Pratik Mankawde 216d75e2e5 feat(nodestore): measure the NuDB write queue ...

NuDB serializes every insert behind one global mutex held for the whole
call, so a caller cannot see how long it waited. Record instead the
writer depth joined at and the wall time spent; with mean depth L and
mean insert time W, Little's Law gives service time W/L and queueing
W - W/L. That distinguishes a serialized write path from a saturated
disk: measured on a dev box the device sat 89 percent idle while
throughput stayed flat at 42k inserts per second.

The accounting runs from a ScopeExit guard because the insert can
allocate and therefore throw; leaking the depth would strand the gauge
above zero for the life of the process.

getWriteLoad also stops returning a hardcoded zero. It now reports
writer depth, which is bounded by the writing-thread count and so stays
far below the kMaxWriteLoadAcquire cutoff that gates history
acquisition, where returning bytes or microseconds would have silently
suppressed it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

2026-07-27 18:37:00 +01:00

..

xrpl

feat(nodestore): measure the NuDB write queue

2026-07-27 18:37:00 +01:00