[jira] [Created] (PROTON-2930) Epoll proactor busy loop on socket error

["Clifford Jansen (Jira)" <ji...@apache.org>]

Clifford Jansen created PROTON-2930:
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             Summary: Epoll proactor busy loop on socket error
                 Key: PROTON-2930
                 URL: https://issues.apache.org/jira/browse/PROTON-2930
             Project: Qpid Proton
          Issue Type: Bug
          Components: proton-c
    Affects Versions: proton-c-0.40.0
         Environment: Linux
            Reporter: Clifford Jansen
            Assignee: Clifford Jansen


The epoll proactor code for AMQP connections notes EPOLLHUP and EPOLLERR conditions but defers reacting to the error until the next read or write on the socket.

It is possible for Linux sockets to note an EPOLLERR for a socket and leave EPOLLIN and EPOLLOUT unset.  At the same time, a send or recv on the socket will not provide a conclusive error condition, returning EAGAIN. The excellent reproducer program from PROTON-2928 will trigger this behaviour.  Eventually the kernel does signal one of EPOLLIN or EPOLLOUT providing the expected winding up of the connection, but the procator busy loops in the interim waiting for the change to the IO events.

It is possible there are other ways to trigger this beyond the known reproducer.

If the proactor knows the socket is no longer operational, it should not rearm the socket for polling as it does now.  Instead, it should determine the errno associated with the socket and force the closing of the connection's transport.



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