fix(fcm): Optimize SendEachInBatch with worker pool
#695
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The `sendEachInBatch` function, used for sending FCM messages individually within a batch, previously created a new goroutine for each message. This could lead to high CPU usage for large batches. This commit refactors `sendEachInBatch` to use a fixed-size pool of concurrent operations (10 operations) to manage message sending. This limits the number of active goroutines, reducing CPU overhead and improving resource utilization. Key changes: - Implemented early validation: All messages are now validated upfront. If any message is invalid, the function returns an error immediately without attempting to send any messages. - Introduced a mechanism for managing concurrent operations: Manages a fixed number of goroutines to process message sending tasks. Messages are distributed via channels. - Ensured result ordering: The order of responses in `BatchResponse.Responses` correctly matches the order of the input messages, even with concurrent processing. - Updated unit tests in `messaging_batch_test.go` to comprehensively cover the new implementation, including scenarios for varying batch sizes, partial failures, early validation, and response ordering. - Confirmed that the existing HTTP client continues to leverage HTTP/2.
This commit increases the number of goroutines in the `sendEachInBatch` function from 10 to 50. This change is based on your feedback to potentially improve throughput for large batches of FCM messages. The number 50 was chosen as a significant increase over the previous conservative value of 10, aiming to provide better concurrency for I/O-bound operations without being excessively high. The goal is to allow for more parallel processing of messages up to the maximum batch limit of 500. Performance in specific environments should be monitored to ensure this change has the desired effect without causing undue resource strain. Unit tests in `messaging_batch_test.go` have been reviewed and adjusted to ensure they remain meaningful with the new pool size, particularly scenarios testing behavior when the number of messages is less than, equal to, or greater than the number of concurrent processes.
This commit addresses two issues introduced in previous changes: 1. A syntax error in `messaging/messaging_batch_test.go` caused by a duplicated `t.Run` call and associated redundant variable declarations. 2. An "imported and not used" error for the "sync" package in `messaging/messaging_batch.go`, which occurred after `sync.WaitGroup` was removed and the import statement was not. These fixes ensure the code builds cleanly and passes lint checks.
This commit re-adds the `import "sync"` statement to `messaging/messaging_batch_test.go`. The `sync` package, specifically `sync.Mutex`, is used within the test suite (e.g., in `TestSendEachWorkerPoolScenarios` and `TestSendEachResponseOrderWithConcurrency`) to protect shared variables like hit counters and logs from race conditions when accessed by concurrently running mock HTTP server handlers. A previous change inadvertently removed this import while cleaning up unused imports in other files, leading to "undefined: sync" build errors in the test file. This commit corrects that oversight.
This commit addresses several issues in the messaging test suite
(`messaging_batch_test.go`) that were causing test failures,
including data races and incorrect test logic:
1. **Data Races:**
* In `TestSendEachPartialFailure` and `TestSendEachTotalFailure`,
the `serverHitCount` variable in mock server handlers was accessed
concurrently without synchronization. This has been fixed by
introducing a `sync.Mutex` to protect access to `serverHitCount`
within each test case's server setup.
2. **Early Validation Test (`TestSendEachEarlyValidationSkipsSend`):**
* The `invalid_last_message` test was failing because the
type of invalidity used (large payload) was not caught by the
early `validateMessage` scan in `sendEachInBatch`.
* Fixed by changing the invalid message to one with both Topic and
Token defined, which `validateMessage` correctly flags, ensuring
the test now accurately verifies early exit behavior and that no
server calls are made.
3. **Partial Failure Scenario (`TestSendEachWorkerPoolScenarios`):**
* The test for partial failures
(`NumMessages_75_AllSuccess_false_...`) was failing due to a
mismatch between the mock server's failure simulation (based on
request arrival order) and the test's assertions (based on
original message index).
* Fixed by modifying the mock server to parse the original message
index from the message content (topic) and use this for
failure simulation, ensuring deterministic alignment with assertions.
These changes should ensure the stability and correctness of the
messaging batch processing tests, especially those verifying
concurrent operations and error handling.
I applied `gofmt -s .` to ensure consistent code formatting, particularly for `messaging/messaging_batch.go` and `messaging/messaging_batch_test.go`. This commit reflects any adjustments made by gofmt to align with standard Go formatting practices, including simplification of struct initializations and consistent spacing.
This commit applies gofmt formatting, with a specific focus on removing trailing whitespace from messaging/messaging_batch_test.go as identified by previous `gofmt -d` outputs. This is part of a series of fixes to ensure the codebase conforms to standard Go formatting practices and to resolve various test failures and linting issues.
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The
sendEachInBatchfunction, used for sending FCM messages individually within a batch, previously created a new goroutine for each message. This could lead to high CPU usage for large batches.This commit refactors
sendEachInBatchto use a fixed-size pool of concurrent operations (10 operations) to manage message sending. This limits the number of active goroutines, reducing CPU overhead and improving resource utilization.Key changes:
BatchResponse.Responsescorrectly matches the order of the input messages, even with concurrent processing.messaging_batch_test.goto comprehensively cover the new implementation, including scenarios for varying batch sizes, partial failures, early validation, and response ordering.