Get available execution threads

GET {scheme}://{host}:{port}/api/Schedule/GetNumberOfFreeThreads

Return available capacity for the current server. The default capacity is four; configuration can change it, and the result is clamped to zero. The calculation can clean up old execution entries. This is a snapshot, not a capacity reservation. Schedule-process concurrency, per-schedule page-renderer processes and data-driver row threads are different capacities. The number returned here does not describe all three and does not reserve capacity.