perf: cheap per-frame and per-fetch savings (#725)

Six small savings with no behaviour change: the odds fetch no longer pretty-prints every response for a debug line; the scroll integer-slice path drops a redundant full-frame np.ascontiguousarray; ledmatrix-web.service gets MALLOC_ARENA_MAX=2 like the display unit; core ESPN responses are parsed via response_json (orjson when installed); and the scroll frame stats go to INFO only for degraded windows plus a 5-minute heartbeat.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/base_odds_manager.py

@@ -20,6 +20,7 @@ from typing import Dict, Any, Optional, List, cast
 
 from src.common.api_helper import DEFAULT_HTTP_HEADERS
 from src.common.fetch_service import fetch_get, share_connection_pool
+from src.common.json_body import response_json
 
 
 
@@ -146,7 +147,7 @@ class BaseOddsManager:
             if _is_no_odds_marker(cached_data):
                 self.logger.debug("Cached no-odds marker for %s", cache_key)
                 return None
-            self.logger.debug(f"Using cached odds from ESPN for {cache_key}")
+            self.logger.debug("Using cached odds from ESPN for %s", cache_key)
             return cached_data
 
         if time.monotonic() < self._skip_network_until:
@@ -159,7 +160,7 @@ class BaseOddsManager:
                 self._skip_network_until - time.monotonic())
             return None
 
-        self.logger.debug(f"Cache miss - fetching fresh odds from ESPN for {cache_key}")
+        self.logger.debug("Cache miss - fetching fresh odds from ESPN for %s", cache_key)
 
         try:
             # Map league names to ESPN API format
@@ -173,26 +174,30 @@ class BaseOddsManager:
             
             espn_league = league_mapping.get(league, league)
             url = f"{self.base_url}/{sport}/leagues/{espn_league}/events/{event_id}/competitions/{event_id}/odds"
-            self.logger.debug(f"Requesting odds from URL: {url}")
+            self.logger.debug("Requesting odds from URL: %s", url)
             
             # The response cache may answer only inside this caller's own
             # interval, the age at which its cached odds expire anyway.
             response = fetch_get(self.session, url, timeout=self.request_timeout,
                                  cache_max_age=interval)
             response.raise_for_status()
-            raw_data = response.json()
+            raw_data = response_json(response)
 
             self._skip_network_until = 0.0   # reachable again
 
-            self.logger.debug(f"Received raw odds data from ESPN: {json.dumps(raw_data, indent=2)}")
+            # Guarded, not just %-style: the json.dumps argument would still be
+            # built for every response with DEBUG off.
+            if self.logger.isEnabledFor(logging.DEBUG):
+                self.logger.debug("Received raw odds data from ESPN: %s",
+                                  json.dumps(raw_data, indent=2))
             
             odds_data = self._extract_espn_data(raw_data)
             if odds_data:
-                self.logger.debug(f"Successfully extracted odds data: {odds_data}")
+                self.logger.debug("Successfully extracted odds data: %s", odds_data)
                 self.cache_manager.set(cache_key, odds_data, ttl=interval)
-                self.logger.debug(f"Saved odds data to cache for {cache_key} with TTL {interval}s")
+                self.logger.debug("Saved odds data to cache for %s with TTL %ss", cache_key, interval)
             else:
-                self.logger.debug(f"No odds data available for {cache_key}")
+                self.logger.debug("No odds data available for %s", cache_key)
                 # Cache the absence too, so the game is not re-requested
                 # on every update until the interval passes.
                 self.cache_manager.set(cache_key, {"no_odds": True}, ttl=interval)
@@ -226,12 +231,12 @@ class BaseOddsManager:
         Returns:
             Formatted odds data dictionary or None
         """
-        self.logger.debug(f"Extracting ESPN odds data. Data keys: {list(data.keys())}")
+        self.logger.debug("Extracting ESPN odds data. Data keys: %s", list(data.keys()))
         
         if "items" in data and data["items"]:
-            self.logger.debug(f"Found {len(data['items'])} items in odds data")
+            self.logger.debug("Found %d items in odds data", len(data['items']))
             item = data["items"][0]
-            self.logger.debug(f"First item keys: {list(item.keys())}")
+            self.logger.debug("First item keys: %s", list(item.keys()))
             
             # The ESPN API returns odds data directly in the item, not in a
             # providers array. ESPN sends explicit JSON nulls for absent
@@ -254,13 +259,17 @@ class BaseOddsManager:
                                     .get("pointSpread") or {}).get("value")
                 }
             }
-            self.logger.debug(f"Returning extracted odds data: {json.dumps(extracted_data, indent=2)}")
+            if self.logger.isEnabledFor(logging.DEBUG):
+                self.logger.debug("Returning extracted odds data: %s",
+                                  json.dumps(extracted_data, indent=2))
             return extracted_data
         
         # Check if this is a valid empty response or an unexpected structure
         if "count" in data and data["count"] == 0 and "items" in data and data["items"] == []:
             # This is a valid empty response - no odds available for this game
-            self.logger.debug(f"No odds available for this game. Response: {json.dumps(data, indent=2)}")
+            if self.logger.isEnabledFor(logging.DEBUG):
+                self.logger.debug("No odds available for this game. Response: %s",
+                                  json.dumps(data, indent=2))
             return None
         else:
             # This is an unexpected response structure

src/common/api_helper.py

@@ -17,6 +17,7 @@ from src.common.espn_dates import (
     store_espn_scoreboard_cache,
 )
 from src.common.fetch_service import fetch_get, fetch_post, share_connection_pool
+from src.common.json_body import response_json
 from typing import TYPE_CHECKING, Any, Dict, Mapping, Optional, cast
 
 import requests
@@ -157,7 +158,7 @@ class APIHelper:
             response.raise_for_status()
             
             # Parse JSON response
-            data: Dict[Any, Any] = response.json()
+            data: Dict[Any, Any] = response_json(response)
             
             # Cache response if cache key provided
             if cache_key and self.cache_manager:
@@ -304,7 +305,7 @@ class APIHelper:
             )
             response.raise_for_status()
             
-            return cast(Optional[Dict[Any, Any]], response.json())
+            return cast(Optional[Dict[Any, Any]], response_json(response))
             
         except requests.exceptions.RequestException as e:
             self.logger.error(f"POST request failed for {url}: {e}")

src/common/scroll_helper.py

@@ -28,6 +28,30 @@ import numpy as np
 # long over one frame, so a sample this large is an idle gap between scrolls.
 FPS_LOG_INTERVAL = 5.0
 
+# The stats line goes to INFO only when a window is worth an operator's
+# attention, as Vegas's FPS line does (src/vegas_mode/coordinator.py): every
+# 5s from every scroller was most of the journal on a healthy rig. A window is
+# degraded when its frame rate falls below this fraction of the rate it was
+# locked to (1 / its own median frame time; same 0.9 as Vegas) ...
+STATS_HEALTHY_FRACTION = 0.9
+# ... or when more than this share of its frames stalled (past 1.5x the
+# median). A 1% stall rate barely moves the mean, so the fps test alone would
+# miss the judder this line exists to show.
+STATS_DEGRADED_STALL_RATE = 0.01
+# A healthy scroller still logs at INFO this often, so silence in the journal
+# means stopped rather than fine. Every window is still logged at DEBUG.
+STATS_HEARTBEAT_INTERVAL = 300.0
+
+
+def frame_stats_degraded(stats: Dict[str, Any]) -> bool:
+    """Whether one frame_stats() window is worth logging at INFO."""
+    n = stats["frames"]
+    if n == 0 or stats["median"] <= 0:
+        return False
+    locked_fps = 1.0 / stats["median"]
+    return (stats["fps"] < locked_fps * STATS_HEALTHY_FRACTION
+            or stats["stalls"] > n * STATS_DEGRADED_STALL_RATE)
+
 
 def _rgb_pixels(item) -> np.ndarray:
     """An appended item's pixels as an RGB array, as pasting it would draw them."""
@@ -189,6 +213,11 @@ class ScrollHelper:
         # Every frame time since the last stats line, so the 5s summary can
         # report the tail rather than one arbitrary sample. Cleared on log.
         self._window: list = []
+        # INFO-level stats bookkeeping (see STATS_HEARTBEAT_INTERVAL). Kept
+        # across reset_scroll(): a heartbeat per scroll start would bring the
+        # chatter back. 0.0 so the first window after start-up is at INFO.
+        self._stats_last_info_log = 0.0
+        self._stats_was_degraded = False
         
         # Scrolling state management
         self.is_scrolling = False
@@ -573,9 +602,12 @@ class ScrollHelper:
         img_w = self.cached_array.shape[1]
 
         if end_x <= img_w:
-            # Normal case: single contiguous slice (fastest path)
-            frame_array = np.ascontiguousarray(self.cached_array[:, start_x:end_x])
-            return Image.frombytes('RGB', _size, frame_array.tobytes())
+            # Normal case: single contiguous slice (fastest path). tobytes()
+            # on the column-slice view already returns C-order bytes, so
+            # ascontiguousarray() first only added a second full-frame copy.
+            return Image.frombytes(
+                'RGB', _size,
+                self.cached_array[:, start_x:end_x].tobytes())
         else:
             # Ensure frame buffer is allocated for all non-simple paths
             if self._frame_buffer is None or self._frame_buffer.shape != (self.display_height, self.display_width, 3):
@@ -1207,10 +1239,23 @@ class ScrollHelper:
             # as an idle gap. There is nothing to report, and reporting the
             # gap itself is the bug above.
             if self._window:
-                self.logger.info(
-                    "Scroll frame stats - %s",
-                    format_frame_stats(self._window),
-                )
+                # INFO when degraded, on the window that recovers from it, and
+                # as a slow heartbeat; DEBUG otherwise.
+                degraded = frame_stats_degraded(frame_stats(self._window))
+                if (degraded or self._stats_was_degraded
+                        or current_time - self._stats_last_info_log
+                        >= STATS_HEARTBEAT_INTERVAL):
+                    self.logger.info(
+                        "Scroll frame stats - %s",
+                        format_frame_stats(self._window),
+                    )
+                    self._stats_last_info_log = current_time
+                elif self.logger.isEnabledFor(logging.DEBUG):
+                    self.logger.debug(
+                        "Scroll frame stats - %s",
+                        format_frame_stats(self._window),
+                    )
+                self._stats_was_degraded = degraded
             self.last_fps_log_time = current_time
             self.frame_count = 0
             self._window = []

src/dynamic_team_resolver.py

@@ -23,6 +23,7 @@ import requests
 from typing import Any, Dict, List
 
 from src.common.api_helper import DEFAULT_HTTP_HEADERS
+from src.common.json_body import response_json
 
 logger = logging.getLogger(__name__)
 
@@ -157,7 +158,7 @@ class DynamicTeamResolver:
             response = requests.get(rankings_url, headers=dict(DEFAULT_HTTP_HEADERS),
                                     timeout=self.request_timeout)
             response.raise_for_status()
-            data = response.json()
+            data = response_json(response)
             
             rankings = {}
             rankings_data = data.get('rankings', [])

src/logo_downloader.py

@@ -21,6 +21,7 @@ from PIL.PngImagePlugin import PngInfo
 from requests.adapters import HTTPAdapter
 from urllib3.util.retry import Retry
 from src.common.api_helper import DEFAULT_HTTP_HEADERS
+from src.common.json_body import response_json
 from src.common.logo_helper import MAX_LOGO_BYTES
 from src.common.permission_utils import (
     ensure_directory_permissions,
@@ -481,7 +482,7 @@ class LogoDownloader:
             logger.info(f"Fetching team data for {league} from ESPN API...")
             response = self.session.get(api_url, params={'limit':1000},headers=self.headers, timeout=self.request_timeout)
             response.raise_for_status()
-            data: Dict = response.json()
+            data: Dict = response_json(response)
             
             logger.info(f"Successfully fetched team data for {league}")
             return data
@@ -505,7 +506,7 @@ class LogoDownloader:
             logger.info(f"Fetching team data for team {team_id} in {league} from ESPN API...")
             response = self.session.get(f"{api_url}/{team_id}", headers=self.headers, timeout=self.request_timeout)
             response.raise_for_status()
-            data: Dict = response.json()
+            data: Dict = response_json(response)
             
             logger.info(f"Successfully fetched team data for {team_id} in {league}")
             return data