perf: throttle OG image generation — nice 19 + 50ms sleep between renders

bincio/serve/tasks.py

@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 import logging
+import os
 import shutil
 import subprocess
 import threading
@@ -102,6 +103,7 @@ def _site_rebuild_worker() -> None:
                          "--www-root", _webroot],
                         capture_output=True,
                         text=True,
+                        preexec_fn=lambda: os.nice(19),
                     )
                     if og.returncode != 0:
                         log.error("site-rebuild: og-images failed (rc=%d):\n%s\n%s",

scripts/generate_og_images.py

@@ -13,6 +13,7 @@ from __future__ import annotations
 import argparse
 import json
 import sys
+import time
 from pathlib import Path
 
 
@@ -58,6 +59,7 @@ def generate_all(data_dir: Path, www_root: Path) -> None:
                 out_path.write_bytes(png)
                 generated += 1
                 u_gen     += 1
+                time.sleep(0.05)
             except Exception as exc:
                 errors += 1
                 u_err  += 1