On Nov 5, 2007, at 2:05 AM, Torsten Curdt wrote:
Is there anywhere documented the expected behavior of concurrent
changes in the filesystem? As an example:
Hdfs client C1 is slowly writing to "/path/a/file". Now another
hdfs client C2 renames "/path/a" to /path/b".
What happens? Will C1 continue to write but the file will be in "/
path/b" when it closes the file? Will C2 get an exception because
C1 is writing to "/path/a" so it cannot be renamed? And so on...
I will probably run off an do some test myself ...but is this
documented somewhere? I couldn't find it.
The short answer is that currently bad things happen. All of the hdfs
protocols call files by name and so changing the name of the file
while someone is writing to it will break the writer. In my opinion,
it would be better if dfs.ClientProtocol.create returned a lease
handle, which was used for the follow up addBlock, complete, and
renewLease.
-- Owen
