output: #fixed code
                               public ZooKeeper getClient(){
  		if (zooKeeper==null) {
  			try {
  				if (INSTANCE_INIT_LOCK.tryLock(2, TimeUnit.SECONDS)) {
  					if (zooKeeper==null) {		// 二次校验，防止并发创建client
  
  						// init new-client
  						ZooKeeper newZk = null;
  						try {
  							newZk = new ZooKeeper(zkaddress, 10000, watcher);
  							if (zkdigest!=null && zkdigest.trim().length()>0) {
  								newZk.addAuthInfo("digest",zkdigest.getBytes());		// like "account:password"
  							}
  							newZk.exists(zkpath, false);		// sync wait until succcess conn
  
  							// set success new-client
  							zooKeeper = newZk;
  							logger.info(">>>>>>>>>> xxl-rpc, XxlZkClient init success.");
  						} catch (Exception e) {
  							// close fail new-client
  							if (newZk != null) {
  								newZk.close();
  							}
  
  							logger.error(e.getMessage(), e);
  						} finally {
  							INSTANCE_INIT_LOCK.unlock();
  						}
  
  					}
  				}
  			} catch (InterruptedException e) {
  				logger.error(e.getMessage(), e);
  			}
  		}
  		if (zooKeeper == null) {
  			throw new XxlRpcException("XxlZkClient.zooKeeper is null.");
  		}
  		return zooKeeper;
  	}
input: #vulnerable code 
                               public ZooKeeper getClient(){
  		if (zooKeeper==null) {
  			try {
  				if (INSTANCE_INIT_LOCK.tryLock(2, TimeUnit.SECONDS)) {
  					if (zooKeeper==null) {		// 二次校验，防止并发创建client
  						try {
  							zooKeeper = new ZooKeeper(zkaddress, 10000, watcher);		// TODO，本地变量方式，成功才会赋值
  							if (zkdigest!=null && zkdigest.trim().length()>0) {
  								zooKeeper.addAuthInfo("digest",zkdigest.getBytes());		// like "account:password"
  							}
  
  							zooKeeper.exists(zkpath, false);	// sync
  						} catch (Exception e) {
  							logger.error(e.getMessage(), e);
  						} finally {
  							INSTANCE_INIT_LOCK.unlock();
  						}
  						logger.info(">>>>>>>>>> xxl-rpc, XxlZkClient init success.");
  					}
  				}
  			} catch (InterruptedException e) {
  				logger.error(e.getMessage(), e);
  			}
  		}
  		if (zooKeeper == null) {
  			throw new XxlRpcException("XxlZkClient.zooKeeper is null.");
  		}
  		return zooKeeper;
  	} 
                              #location 2 
                              #vulnerability type THREAD_SAFETY_VIOLATION