defaultMQProducer send order exception

在执行“SendResult sendResult = producer.send(mq, shardingKey);”时偶尔会抛出如下异常：
com.aliyun.openservices.ons.api.exception.ONSClientException: defaultMQProducer send order exception

    at com.aliyun.openservices.ons.api.impl.rocketmq.OrderProducerImpl.send(OrderProducerImpl.java:118) ~[ons-client-1.7.7.Final.jar:1.7.7.Final]       
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:318) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:304) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:276) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:263) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:318) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:304) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:266) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:318) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:304) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:846) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:131) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:511) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:112) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137) [netty-all-4.0.33.Final.jar:4.0.33.Final]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_65]