Synchronized on `String#intern` is a bad practice, interning a string will make it a global object .Which means if you synchronized the same interned strings in different parts of your code , some shit'll happen ,eg : deadlock

https://github.com/alibaba/dubbo/blob/9cf27a36848c22fbfd00877449fbe0eaf53e040c/dubbo-rpc/dubbo-rpc-default/src/main/java/com/alibaba/dubbo/rpc/protocol/dubbo/DubboProtocol.java#L333
import com.alibaba.dubbo.common.utils.StringUtils;
import com.alibaba.dubbo.remoting.Channel;
import com.alibaba.dubbo.remoting.RemotingException;
import com.alibaba.dubbo.remoting.Transporter;
import com.alibaba.dubbo.remoting.exchange.ExchangeChannel;
import com.alibaba.dubbo.remoting.exchange.ExchangeClient;
import com.alibaba.dubbo.remoting.exchange.ExchangeHandler;
import com.alibaba.dubbo.remoting.exchange.ExchangeServer;
import com.alibaba.dubbo.remoting.exchange.Exchangers;
import com.alibaba.dubbo.remoting.exchange.support.ExchangeHandlerAdapter;
import com.alibaba.dubbo.rpc.Exporter;
import com.alibaba.dubbo.rpc.Invocation;
import com.alibaba.dubbo.rpc.Invoker;
import com.alibaba.dubbo.rpc.Protocol;
import com.alibaba.dubbo.rpc.RpcContext;
import com.alibaba.dubbo.rpc.RpcException;
import com.alibaba.dubbo.rpc.RpcInvocation;
import com.alibaba.dubbo.rpc.protocol.AbstractProtocol;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
/**
 * dubbo protocol support.
 */
public class DubboProtocol extends AbstractProtocol {