Delayed operations with queues for website performance
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The document discusses the use of queues in Drupal to enhance website performance, enabling faster visitor experiences and more scalable processing of time-consuming jobs. It covers various applications such as content preparation, slow operations handling, and job monitoring, while detailing the queue API, its concepts, and limitations. Additionally, it highlights different queue implementations and the importance of effective job management techniques.
![D6/D7 Queue API
D7: core
D6: drupal_queue module
Declaring queues:
hook_cron_queue_info[_alter]()
● “Skip on cron”: enable decoupling from cron runs
● Time: max lifetime allocated to process items
during a cron run, useless with skip on cron =
TRUE
● Worker callback: an implementation of
callback_queue_worker (mixed
queue_item): void
API useable without cron
Default Runner:
● In the cron subsystem
● Pokemon exception handling](https://image.slidesharecdn.com/delayed-operations-151003190311-lva1-app6891/85/Delayed-operations-with-queues-for-website-performance-17-320.jpg)
![Queue API methods: Queue
QueueInterface
● Q::createItem(mixed $data: void
● Q::claimItem($lease_time = 3600: mixed $item
○ FALSE | stdClass + [item_id => int, data => mixed, created => timestamp]
○ $lease_time → Assumptions for runner, currently not used
● Q::deleteItem($item): void -> work done
● Q::releaseItem($item): bool
● Q::numberOfItems(): int → best guess, unreliable
● Q::createQueue() / Q::deleteQueue()
ReliableQueueInterface: ordering, single execution](https://image.slidesharecdn.com/delayed-operations-151003190311-lva1-app6891/85/Delayed-operations-with-queues-for-website-performance-19-320.jpg)
Delayed operations with queues for website performance
- 2. Delayed operations with queues Yuriy Gerasimov Frédéric G. Marand Session track: PHP
- 3. Who are we?
- 4. Yuriy Gerasimov ● FFW ● Drupal architect & developer ● Contrib 7 modules: services, draggableviews ● Founder at Backtrac.io ygerasimov
- 5. Frédéric G. Marand ● OSInet: performance/architecture consulting for internal teams at larger accounts ● Core contributor 4.7 to 8.0.x, MongoDB + XMLRPC maintainer + others ● Already 4 D8 customer projects before 8.0.0 ● Customer D8 in production since 07/2015 ● Frequently adds queueing to larger Drupal projects fgm
- 6. Why use queues ? To have websites which are : ● Faster for visitors ● Snappier for editors ● More scaleable To process time-consuming jobs : ● Video encoding ● High-resolution gallery uploads and processing
- 7. Concrete use cases ● Prepare content for non-Drupal front-ends ● Anticipate content generation ● Deferred submits, e.g. comments handling ● Slow operations: node saves, previews, image processing ● External data sources: pull, push ● Multi-step operations: batch
- 9. Anticipated content generation Blocks Ctools content types Controllers etc. Contrib : http://github.com/FGM/lazy Content created Served from cache Fresh Stale Expiredt0 t1 t2 Served from cache Regenerate cache time Usual Drupal Content created Served from cache Fresh Stale Fresht0 t1 t2 Served from cache + request update Store Served from cache time Anticipated content generation
- 10. Comment handling
- 11. “Pull” data sources (aggregator)
- 13. Image processing
- 14. Job servers ● How to get results ● Rerun failed jobs ● Separate queue for failed jobs ● Monitoring queues, workers ● Supervisor
- 15. Some implementations Queue D6 D7 D8 Memory core core Database OK core core AdvancedQueue OK Not yet Amazon SQS (aws_sqs) OK Not yet Beanstalkd OK 8.1/8.2 evQueue Started Queue D6 D7 D8 IronMQ (iron.io) OK Not yet Gearman OK OK Not yet MongoDB OK Started PHPResque RabbitMQ OK Not yet Redis (redis_queue) OK OK Not yet
- 16. Queues API: concepts Queue: a minimally-featured FIFO Worker: the code actually doing the work Item: a piece of workload submitted to the queue Runner: the process triggering/monitoring workers Batch subsystem: a high-level API on top of Queue API D8: Manager, Plugins
- 17. D6/D7 Queue API D7: core D6: drupal_queue module Declaring queues: hook_cron_queue_info[_alter]() ● “Skip on cron”: enable decoupling from cron runs ● Time: max lifetime allocated to process items during a cron run, useless with skip on cron = TRUE ● Worker callback: an implementation of callback_queue_worker (mixed queue_item): void API useable without cron Default Runner: ● In the cron subsystem ● Pokemon exception handling
- 18. D8 Queue API API useable without cron Declaring queue workers: Service: plugin.manager.queue_worker Instantiates QueueWorker plugins Definition: ● Cron, not enabled by default ○ Time: max lifetime allocated to process items during a cron run ● Core examples : AggregatorRefresh, LocaleTranslation ● hook_queue_info_alter() Default Runner: In the cron subsystem: DrupalCoreCron::processQueues() SuspendQueueException: $q- >releaseItem()
- 19. Queue API methods: Queue QueueInterface ● Q::createItem(mixed $data: void ● Q::claimItem($lease_time = 3600: mixed $item ○ FALSE | stdClass + [item_id => int, data => mixed, created => timestamp] ○ $lease_time → Assumptions for runner, currently not used ● Q::deleteItem($item): void -> work done ● Q::releaseItem($item): bool ● Q::numberOfItems(): int → best guess, unreliable ● Q::createQueue() / Q::deleteQueue() ReliableQueueInterface: ordering, single execution
- 20. Queue API methods: others Queue service → QueueFactory::get($name, $reliable) QueueManager: a vanilla plugin manager ● In charge of hook_queue_info_alter() ● createInstance($plugin_id, $configuration) QueueWorkerInterface: ● processItem (mixed data) : void @throws SuspendQueueException
- 21. Queue Runners Core / Contrib ● Core Cron / Elysia Cron / Queue_Runner ● Drush: queue-list / queue-run ● Similar limitations: ○ Default on in D6 / D7, default off in D8 ○ Limited timeout support: non preemptive ○ Single threaded, single process across queues Custom runners ● Provided by queue modules or per-project one-offs ● Preemption, parallel execution...
- 22. Queue API limitations Limited FIFO paradigm ● D8: non-Reliable QueueInterface: datagram No monitoring No queue disciplines ● Priority management ● Tagging ● Delay, burying ... Implementations may provide more ● Item structure is free-form: add richer interfaces No Peek(), no LIFO, no deduplication: hacks
- 23. Performance edge Runners: ● Avoid active polling à la core DB ● Use a blocking layer + select() ● Parallel handling of multiple queues → multiple runners, scheduling Workers: read after write ● Write in the queue → cache invalidated ● Read again→ cache primed
- 24. Sprint: Friday https://www.flickr. com/photos/amazeelabs/9965814443/in/fav es-38914559@N03/ Sprint with the Community on Friday. We have tasks for every skillset. Mentors are available for new contributors. An optional Friday morning workshop for first- time sprinters will help you get set up. Follow @drupalmentoring.