[SSHD-1294] Close MinaServiceFactory instances properly

Ensure that the IoProcessor pool is disposed, otherwise a selector may
not get closed, leading to a file handle leak.
diff --git a/CHANGES.md b/CHANGES.md
index 6cb456c..1f665c4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -22,6 +22,8 @@
 
 ## Bug fixes
 
+* [SSHD-1294](https://issues.apache.org/jira/browse/SSHD-1294) Close MinaServiceFactory instances properly
+
 ## Major code re-factoring
 
 ## Potential compatibility issues
diff --git a/sshd-mina/src/main/java/org/apache/sshd/mina/MinaServiceFactory.java b/sshd-mina/src/main/java/org/apache/sshd/mina/MinaServiceFactory.java
index 33fbb14..ab3ad28 100644
--- a/sshd-mina/src/main/java/org/apache/sshd/mina/MinaServiceFactory.java
+++ b/sshd-mina/src/main/java/org/apache/sshd/mina/MinaServiceFactory.java
@@ -54,4 +54,15 @@
     public IoAcceptor createAcceptor(IoHandler handler) {
         return autowireCreatedService(new MinaAcceptor(getFactoryManager(), handler, ioProcessor));
     }
+
+    @Override
+    protected void doCloseImmediately() {
+        try {
+            ioProcessor.dispose();
+        } catch (Exception e) {
+            log.debug("Exception caught while disposing IoProcessor pool", e);
+        } finally {
+            super.doCloseImmediately();
+        }
+    }
 }
diff --git a/sshd-mina/src/test/java/org/apache/sshd/mina/MinaSessionTest.java b/sshd-mina/src/test/java/org/apache/sshd/mina/MinaSessionTest.java
new file mode 100644
index 0000000..3de4497
--- /dev/null
+++ b/sshd-mina/src/test/java/org/apache/sshd/mina/MinaSessionTest.java
@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.sshd.mina;
+
+import java.lang.reflect.Field;
+
+import org.apache.mina.core.service.IoProcessor;
+import org.apache.sshd.client.SshClient;
+import org.apache.sshd.common.helpers.AbstractFactoryManager;
+import org.apache.sshd.common.io.IoServiceFactory;
+import org.apache.sshd.server.SshServer;
+import org.apache.sshd.util.test.BaseTestSupport;
+import org.junit.FixMethodOrder;
+import org.junit.Test;
+import org.junit.runners.MethodSorters;
+
+/**
+ * Tests specific to the MINA connection back-end.
+ *
+ * @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
+ */
+@FixMethodOrder(MethodSorters.NAME_ASCENDING)
+public class MinaSessionTest extends BaseTestSupport {
+
+    public MinaSessionTest() {
+        super();
+    }
+
+    private IoProcessor<?> getProcessor(AbstractFactoryManager manager) throws Exception {
+        IoServiceFactory ioServiceFactory = manager.getIoServiceFactory();
+        assertTrue("Unexpected type " + ioServiceFactory.getClass(), ioServiceFactory instanceof MinaServiceFactory);
+        // Get the ioProcessor field
+        Field f = MinaServiceFactory.class.getDeclaredField("ioProcessor");
+        f.setAccessible(true);
+        Object processor = f.get(ioServiceFactory);
+        assertTrue("Unexpected type " + processor.getClass(), processor instanceof IoProcessor<?>);
+        return (IoProcessor<?>) processor;
+    }
+
+    @Test
+    public void testIoProcessorClosed() throws Exception {
+        IoProcessor<?> ioProcessor = null;
+        try (SshServer server = setupTestServer()) {
+            server.start();
+            try (SshClient client = setupTestClient()) {
+                client.start();
+                ioProcessor = getProcessor(client);
+            }
+            assertTrue("MINA client IoProcessor should be closed", ioProcessor.isDisposed() || ioProcessor.isDisposing());
+            ioProcessor = getProcessor(server);
+        }
+        assertTrue("MINA server IoProcessor should be closed", ioProcessor.isDisposed() || ioProcessor.isDisposing());
+    }
+}