On 2/8/20 10:20 PM, Glauber Costa wrote:
Perhaps you can reduce the
problem to a small C reproducer?
That was my intended next step, yes
s***, I didn't resist and I had to explain to my wife that no, I don't
like io_uring more than I like her.
But here it is.
This is a modification of test/connect.c.
I added a pthread comparison example that should achieve the same
sequence of events:
- try to sync connect
- wait a bit
- shutdown
I added a fixed wait for pthread to make sure that shutdown is not
called before connect.
For io_uring, the shutdown is configurable with the program argument.
This works just fine if I sleep before shutdown (as I would expect from a race).
This hangs every time if I don't.
Unless I am missing something I don't think this is the expected behavior
I think it is understandable. Since the socket is blocking uring moves
the work to a workqueue, and the shutdown() happens before the workqueue
has had a chance to process the connection attempt. So we'll have to
cancel the sqe.
Jens, does the blocking connect doesn't consume a kernel thread while
it's waiting for a connection? Or does it just set things up and move on?
