Enhance interactive 3D viz: overlays, server-side rendering, fast playback (#1310)

Author: sbryngelson

toolchain/mfc/viz/_step_cache.py

@@ -28,7 +28,7 @@
 
 logger = logging.getLogger(__name__)
 
-CACHE_MAX: int = 20
+CACHE_MAX: int = 40
 _cache: dict = {}
 _cache_order: list = []
 _in_flight: set = set()   # steps currently being prefetched
@@ -44,7 +44,7 @@ def _get_prefetch_pool() -> ThreadPoolExecutor:
     with _prefetch_pool_lock:
         if _prefetch_pool is None:
             _prefetch_pool = ThreadPoolExecutor(
-                max_workers=1, thread_name_prefix='mfc_prefetch')
+                max_workers=3, thread_name_prefix='mfc_prefetch')
             atexit.register(_prefetch_pool.shutdown, wait=False)
         return _prefetch_pool