Moving usage updates into the run engine to prevent inefficient &
additional incremental updates to the TaskRun table. Read/Modify/Write
pattern is safe inside of the run engine because of the run lock. We can
also now cap the usageDurationMs value from overflowing and causing an
error.
## Why?
This is preventing at least one update per TaskRun and instead updating
these values piggybacking on other updates.
## Aurora PostgreSQL Reader Consistency Notes
### TL;DR
Aurora readers share the same storage as the writer, but maintain
separate in-memory page caches. This means:
- **Storage is always consistent** - writes are synchronously committed
to shared storage
- **Page cache can lag** - typically <100ms, but can cause stale reads
if data is cached
### How It Works
1. Writer commits to shared storage (synchronous 4/6 quorum)
2. Writer sends cache invalidation messages to readers (asynchronous)
3. If reader has data in cache → returns cached (potentially stale)
value
4. If reader has cache miss → fetches from shared storage (always
current)
### Monitoring
```sql
SELECT server_id,
CASE WHEN session_id = 'MASTER_SESSION_ID' THEN 'Writer' ELSE 'Reader' END AS role,
replica_lag_in_msec
FROM aurora_replica_status();
```
Eric Allam
d893b26ed2