Eric Allam
eeab6bdeac
fix(run-engine): fix queue cache memory leak and replace MemoryStore with LRU cache (#2945)
- Fix memory leak in RunAttemptSystem queue cache - was keying by runId
instead of queue identifier
- Replace `@unkey/cache` MemoryStore with new LRUMemoryStore for O(1)
operations and better memory bounds
## Problem
### Cache Key Bug
The queue cache in `#resolveTaskRunExecutionQueue` was keyed by `runId`,
creating one cache entry per run instead of per queue. With 1-2 hour
TTLs and 5000 entry soft cap, these accumulated causing memory growth.
### MemoryStore Performance
The `@unkey/cache` MemoryStore uses O(n) synchronous iteration for
eviction, blocking the event loop at high throughput.
## Solution
### Cache Key Fix
Changed cache key from `params.runId` to queue identifier:
```typescript
const cacheKey = params.lockedQueueId ?? `${params.runtimeEnvironmentId}:${params.queueName}`;
```
LRU Cache
Created LRUMemoryStore adapter using lru-cache package:
- O(1) get/set/delete operations
- Strict memory bounds (hard max vs soft cap)
- No event loop blocking
Test Results:
| Metric | Before Fix | After Fix |
|---|---|---|
| Queue cache entries (per 1000 runs) | ~1000 | 1 |
| Old space growth | 32.27 MB | 5.45 MB |
| Heap growth | 7.21 MB (3.9%) | 4.81 MB (2.6%) |
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