X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/353eb4f4c4fb52e7f2a1c9aaad93e9d6bf0088f4..0568c2d42703a7b839f2661968c05a23753f67c3:/sdk/python/arvados/arvfile.py

diff --git a/sdk/python/arvados/arvfile.py b/sdk/python/arvados/arvfile.py
index 9f43df15fa..9db19b05f6 100644
--- a/sdk/python/arvados/arvfile.py
+++ b/sdk/python/arvados/arvfile.py
@@ -38,6 +38,12 @@ def split(path):
         stream_name, file_name = '.', path
     return stream_name, file_name
 
+
+class UnownedBlockError(Exception):
+    """Raised when there's an writable block without an owner on the BlockManager."""
+    pass
+
+
 class _FileLikeObjectBase(object):
     def __init__(self, name, mode):
         self.name = name
@@ -571,7 +577,11 @@ class _BlockManager(object):
             # A WRITABLE block always has an owner.
             # A WRITABLE block with its owner.closed() implies that it's
             # size is <= KEEP_BLOCK_SIZE/2.
-            small_blocks = [b for b in self._bufferblocks.values() if b.state() == _BufferBlock.WRITABLE and b.owner.closed()]
+            try:
+                small_blocks = [b for b in self._bufferblocks.values() if b.state() == _BufferBlock.WRITABLE and b.owner.closed()]
+            except AttributeError:
+                # Writable blocks without owner shouldn't exist.
+                raise UnownedBlockError()
 
             if len(small_blocks) <= 1:
                 # Not enough small blocks for repacking