Add delay in subscriber loop to prevent tight retry on error #1904
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pkg/gofr/subscriber.go
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| var delay time.duration = 2 * time.second | ||
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| for { | ||
| select { | ||
| case <-ctx.Done(): | ||
| s.container.Logger.Infof("shutting down subscriber for topic %s", topic) | ||
| return nil | ||
| default: | ||
| case <-time.after(delay): |
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I don't understand this change. When the app starts it now wait 2s ?
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You're right -with the current change, the subscriber waits 2 seconds even on the first run, which is not ideal.
I'll fix it by keeping the first attempt immediate and only applying the delay after an error occurs.
I'll move the delay logic inside the error block, and restore default: for the initial trigger.
default: case to ensure no delay on first attempt. However, there’s still one final thing missing: the actual delay (sleep) call after an error.
@bhagavan04 Thankyou for your contribution i found your code still have some linter errors. Please resolve the same. The examples are not even working right now for testing your change. |
Key error to fix Incorrect. time.Second and time .Sleep() is capitalized because it's a constant in the time package
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Hey @bhagavan04 |
Fix all syntax issues (time.Second, time.After, etc.) Remove unused imports like math
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Fix all syntax issues (time.Second, time.After, etc.) |
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Do you mind adding a Co-authored-by tag to your commits ? Here is mine Some context here: https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/creating-a-commit-with-multiple-authors Thanks |
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"I've added the Co-authored-by tag. Please review and approve the workflows." |
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@bhagavan04 , There are Code quality issue. Check them out and fix them. |
@bhagavan04 Still this issue exists in Code Quality step.
Please resolve it. |
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@bhagavan04 The fix was tested, and the logs show that the delay mechanism in startSubscriber is not functioning as expected. While the delay is applied between loop iterations, it doesn't handle concurrent subscriptions to multiple topics properly. This results in errors being logged without the intended delays. 
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Thanks for the feedback @Umang01-hash! You're right — the delay logic inside startSubscriber currently applies only within a single loop execution per topic, and since subscriptions are launched concurrently per topic, retries across topics can still hammer the system tightly. Will push a patch shortly — happy to hear any other ideas too! |
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@bhagavan04 Any updates on the above? |
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@bhagavan04 , As there have been no updates fro your side, would be closing the PR for now. Feel free to reopen it after the comments above have been addressed. |
Fix: Add delay in startSubscriber loop to prevent tight retry on subscription error.
Description: This PR fixes a potential performance issue in the SubscriptionManager where the startSubscriber method retries immediately after a subscription failure without delay.
current behaviour: ->Immediate retry on subscription errors.
->Leads to high CPU usage and excessive logs during repeated failures
after fix behaviour: ->Added time.Sleep(2 * time.Second) after a failed subscription attempt
->Imported Go standard time package
->Improves resilience and prevents retry storm
Future enhancement: Make retry delay configurable via container or env.
Before Change (No Delay – Tight Loop):
log output:
ERROR error in subscription for topic user-events: connection refused
ERROR error in subscription for topic user-events: connection refused
ERROR error in subscription for topic user-events: connection refused
...
(CPU usage high, log flooding rapidly)
After Change (With Delay):
Log output
ERROR error in subscription for topic user-events: connection refused
(wait 2s)
ERROR error in subscription for topic user-events: connection refused
(wait 2s)
ERROR error in subscription for topic user-events: connection refused
...
(Much smoother, reduced load)