diff --git a/src/main/java/com/alibaba/druid/util/TransferQueue.java b/src/main/java/com/alibaba/druid/util/TransferQueue.java
deleted file mode 100644
index f6a7df121a..0000000000
--- a/src/main/java/com/alibaba/druid/util/TransferQueue.java
+++ /dev/null
@@ -1,146 +0,0 @@
-/*
- * Copyright 1999-2011 Alibaba Group Holding Ltd.
- *
- * Licensed 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 com.alibaba.druid.util;
-
-import java.util.concurrent.BlockingQueue;
-import java.util.concurrent.SynchronousQueue;
-import java.util.concurrent.TimeUnit;
-
-
-/**
- * A {@link BlockingQueue} in which producers may wait for consumers
- * to receive elements.  A {@code TransferQueue} may be useful for
- * example in message passing applications in which producers
- * sometimes (using method {@link #transfer}) await receipt of
- * elements by consumers invoking {@code take} or {@code poll}, while
- * at other times enqueue elements (via method {@code put}) without
- * waiting for receipt.
- * {@linkplain #tryTransfer(Object) Non-blocking} and
- * {@linkplain #tryTransfer(Object,long,TimeUnit) time-out} versions of
- * {@code tryTransfer} are also available.
- * A {@code TransferQueue} may also be queried, via {@link
- * #hasWaitingConsumer}, whether there are any threads waiting for
- * items, which is a converse analogy to a {@code peek} operation.
- *
- * <p>Like other blocking queues, a {@code TransferQueue} may be
- * capacity bounded.  If so, an attempted transfer operation may
- * initially block waiting for available space, and/or subsequently
- * block waiting for reception by a consumer.  Note that in a queue
- * with zero capacity, such as {@link SynchronousQueue}, {@code put}
- * and {@code transfer} are effectively synonymous.
- *
- * <p>This interface is a member of the
- * <a href="{@docRoot}/../technotes/guides/collections/index.html">
- * Java Collections Framework</a>.
- *
- * @since 1.7
- * @author Doug Lea
- * @param <E> the type of elements held in this collection
- */
-public interface TransferQueue<E> extends BlockingQueue<E> {
-    /**
-     * Transfers the element to a waiting consumer immediately, if possible.
-     *
-     * <p>More precisely, transfers the specified element immediately
-     * if there exists a consumer already waiting to receive it (in
-     * {@link #take} or timed {@link #poll(long,TimeUnit) poll}),
-     * otherwise returning {@code false} without enqueuing the element.
-     *
-     * @param e the element to transfer
-     * @return {@code true} if the element was transferred, else
-     *         {@code false}
-     * @throws ClassCastException if the class of the specified element
-     *         prevents it from being added to this queue
-     * @throws NullPointerException if the specified element is null
-     * @throws IllegalArgumentException if some property of the specified
-     *         element prevents it from being added to this queue
-     */
-    boolean tryTransfer(E e);
-
-    /**
-     * Transfers the element to a consumer, waiting if necessary to do so.
-     *
-     * <p>More precisely, transfers the specified element immediately
-     * if there exists a consumer already waiting to receive it (in
-     * {@link #take} or timed {@link #poll(long,TimeUnit) poll}),
-     * else waits until the element is received by a consumer.
-     *
-     * @param e the element to transfer
-     * @throws InterruptedException if interrupted while waiting,
-     *         in which case the element is not left enqueued
-     * @throws ClassCastException if the class of the specified element
-     *         prevents it from being added to this queue
-     * @throws NullPointerException if the specified element is null
-     * @throws IllegalArgumentException if some property of the specified
-     *         element prevents it from being added to this queue
-     */
-    void transfer(E e) throws InterruptedException;
-
-    /**
-     * Transfers the element to a consumer if it is possible to do so
-     * before the timeout elapses.
-     *
-     * <p>More precisely, transfers the specified element immediately
-     * if there exists a consumer already waiting to receive it (in
-     * {@link #take} or timed {@link #poll(long,TimeUnit) poll}),
-     * else waits until the element is received by a consumer,
-     * returning {@code false} if the specified wait time elapses
-     * before the element can be transferred.
-     *
-     * @param e the element to transfer
-     * @param timeout how long to wait before giving up, in units of
-     *        {@code unit}
-     * @param unit a {@code TimeUnit} determining how to interpret the
-     *        {@code timeout} parameter
-     * @return {@code true} if successful, or {@code false} if
-     *         the specified waiting time elapses before completion,
-     *         in which case the element is not left enqueued
-     * @throws InterruptedException if interrupted while waiting,
-     *         in which case the element is not left enqueued
-     * @throws ClassCastException if the class of the specified element
-     *         prevents it from being added to this queue
-     * @throws NullPointerException if the specified element is null
-     * @throws IllegalArgumentException if some property of the specified
-     *         element prevents it from being added to this queue
-     */
-    boolean tryTransfer(E e, long timeout, TimeUnit unit)
-        throws InterruptedException;
-
-    /**
-     * Returns {@code true} if there is at least one consumer waiting
-     * to receive an element via {@link #take} or
-     * timed {@link #poll(long,TimeUnit) poll}.
-     * The return value represents a momentary state of affairs.
-     *
-     * @return {@code true} if there is at least one waiting consumer
-     */
-    boolean hasWaitingConsumer();
-
-    /**
-     * Returns an estimate of the number of consumers waiting to
-     * receive elements via {@link #take} or timed
-     * {@link #poll(long,TimeUnit) poll}.  The return value is an
-     * approximation of a momentary state of affairs, that may be
-     * inaccurate if consumers have completed or given up waiting.
-     * The value may be useful for monitoring and heuristics, but
-     * not for synchronization control.  Implementations of this
-     * method are likely to be noticeably slower than those for
-     * {@link #hasWaitingConsumer}.
-     *
-     * @return the number of consumers waiting to receive elements
-     */
-    int getWaitingConsumerCount();
-}