Arvados

class Handle(object):
    """Connects a numeric file handle to a File or Directory object that has
    been opened by the client.""" 

    def flush(self):
        if self.obj.writable():
            return self.obj.flush()

Several problems here.

1. Opendir and releasedir are only ever used to get the directory listing via readdir(). Because a directory handle isn't used to modify the directory, calling flush() is spurious.
2. If the Operations() object was created with enable_write=False, calling flush() is spurious.
3. The CollectionDirectory object is considered "writable" despite enable_write=False
4. Finally, computing committed() (to decide whether to actually send and updated manifest to the server) checks the _committed flag on every object. When there are 240000 files, that is expensive (especially because it makes a function call and increments/decrements a recursive mutex at each node.)

Todo:

1. Fix set_committed() to accept True or False and propagate the flag up or down accordingly. Change committed() to only test the local flag.
2. Don't flush directory handles at all.

Applied in changeset arvados|commit:9b2aa42213a7d333bbe93e040c2d152a70e9b5af.