On 2020-Sep-11, Fujii Masao wrote: > Ok, so my proposed patch degrated the performance in this case :( > This means that replacing spinlock with lwlock in pgss is not proper > approach for the lock contention issue on pgss... > > I proposed to split the spinlock for each pgss entry into two > to reduce the lock contention, upthread. One is for planner stats, > and the other is for executor stats. Is it worth working on > this approach as an alternative idea? Or does anyone have any better idea?
It does seem that the excl-locked section in pgss_store is rather large. (I admit I don't understand why would a LWLock decrease performance.) Andres suggested in [1] to use atomics for the counters together with a single lwlock to be used in shared mode only. I didn't quite understand what the lwlock is *for*, but maybe you do. [1] https://postgr.es/m/20200629231015.qlej5b3qpfe4u...@alap3.anarazel.de -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
