引起:org.postgresql.util.PSQLException:致命:为非复制超级用户连接保留剩余的连接槽

Question

我使用c3p0-0.9.5.2.jar和mchange-commons-java-0.2.11.jar来管理池连接,我使用postgreSql 9.3.

我在Prod环境中每天至少收到一次这些消息:

Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database!
    at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:118)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:692)
    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:140)
    at org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider.getConnection(LocalDataSourceConnectionProvider.java:81)
    at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
    ... 212 more
Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
    at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1469)
    at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:644)
    at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:554)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutAndMarkConnectionInUse(C3P0PooledConnectionPool.java:758)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:685)
    ... 215 more
Caused by: org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for non-replication superuser connections
    at org.postgresql.core.v3.ConnectionFactoryImpl.readStartupMessages(ConnectionFactoryImpl.java:712)

我在我的应用程序中有这个配置:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
         <bean id="dataSource" class = "com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
       <property name="driverClass" value="org.postgresql.Driver"/>

        <property name="jdbcUrl" value="jdbc:postgresql://localhost:5432/Test"/> 

        <property name="user" value="postgres"/>
        <property name="password" value="postgres"/>
           <!-- pool sizing -->
     <!-- pool sizing -->
        <property name="initialPoolSize" value="32" />
        <property name="minPoolSize" value="30" />
        <property name="maxPoolSize" value="300" />
        <property name="acquireIncrement" value="10" />
        <property name="maxStatements" value="0" />

        <!-- retries -->
        <property name="acquireRetryAttempts" value="30" />
        <property name="acquireRetryDelay" value="1000" /> <!-- 1s -->
        <property name="breakAfterAcquireFailure" value="false" />

        <!-- refreshing connections -->
        <property name="maxIdleTime" value="180" /> <!-- 3min -->
        <property name="maxConnectionAge" value="10" /> <!-- 1h -->

        <!-- timeouts and testing -->
        <property name="checkoutTimeout" value="0" /> <!-- 60s -->
        <property name="idleConnectionTestPeriod" value="60" /> <!-- 60 -->
        <property name="testConnectionOnCheckout" value="true" />
        <property name="preferredTestQuery" value="SELECT 1" />
        <property name="testConnectionOnCheckin" value="true" /> 

    </bean>
</beans>

在postgresql.conf中我有这个配置:

max_connections = 300
shared_buffers = 32GB

我的服务器有这样的性能:24 cpu,256 GB内存

使用该应用程序的用户数量约为1300

是否有人可以帮助我解决这个问题

先感谢您

Answer 1

存在superuser_reserved_connections为超级用户保留的连接插槽(默认为3个),以便即使在采用所有连接插槽的情况下也可以连接.

所以你实际上只有297个可用的插槽.

要么减少连接池的最大连接数,要么增加max_connectionsPostgreSQL.

顺便说一下,300太高了.您应该使用连接池的低得多的设置(除非数据库计算机中有数百个核心).

Answer 2

您看到的错误表明 postgres 没有更多可用连接。

在 SQL 数据库上运行此命令，看看您是否可以更好地了解哪些命令/用户占用了如此多的连接：

 select * from pg_stat_activity;

如果您只想知道打开连接的数量，请使用：

SELECT count(*) FROM pg_stat_activity;

有时打开的连接数达到 max_connections 限制。

对我来说，重新启动 pgAdmin 应用程序解决了这个问题。