druid 获取数据库连接失败，一直wait.DruidDataSource.takeLast

at sun.misc.Unsafe.park(Native Method)

• parking to wait for <0x0000000780199268> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
  at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
  at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
  at com.alibaba.druid.pool.DruidDataSource.takeLast(DruidDataSource.java:1448)
  at com.alibaba.druid.pool.DruidDataSource.getConnectionInternal(DruidDataSource.java:1090)

问题：

高并发场景，Druid获取数据库连接一直等待，获取不了数据库链接;

解决办法：

• 先确保 spring.datasource.maxWait 不为 -1, -1表示永久等待， 可以配置为6000， 参考配置

• 没有采用druid starter的情况下， 可以试下在代码中手动配置 DataSource； 实测有效

@Slf4j
@Configuration
public class DruidConfig {
    @Value("${spring.datasource.url}")
    private String dbUrl;
    @Value("${spring.datasource.username}")
    private String username;
    @Value("${spring.datasource.password}")
    private String password;
    @Value("${spring.datasource.druid.username:admin}")
    private String druidUsername;
    @Value("${spring.datasource.druid.password:hd123}")
    private String druidPassword;
    @Value("${spring.datasource.driver-class-name:com.mysql.jdbc.Driver}")
    private String driverClassName;
    @Value("${spring.datasource.initialSize:10}")
    private int initialSize;
    @Value("${spring.datasource.minIdle:10}")
    private int minIdle;
    @Value("${spring.datasource.maxActive:1000}")
    private int maxActive;
    @Value("${spring.datasource.maxWait:-1}")
    private int maxWait;
    @Value("${spring.datasource.timeBetweenEvictionRunsMillis:60000}")
    private int timeBetweenEvictionRunsMillis;
    @Value("${spring.datasource.minEvictableIdleTimeMillis:1800000}")
    private int minEvictableIdleTimeMillis;
    @Value("${spring.datasource.validationQuery:SELECT 1}")
    private String validationQuery;
    @Value("${spring.datasource.testWhileIdle:true}")
    private boolean testWhileIdle;
    @Value("${spring.datasource.testOnBorrow:false}")
    private boolean testOnBorrow;
    @Value("${spring.datasource.testOnReturn:false}")
    private boolean testOnReturn;
    @Value("${spring.datasource.poolPreparedStatements:true}")
    private boolean poolPreparedStatements;
    @Value("${spring.datasource.filters:stat,log4j}")
    private String filters;
    @Value("${spring.datasource.logSlowSql:true}")
    private String logSlowSql;

    public DruidConfig() {
    }

    @Bean
    public ServletRegistrationBean druidServlet() {
        ServletRegistrationBean reg = new ServletRegistrationBean();
        reg.setServlet(new StatViewServlet());
        reg.addUrlMappings(new String[]{"/druid/*"});
        reg.addInitParameter("loginUsername", this.druidUsername);
        reg.addInitParameter("loginPassword", this.druidPassword);
        reg.addInitParameter("logSlowSql", this.logSlowSql);
        return reg;
    }

    @Bean
    @Primary
    public DataSource druidDataSource() {
        DruidDataSource datasource = new DruidDataSource();
        datasource.setUrl(this.dbUrl);
        datasource.setUsername(this.username);
        datasource.setPassword(this.password);
        datasource.setDriverClassName(this.driverClassName);
        datasource.setInitialSize(this.initialSize);
        datasource.setMinIdle(this.minIdle);
        datasource.setMaxActive(this.maxActive);
        datasource.setMaxWait(this.maxWait);
        datasource.setTimeBetweenEvictionRunsMillis(this.timeBetweenEvictionRunsMillis);
        datasource.setMinEvictableIdleTimeMillis(this.minEvictableIdleTimeMillis);
        datasource.setValidationQuery(this.validationQuery);
        datasource.setTestWhileIdle(this.testWhileIdle);
        datasource.setTestOnBorrow(this.testOnBorrow);
        datasource.setTestOnReturn(this.testOnReturn);
        datasource.setPoolPreparedStatements(this.poolPreparedStatements);
        datasource.setConnectionInitSqls(Collections.singletonList("set names utf8mb4"));

        try {
            datasource.setFilters(this.filters);
        } catch (SQLException var3) {
            log.error("druid configuration initialization filter", var3);
        }

        return datasource;
    }
}