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@ljanyst @jlsalmon - what are your thoughts on a PR which removes the asynchronous capabilities from the python client?

I haven't found any way to actually use these safely.  Take the async example shipped with the code:
```
def callback( status, response, hostlist ):
  print "Called:", status, response, hostlist

with client.File() as f:
  status, response = f.open('root://localhost//tmp/eggs', OpenFlags.DELETE)
  status = f.fcntl( 'asdf', callback = callback )
  sleep(20)
```

This will deadlock if `fcntl` takes exactly 20 seconds:
1.  The main python thread will hold the GIL and close the XrdFile object, which takes an XrdCl mutex.
2.  The Xrootd asynchronous callback pool will take a XrdCl mutex and grab the GIL.

Hence, even this trivial example can lead to a deadlock!  (Of course, as I mentioned, *any* usage of the asynchronous callbacks can lead to a deadlock, so this is maybe not so surprising)

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Reply to this email directly or view it on GitHub:
https://github.com/xrootd/xrootd-python/issues/13#issuecomment-170358891

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