Druid在宕库重启后，无法创建新的连接

Question

我们的项目用的是druid 连接池，我们做宕库测试时，发现了重启后连接池没法创建新的连接，一直报如下错误：
Caused by: com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 60000, active 0, maxActive 20, creating 0, createErrorCount 287
at com.alibaba.druid.pool.DruidDataSource.getConnectionInternal(DruidDataSource.java:1599) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at com.alibaba.druid.pool.DruidDataSource.getConnectionDirect(DruidDataSource.java:1326) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:5007) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at com.alibaba.druid.filter.stat.StatFilter.dataSource_getConnection(StatFilter.java:680) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:5003) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1304) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1296) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:109) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:203) ~[rpc.register.server-1.4.0-SNAPSHOT.jar:?]
... 19 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.GeneratedConstructorAccessor26.newInstance(Unknown Source) ~[?:?]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_131]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[?:1.8.0_131]

看了网上说的是版本低，可是我升级到1.1.14版本也有这个问题，试了1.1.2版本也有这个问题，不是偶发，多次测试都会复现，项目的并发也不高。请问什么原因？

我们的连接池配置：
maxActive=20
initialSize=3
maxWait=60000
minIdle=3
validationQuery=SELECT 1
timeBetweenEvictionRunsMillis=60000
minEvictableIdleTimeMillis=300000
testWhileIdle=true
testOnBorrow=true
testOnReturn=false
poolPreparedStatements=true
maxOpenPreparedStatements=20

jstack 部分信息：
"Druid-ConnectionPool-Create-1984094095": awaiting notification on [0x000000078c826f50]
at sun.misc.Unsafe.park(Native Method)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2545)

使用数据库：mysql-5.5.54

目前感觉是druid 的CreateConnectionThread一直没有收到信号量，请帮忙看看是什么原因，非常感谢！

Answer 1

这个问题解决了吗，也碰到这个问题