Merge pull request matplotlib#18667 from QuLogic/cache-lock

TST: Lock cache directory during cleanup.

Author: timhoffm

lib/matplotlib/testing/compare.py

@@ -34,10 +34,14 @@ def make_test_filename(fname, purpose):
     return '%s-%s%s' % (base, purpose, ext)
 
 
-def get_cache_dir():
+def _get_cache_path():
     cache_dir = Path(mpl.get_cachedir(), 'test_cache')
     cache_dir.mkdir(parents=True, exist_ok=True)
-    return str(cache_dir)
+    return cache_dir
+
+
+def get_cache_dir():
+    return str(_get_cache_path())
 
 
 def get_file_hash(path, block_size=2 ** 20):
@@ -286,7 +290,7 @@ def convert(filename, cache):
     # Only convert the file if the destination doesn't already exist or
     # is out of date.
     if not newpath.exists() or newpath.stat().st_mtime < path.stat().st_mtime:
-        cache_dir = Path(get_cache_dir()) if cache else None
+        cache_dir = _get_cache_path() if cache else None
 
         if cache_dir is not None:
             _register_conversion_cache_cleaner_once()
@@ -317,15 +321,17 @@ def _clean_conversion_cache():
     # (actually an overestimate: we don't convert png baselines and results).
     max_cache_size = 2 * baseline_images_size
     # Reduce cache until it fits.
-    cache_stat = {
-        path: path.stat() for path in Path(get_cache_dir()).glob("*")}
-    cache_size = sum(stat.st_size for stat in cache_stat.values())
-    paths_by_atime = sorted(  # Oldest at the end.
-        cache_stat, key=lambda path: cache_stat[path].st_atime, reverse=True)
-    while cache_size > max_cache_size:
-        path = paths_by_atime.pop()
-        cache_size -= cache_stat[path].st_size
-        path.unlink()
+    with cbook._lock_path(_get_cache_path()):
+        cache_stat = {
+            path: path.stat() for path in _get_cache_path().glob("*")}
+        cache_size = sum(stat.st_size for stat in cache_stat.values())
+        paths_by_atime = sorted(  # Oldest at the end.
+            cache_stat, key=lambda path: cache_stat[path].st_atime,
+            reverse=True)
+        while cache_size > max_cache_size:
+            path = paths_by_atime.pop()
+            cache_size -= cache_stat[path].st_size
+            path.unlink()
 
 
 @functools.lru_cache()  # Ensure this is only registered once.