Jeremy Daer
a5a5a62169
* Add GVL contention metrics via gvltools and Yabeda Expose per-request and process-wide GVL wait time as Prometheus metrics to diagnose suspected GVL contention from Solid Cable and Action Cable threads in Puma workers. Metrics: gvl_request_wait_seconds (histogram), gvl_waiting_threads (gauge), gvl_global_timer_total_seconds (gauge). * Add unit: :seconds to GVL histogram for consistency