all_offsets: dict[Partition, set[int]] = defaultdict(set) | ||
| self.outstanding: dict[Partition, set[int]] = defaultdict(set) | ||
| self.last_committed: dict[Partition, int] = {} | ||
| self.partition_locks: dict[Partition, threading.Lock] = {} | ||
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| def _get_partition_lock(self, partition: Partition) -> threading.Lock: | ||
| """Get or create a lock for a partition.""" | ||
| lock = self.partition_locks.get(partition) | ||
| if lock: | ||
| return lock | ||
| return self.partition_locks.setdefault(partition, threading.Lock()) | ||
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| def add_offset(self, partition: Partition, offset: int) -> None: | ||
| """Record that we've started processing an offset.""" | ||
| with self._get_partition_lock(partition): | ||
| self.all_offsets[partition].add(offset) | ||
| self.outstanding[partition].add(offset) | ||
|
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| def complete_offset(self, partition: Partition, offset: int) -> None: | ||
| """Mark an offset as completed.""" | ||
| with self._get_partition_lock(partition): | ||
| self.outstanding[partition].discard(offset) | ||
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| def get_committable_offsets(self) -> dict[Partition, int]: | ||
| """ | ||
| Get the highest offset per partition that can be safely committed. | ||
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| For each partition, finds the highest contiguous offset that has been processed. | ||
| """ | ||
| committable = {} | ||
| for partition in list(self.all_offsets.keys()): | ||
| with self._get_partition_lock(partition): | ||
| all_offsets = self.all_offsets[partition] | ||
| if not all_offsets: | ||
| continue | ||
|
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| outstanding = self.outstanding[partition] | ||
| last_committed = self.last_committed.get(partition, -1) | ||
|
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| min_offset = min(all_offsets) | ||
| max_offset = max(all_offsets) | ||
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| start = max(last_committed + 1, min_offset) | ||
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| highest_committable = last_committed | ||
| for offset in range(start, max_offset + 1): | ||
| if offset in all_offsets and offset not in outstanding: | ||
| highest_committable = offset | ||
| else: | ||
| break | ||
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| if highest_committable > last_committed: | ||
| committable[partition] = highest_committable | ||
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| return committable | ||
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| def mark_committed(self, partition: Partition, offset: int) -> None: | ||
| """Update the last committed offset for a partition.""" | ||
| with self._get_partition_lock(partition): | ||
| self.last_committed[partition] = offset | ||
| # Remove all offsets <= committed offset | ||
| self.all_offsets[partition] = {o for o in self.all_offsets[partition] if o > offset} | ||
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| class OrderedQueueWorker(threading.Thread, Generic[T]): | ||
| """Worker thread that processes items from a queue in order.""" | ||
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| def __init__( | ||
| self, | ||
| worker_id: int, | ||
| work_queue: queue.Queue[WorkItem[T]], | ||
| result_processor: Callable[[str, T], None], | ||
| identifier: str, | ||
| offset_tracker: OffsetTracker, | ||
| ) -> None: | ||
| super().__init__(daemon=True) | ||
| self.worker_id = worker_id | ||
| self.work_queue = work_queue | ||
| self.result_processor = result_processor | ||
| self.identifier = identifier | ||
| self.offset_tracker = offset_tracker | ||
| self.shutdown = False | ||
|
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| def run(self) -> None: | ||
| """Process items from the queue in order.""" | ||
| while not self.shutdown: | ||
| try: | ||
| work_item = self.work_queue.get() | ||
| except queue.ShutDown: | ||
| break | ||
|
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||
| try: | ||
| with sentry_sdk.start_transaction( | ||
| op="queue_worker.process", | ||
| name=f"monitors.{self.identifier}.worker_{self.worker_id}", | ||
| ): | ||
| self.result_processor(self.identifier, work_item.result) | ||
|
|
||
| except queue.ShutDown: | ||
| break | ||
| except Exception: | ||
| logger.exception( | ||
| "Unexpected error in queue worker", extra={"worker_id": self.worker_id} | ||
| ) | ||
| finally: | ||
| self.offset_tracker.complete_offset(work_item.partition, work_item.offset) | ||
| metrics.gauge( | ||
| "remote_subscriptions.queue_worker.queue_depth", | ||
| self.work_queue.qsize(), | ||
| tags={ | ||
| "identifier": self.identifier, | ||
| }, | ||
| ) | ||
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| class FixedQueuePool(Generic[T]): | ||
| """ | ||
| Fixed pool of queues that guarantees order within groups. | ||
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| Key properties: | ||
| - Each group is consistently assigned to the same queue | ||
| - Each queue has exactly one worker thread | ||
| - Items within a queue are processed in FIFO order | ||
| - No dynamic reassignment that could break ordering | ||
| - Tracks offset completion for safe commits | ||
| """ | ||
|
|
||
| def __init__( | ||
| self, | ||
| result_processor: Callable[[str, T], None], | ||
| identifier: str, | ||
| num_queues: int = 20, | ||
| ) -> None: | ||
| self.result_processor = result_processor | ||
| self.identifier = identifier | ||
| self.num_queues = num_queues | ||
| self.offset_tracker = OffsetTracker() | ||
| self.queues: list[queue.Queue[WorkItem[T]]] = [] | ||
| self.workers: list[OrderedQueueWorker[T]] = [] | ||
|
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| for i in range(num_queues): | ||
| work_queue: queue.Queue[WorkItem[T]] = queue.Queue() | ||
| self.queues.append(work_queue) | ||
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| worker = OrderedQueueWorker[T]( | ||
| worker_id=i, | ||
| work_queue=work_queue, | ||
| result_processor=result_processor, | ||
| identifier=identifier, | ||
| offset_tracker=self.offset_tracker, | ||
| ) | ||
| worker.start() | ||
| self.workers.append(worker) | ||
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| def get_queue_for_group(self, group_key: str) -> int: | ||
| """ | ||
| Get queue index for a group using consistent hashing. | ||
| """ | ||
| return hash(group_key) % self.num_queues | ||
|
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| def submit(self, group_key: str, work_item: WorkItem[T]) -> None: | ||
| """ | ||
| Submit a work item to the appropriate queue. | ||
| """ | ||
| queue_index = self.get_queue_for_group(group_key) | ||
| work_queue = self.queues[queue_index] | ||
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| self.offset_tracker.add_offset(work_item.partition, work_item.offset) | ||
| work_queue.put(work_item) | ||
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| def get_stats(self) -> dict[str, Any]: | ||
| """Get statistics about queue depths.""" | ||
| queue_depths = [q.qsize() for q in self.queues] | ||
| return { | ||
| "queue_depths": queue_depths, | ||
| "total_items": sum(queue_depths), | ||
| } | ||
|
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| def wait_until_empty(self, timeout: float = 5.0) -> bool: | ||
| """Wait until all queues are empty. Returns True if successful, False if timeout.""" | ||
| start_time = time.time() | ||
| while time.time() - start_time < timeout: | ||
| if self.get_stats()["total_items"] == 0: | ||
| return True | ||
| time.sleep(0.01) | ||
| return False | ||
|
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| def shutdown(self) -> None: | ||
| """Gracefully shutdown all workers.""" | ||
| for worker in self.workers: | ||
| worker.shutdown = True | ||
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| for q in self.queues: | ||
| try: | ||
| q.shutdown(immediate=False) | ||
| except Exception: | ||
| logger.exception("Error shutting down queue") | ||
|
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| for worker in self.workers: | ||
| worker.join(timeout=5.0) | ||
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| class SimpleQueueProcessingStrategy(ProcessingStrategy[KafkaPayload], Generic[T]): | ||
| """ | ||
| Processing strategy that uses a fixed pool of queues. | ||
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| Guarantees: | ||
| - Items for the same group are processed in order | ||
| - No item is lost or processed out of order | ||
| - Natural backpressure when queues fill up | ||
| - Only commits offsets after successful processing | ||
| """ | ||
|
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| def __init__( | ||
| self, | ||
| queue_pool: FixedQueuePool[T], | ||
| decoder: Callable[[KafkaPayload | FilteredPayload], T | None], | ||
| grouping_fn: Callable[[T], str], | ||
| commit_function: Callable[[dict[Partition, int]], None], | ||
| ) -> None: | ||
| self.queue_pool = queue_pool | ||
| self.decoder = decoder | ||
| self.grouping_fn = grouping_fn | ||
| self.commit_function = commit_function | ||
| self.shutdown_event = threading.Event() | ||
|
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| self.commit_thread = threading.Thread(target=self._commit_loop, daemon=True) | ||
| self.commit_thread.start() | ||
|
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| def _commit_loop(self) -> None: | ||
| while not self.shutdown_event.is_set(): | ||
| try: | ||
| self.shutdown_event.wait(1.0) | ||
|
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| committable = self.queue_pool.offset_tracker.get_committable_offsets() | ||
|
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| if committable: | ||
| metrics.incr( | ||
| "remote_subscriptions.queue_pool.offsets_committed", | ||
| len(committable), | ||
| tags={"identifier": self.queue_pool.identifier}, | ||
| ) | ||
|
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| self.commit_function(committable) | ||
| for partition, offset in committable.items(): | ||
| self.queue_pool.offset_tracker.mark_committed(partition, offset) | ||
| except Exception: | ||
| logger.exception("Error in commit loop") | ||
|
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| def submit(self, message: Message[KafkaPayload | FilteredPayload]) -> None: | ||
| try: | ||
| result = self.decoder(message.payload) | ||
|
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| assert isinstance(message.value, BrokerValue) | ||
| partition = message.value.partition | ||
| offset = message.value.offset | ||
|
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| if result is None: | ||
| self.queue_pool.offset_tracker.add_offset(partition, offset) | ||
| self.queue_pool.offset_tracker.complete_offset(partition, offset) | ||
| return | ||
|
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| group_key = self.grouping_fn(result) | ||
|
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| work_item = WorkItem( | ||
| partition=partition, | ||
| offset=offset, | ||
| result=result, | ||
| message=message, | ||
| ) | ||
|
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| self.queue_pool.submit(group_key, work_item) | ||
|
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| except Exception: | ||
| logger.exception("Error submitting message to queue") | ||
| if isinstance(message.value, BrokerValue): | ||
| self.queue_pool.offset_tracker.add_offset( | ||
| message.value.partition, message.value.offset | ||
| ) | ||
| self.queue_pool.offset_tracker.complete_offset( | ||
| message.value.partition, message.value.offset | ||
| ) | ||
|
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| def poll(self) -> None: | ||
| stats = self.queue_pool.get_stats() | ||
| metrics.gauge( | ||
| "remote_subscriptions.queue_pool.total_queued", | ||
| stats["total_items"], | ||
| tags={"identifier": self.queue_pool.identifier}, | ||
| ) | ||
|
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| def close(self) -> None: | ||
| self.shutdown_event.set() | ||
| self.commit_thread.join(timeout=5.0) | ||
| self.queue_pool.shutdown() | ||
|
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| def terminate(self) -> None: | ||
| self.shutdown_event.set() | ||
| self.queue_pool.shutdown() | ||
|
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| def join(self, timeout: float | None = None) -> None: | ||
| self.close() | ||
|
Comment on lines
+246
to
+345
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. 🛠️ Refactor suggestion | 🟠 Major Align SimpleQueueProcessingStrategy lifecycle with factory ownership of the pool and quiet the unused timeout arg. Given def close(self) -> None:
- self.shutdown_event.set()
- self.commit_thread.join(timeout=5.0)
- self.queue_pool.shutdown()
+ self.shutdown_event.set()
+ self.commit_thread.join(timeout=5.0)
def terminate(self) -> None:
- self.shutdown_event.set()
- self.queue_pool.shutdown()
+ self.shutdown_event.set()
def join(self, timeout: float | None = None) -> None:
- self.close()
+ # `timeout` is unused; we always wait up to 5s in `close`.
+ self.close()In the queue-consumer tests, you can then explicitly call This prevents the pool from being torn down during a rebalance (when only the strategy is closed), and it resolves the double-shutdown behavior once the factory also calls 🧰 Tools🪛 Ruff (0.14.5)344-344: Unused method argument: (ARG002) 🤖 Prompt for AI Agents |
||
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🧩 Analysis chain
Queue worker shutdown and error semantics are broken; fix
queue.ShutDownusage and only mark successful items complete.Two issues here:
queueas if it had aShutDownexception andQueue.shutdown()method. Those do not exist onqueue.Queue, soFixedQueuePool.shutdown()will log exceptions for each queue andOrderedQueueWorker.run()will never break out on shutdown.OrderedQueueWorker.run()always callsoffset_tracker.complete_offsetinfinally, even whenresult_processorraises, which makes failed items look successfully processed to the commit loop.A concrete fix using
queue.Emptyand a success flag:This:
queue.Emptywith a short timeout to allow workers to exit onceshutdownis set.queue.ShutDown/Queue.shutdown.Also applies to: 231-244
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I'll verify the issues by examining the actual code and test coverage.
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Let me check for error handling tests and the OffsetTracker implementation:
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Fix non-existent queue.ShutDown exception, Queue.shutdown() method, and offset completion semantics.
All three issues are confirmed:
queue.ShutDown exception doesn't exist: Lines 132 and 143 attempt to catch a non-existent exception. Python's stdlib
queuemodule has noShutDownexception, so these handlers will never trigger and workers won't exit cleanly on shutdown.Queue.shutdown() method doesn't exist: Line 238 calls
q.shutdown(immediate=False), which doesn't exist onqueue.Queue. The call is caught by the genericExceptionhandler and logged, but the shutdown is ineffective.Failed items marked complete unconditionally: Line 149 calls
offset_tracker.complete_offsetin thefinallyblock even whenresult_processor(line 146) raises an exception. This masks processing failures and creates offset gaps that appear to block commits, contrary to the intended semantics of only marking successful items complete.The review's suggested fix using
queue.Emptywith a timeout and asuccessflag is correct and aligns with the offset gap-based commit strategy shown intest_offset_gaps_block_commits.