[jira] [Created] (DIRMINA-1169) BindException on Java >= 11 due to race condition in AbstractPollingIoAcceptor

["Thomas Wolf (Jira)" <ji...@apache.org>]

Thomas Wolf created DIRMINA-1169:
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             Summary: BindException on Java >= 11 due to race condition in AbstractPollingIoAcceptor
                 Key: DIRMINA-1169
                 URL: https://issues.apache.org/jira/browse/DIRMINA-1169
             Project: MINA
          Issue Type: Bug
    Affects Versions: 2.2.1, 2.0.23, 2.1.6
            Reporter: Thomas Wolf


See also SSHD-1256.

The main acceptor loop does basically (somewhat simplified):
{code:java}
while (selectable) {
  registerHandles(); // Process registration queue: add new sockets (from bind()) to the selector with OP_ACCEPT, fulfills their open futures
  int selected = select();
  if (/* nothing to do */) {
    break; // and end the thread; higher layers will create a new one if needed
  }
  if (selected > 0) {
    processHandles(selectedHandles()); // Handle and hand off new connections
  }
  unregisterHandles(); // Process cancel queue: cancel SelectionKey, close ServerSocketChannel, fulfill the cancel future
}
{code}

With Java 11, unbinding a {{ServerSocketChannel}} changed:
 * [JDK-8214430|https://bugs.openjdk.org/browse/JDK-8214430]
 * [Java 11 Release Notes|https://www.oracle.com/java/technologies/javase/11-relnote-issues.html#JDK-8198562]

Essentially the unbind gives up the socket only at the next {{select()}} call. This causes two problems in Apache MINA's acceptor:
* The unbind future is set "done" before the socket is actually released.
* If a new binding for one of the unbound sockets is registered before that {{select()}} has been done, {{registerHandles()}} gets a {{BindException}} ("address already in use").

So for Java >= 11, the code must ensure that there is a {{select()}} between processing unbindings and processing new bindings, and the unbind futures must be set "done" only after that {{select()}}.



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