Limit internal metadata on multi-source files

CHANGELOG.md

@@ -7,6 +7,9 @@
 - Read some untiled tiffs using the tiff source ([#1512](../../pull/1512))
 - Speed up multi source compositing in tiled cases ([#1513](../../pull/1513))
 
+### Changes
+- Limit internal metadata on multi-source files with huge numbers of sources ([#1514](../../pull/1514))
+
 ## 1.28.1
 
 ### Improvements

sources/multi/large_image_source_multi/__init__.py

@@ -894,7 +894,7 @@ def getInternalMetadata(self, **kwargs):
         """
         Return additional known metadata about the tile source.  Data returned
         from this method is not guaranteed to be in any particular format or
-        have specific values.
+        have specific values.  Also, only the first 100 sources are used.
 
         :returns: a dictionary of data or None.
         """
@@ -903,7 +903,7 @@ def getInternalMetadata(self, **kwargs):
             'sources': copy.deepcopy(self._sources),
             'sourceFiles': [],
         }
-        for path in self._sourcePaths.values():
+        for path in self._sourcePaths.values()[:100]:
             source = self._sources[min(path['sourcenum'])]
             ts = self._openSource(source)
             result['sourceFiles'].append({