TL;DR
- 使用 114 DNS 时，反解析内网 IP 无响应，导致 SpringBoot 启动时 Liquibase 初始化阻塞约 30 秒
InetAddress.getLocalHost()获取到的可能是127.0.0.1，而非实际的内网 IP（如 192.168.x.x）
现象
SpringBoot启动时（HikariPool 初始化后）卡顿 30s
2025-11-09 15:14:33 INFO [main] com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Starting...
2025-11-09 15:14:33 INFO [main] com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection com.p6spy.engine.wrapper.ConnectionWrapper@7f6137fb
2025-11-09 15:14:33 INFO [main] com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Start completed.
排查
通过 jstack 分析线程栈，定位到 liquibase.util.NetUtil.getLocalHostName() 阻塞
# jps
jstack 66713
下方线程栈显示阻塞点位于
Inet6AddressImpl.getHostByAddr()
"main" #1 prio=5 os_prio=31 cpu=3549.34ms elapsed=14.86s tid=0x000000010a808200 nid=0xd03 runnable [0x000000016fa00000]java.lang.Thread.State: RUNNABLEat java.net.Inet6AddressImpl.getHostByAddr(java.base@17.0.14/Native Method)at java.net.InetAddress$PlatformNameService.getHostByAddr(java.base@17.0.14/InetAddress.java:940)at java.net.InetAddress.getHostFromNameService(java.base@17.0.14/InetAddress.java:662)at java.net.InetAddress.getHostName(java.base@17.0.14/InetAddress.java:605)at java.net.InetAddress.getHostName(java.base@17.0.14/InetAddress.java:577)at liquibase.util.NetUtil.getLocalHostName(NetUtil.java:79)at liquibase.sqlgenerator.core.LockDatabaseChangeLogGenerator.<clinit>(LockDatabaseChangeLogGenerator.java:30)
对应源码：
public class LockDatabaseChangeLogGenerator extends AbstractSqlGenerator<LockDatabaseChangeLogStatement> {@Overridepublic ValidationErrors validate(LockDatabaseChangeLogStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {return new ValidationErrors();}protected static final String hostname;protected static final String hostaddress;protected static final String hostDescription = (System.getProperty("liquibase.hostDescription") == null) ? "" :("#" + System.getProperty("liquibase.hostDescription"));static {try {// NetUtil.getLocalHostName() 导致阻塞hostname = NetUtil.getLocalHostName();hostaddress = NetUtil.getLocalHostAddress();} catch (Exception e) {throw new UnexpectedLiquibaseException(e);}}// ...
}
分析
NetUtil.getLocalHostName() 获取机器 IP：遍历网卡，调用 InetAddress.getHostName() 对内网 IP （192.168.10.2）做反解析，114 DNS（114.114.114.114）无响应，则导致阻塞 30s
package liquibase.util;// ...public class NetUtil {// .../*** @return Machine's host name. This method can be better to call than getting it off {@link #getLocalHost()} because sometimes the external address returned by that function does not have a useful hostname attached to it.* This function will make sure a good value is returned.*/public static String getLocalHostName() {if (hostName == null ) {try {// 遍历所有网络接口，找出 已启用 的 非点对点 网络接口，然后打印这些接口上每个非本地地址对应的主机名（hostname）InetAddress localHost = getLocalHost();if(localHost != null) {// 使用指定的 DNS 反解析获取的 IPhostName = localHost.getHostName();if (hostName.equals(localHost.getHostAddress())) {//sometimes the external IP interface doesn't have a hostname associated with it but localhost always doesInetAddress lHost = InetAddress.getLocalHost();if (lHost != null) {hostName = lHost.getHostName();}}}else {hostName = UNKNOWN_HOST_NAME;}} catch (Exception e) {Scope.getCurrentScope().getLog(NetUtil.class).fine("Error getting hostname", e);if (hostName == null) {hostName = UNKNOWN_HOST_NAME;}}}return hostName;}
}
大多数公共 DNS（如阿里、Google）在无法解析内网地址时返回 NXDOMAIN，而 114 DNS 无响应，导致 Java 原生反解析方法阻塞
# 耗时：0.228s
nslookup 192.168.10.2 223.5.5.5
Server: 223.5.5.5
Address: 223.5.5.5#53** server can't find 2.10.168.192.in-addr.arpa: NXDOMAIN
# 耗时：15.137s
nslookup 192.168.10.2 114.114.114.114
;; connection timed out; no servers could be reached
遍历网卡的原因
获取机器 IP 常用的方法：InetAddress.getLocalHost() 获取到的可能是127.0.0.1（与 JDK 实现有关），是一个本地回环地址（loopback address）。而非对外通信用的实际的网络 IP（例如 192.168.x.x 或 10.x.x.x）
为了获取 实际的网络 IP，一般使用类似上面 NetUtil.getLocalHostName() 的方式，遍历网卡获取实际 IP
参考：JDK-4665037 : InetAddress.getLocalHost() ambiguous on Linux systems
解决方案
最有效的解决方法是更换合适的 DNS。官方 issue 中有反馈类似的问题
参考：Slow NetUtil.getLocalHostName in Windows WSL2 #2440
参考资料
oepnjdk Inet6AddressImpl.c
liquibase NetUtil.java
)
