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Both Cloud Tasks and
Pub/Sub may be used to
implement message passing and asynchronous integration, but while they
function in similar ways, they are not identical. This page helps you choose the
right product for your use case.
Key Differences
The core difference between Pub/Sub and Cloud Tasks is the
notion of implicit vs explicit invocation.
Pub/Sub aims to decouple publishers of events and subscribers to those
events. Publishers do not need to know anything about their subscribers. As a result,
Pub/Sub gives publishers no control over the delivery of the messages save for
the guarantee of delivery. In this way, Pub/Sub supports implicit invocation:
a publisher implicitly causes the subscribers to execute by publishing an event.
By contrast, Cloud Tasks is aimed at explicit invocation where the publisher
retains full control of execution. In particular, a publisher specifies an
endpoint where each message is to be delivered.
In addition, Cloud Tasks provides tools for queue and
task management unavailable to Pub/Sub publishers, including:
Scheduling specific delivery times
Delivery rate controls
Configurable retries
Access and management of individual tasks in a queue
Task/message creation deduplication
Detailed feature comparison
Feature
Cloud Tasks
Cloud Pub/Sub
Push via webhooks
Yes
Yes
At least once delivery guarantee
Yes
Yes
Configurable retries
Yes
Yes
Task creation deduplication
Yes
No
Scheduled delivery
Yes
No
Ordered delivery
No. Enqueued task order is preserved on best-effort basis.
Yes with ordering keys
Explicit rate controls
Yes
Pull subscriber clients can implement flow control
Pull via API
No
Yes
Batch insert
No
Yes
Multiple handlers/subscribers per message
No
Yes
Task/message retention
30 days
Up to 31 days
Max size of task/message
1MB
10MB
Max delivery rate
500 qps/queue
No upper limit
Geographic availability
Regional
Global
Maximum push handler/subscriber processing duration
30 minutes (HTTP)
10 minutes (App Engine Standard automatic scaling)
24 hours (App Engine Standard manual or basic scaling)
60 minutes (App Engine Flexible)
10 minutes for push operations
Number of queues/subscriptions per project
1,000/project, more available via quota increase request
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[],[],null,["# Choose Cloud Tasks or Pub/Sub\n\nBoth [Cloud Tasks](/tasks/docs/dual-overview) and\n[Pub/Sub](/pubsub/docs/overview) may be used to\nimplement message passing and asynchronous integration, but while they\nfunction in similar ways, they are not identical. This page helps you choose the\nright product for your use case.\n\nKey Differences\n---------------\n\nThe core difference between Pub/Sub and Cloud Tasks is the\nnotion of implicit vs explicit invocation.\n\nPub/Sub aims to decouple publishers of events and subscribers to those\nevents. Publishers do not need to know anything about their subscribers. As a result,\nPub/Sub gives publishers no control over the delivery of the messages save for\nthe guarantee of delivery. In this way, Pub/Sub supports **implicit** invocation:\na publisher implicitly causes the subscribers to execute by publishing an event.\n\nBy contrast, Cloud Tasks is aimed at **explicit** invocation where the publisher\nretains full control of execution. In particular, a publisher specifies an\nendpoint where each message is to be delivered.\n\nIn addition, Cloud Tasks provides tools for queue and\ntask management unavailable to Pub/Sub publishers, including:\n\n- Scheduling specific delivery times\n- Delivery rate controls\n- Configurable retries\n- Access and management of individual tasks in a queue\n- Task/message creation deduplication\n\nDetailed feature comparison\n---------------------------"]]
