Intermittent connection pool exhaustion: idle connection drop vs request queuing in xd

Determine whether xd’s Connection Pool Management silently discards idle connections or queues incoming requests when a transient spike drives the pool past its configured maximum size.

The documentation describes auto‑expansion up to a limit or a fail‑fast mode, but it does not clarify the fate of idle connections during brief overloads, nor whether leak‑detection overhead influences this decision. Clarifying this behavior is essential for tuning timeout, validation, and leak‑detection settings under variable load.

Does xd drop idle connections to free pool capacity during a short spike, or does it hold requests until a connection becomes available?
If idle connections are dropped, what criteria (e.g., idle time, validation failure) trigger the eviction?
Does enabling leak detection alter the choice between dropping and queuing?