Implements automatic cleanup of topic partitions with no active publishers
or subscribers to prevent memory accumulation from short-lived topics.
**Key Features:**
1. Activity Tracking (local_partition.go)
- Added lastActivityTime field to LocalPartition
- UpdateActivity() called on publish, subscribe, and message reads
- IsIdle() checks if partition has no publishers/subscribers
- GetIdleDuration() returns time since last activity
- ShouldCleanup() determines if partition eligible for cleanup
2. Cleanup Task (local_manager.go)
- Background goroutine runs every 1 minute (configurable)
- Removes partitions idle for > 5 minutes (configurable)
- Automatically removes empty topics after all partitions cleaned
- Proper shutdown handling with WaitForCleanupShutdown()
3. Broker Integration (broker_server.go)
- StartIdlePartitionCleanup() called on broker startup
- Default: check every 1 minute, cleanup after 5 minutes idle
- Transparent operation with sensible defaults
**Cleanup Process:**
- Checks: partition.Publishers.Size() == 0 && partition.Subscribers.Size() == 0
- Calls partition.Shutdown() to:
- Flush all data to disk (no data loss)
- Stop 3 goroutines (loopFlush, loopInterval, cleanupLoop)
- Free in-memory buffers (~100KB-10MB per partition)
- Close LogBuffer resources
- Removes partition from LocalTopic.Partitions
- Removes topic if no partitions remain
**Benefits:**
- Prevents memory bloat from short-lived topics
- Reduces goroutine count (3 per partition cleaned)
- Zero configuration required
- Data remains on disk, can be recreated on demand
- No impact on active partitions
**Example Logs:**
I Started idle partition cleanup task (check: 1m, timeout: 5m)
I Cleaning up idle partition topic-0 (idle for 5m12s, publishers=0, subscribers=0)
I Cleaned up 2 idle partition(s)
**Memory Freed per Partition:**
- In-memory message buffer: ~100KB-10MB
- Disk buffer cache
- 3 goroutines
- Publisher/subscriber tracking maps
- Condition variables and mutexes
**Related Issue:**
Prevents memory accumulation in systems with high topic churn or
many short-lived consumer groups, improving long-term stability
and resource efficiency.
**Testing:**
- Compiles cleanly
- No linting errors
- Ready for integration testing
fmt
chrislu
cd9b39ca50