Hitless upgrade: Support initial implementation for synchronous Redis client - no handshake, no failing over notifications support. #3713
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vladvildanov
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Jul 29, 2025
vladvildanov
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Pull Request Overview
This PR implements hitless upgrade support for the synchronous Redis client by adding maintenance events handling. The implementation allows the Redis client to gracefully handle cluster rebalancing and node migration operations without losing connections or data.
Key changes:
- Added comprehensive maintenance events handling infrastructure for MOVING, MIGRATING, and MIGRATED events
- Implemented connection pool management for hitless upgrades during cluster maintenance
- Enhanced Redis client with maintenance events configuration and handlers
Reviewed Changes
Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| redis/maintenance_events.py | Core maintenance events classes and handlers for processing cluster rebalancing notifications |
| redis/connection.py | Enhanced connection and pool classes with maintenance state management and proactive reconnection support |
| redis/client.py | Updated Redis client to support maintenance events configuration and handle connection reconnection during maintenance |
| redis/_parsers/base.py | Extended parsers to handle maintenance-related push notifications (MOVING, MIGRATING, MIGRATED) |
| redis/_parsers/resp3.py | Updated RESP3 parser to properly handle push notifications during maintenance events |
| redis/_parsers/hiredis.py | Updated Hiredis parser to support maintenance event push notifications |
| tests/test_maintenance_events_handling.py | Comprehensive integration tests for maintenance events handling with mocked Redis protocol |
| tests/test_maintenance_events.py | Unit tests for maintenance event classes and handlers |
| tests/test_connection_pool.py | Minor test updates to support new connection pool functionality |
Comments suppressed due to low confidence (2)
redis/connection.py:385
- The parser is being set before protocol-specific configurations are applied. Line 407 shows that RESP3Parser is set when protocol is 3, but the initial parser setup happens before this check. This could lead to incorrect parser being used for maintenance events.
self.health_check_interval = health_check_interval
redis/connection.py:381
- This line appears to be indented incorrectly. The if statement at line 380 should control this block, but the indentation suggests it's not properly nested within the conditional block.
# Update the retry's supported errors with the specified errors
vladvildanov
requested changes
Aug 15, 2025
petyaslavova
changed the title
… tests for maintenance_events.py file
…tion pool - this should be a separate PR
… Refactored the maintenance events tests not to be multithreaded - we don't need it for those tests.
…ot processed in in Moving state. Tests are updated
…ply them during connect
…isting ones more generic
…e better retry_on_error handling on connection initialization.
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vladvildanov
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petyaslavova
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feat/hitless-upgrade-sync-standalone
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Description of change
Hitless upgrade support implementation for synchronous Redis client.