c3p0池不能建立连接。如何调试这个？ [英] c3p0 pool cannot establish a coonection. How to debug this?

问题描述

我在服务器上安装了Tomcat和PostgreSQL。我有一个连接问题尝试从我的servlet连接到PostgreSQL数据库使用c3p0池。

I have a Tomcat and PostgreSQL installed on a server. I'm having a connection problem trying to connect from my servlet to PostgreSQL database using c3p0 pool.

如果我在我的笔记本电脑上本地运行Tomcat，我可以访问数据库。我也可以使用psql（即命令行sql实用程序）从服务器连接到数据库。但是当我试图部署我的servlet到服务器并建立连接时，我得到以下错误：

I can reach DB if I'm running Tomcat locally on my laptop. Also I can connect from server to DB using psql (i.e. command line sql utility). But when I'm trying to deploy my servlet to server and establish a connection I'm getting the following error:

java.sql.SQLException: Connections could not be acquired from the underlying database!
    com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
...
    com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
        com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
        com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
        com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)

找到问题？这应该是一个微不足道的问题，但可能是由于上午4点我缺少的东西:)提前感谢！

What should I check to locate a problem? It should be a trivial issue but may be due to 4 a.m. I'm missing something :) Thanks in advance!

PS：从所有网络接口连接允许数据库。 PostgreSQL JDBC驱动程序和c3p0池分布在WAR中。 Tomcat配置是非常默认的。不使用JNDI。

PS: Connection from all network interfaces are allowed to database. PostgreSQL JDBC driver and c3p0 pool are distributed in WAR. Tomcat configuration is very default. JNDI is not used.

推荐答案

您需要检查以下几项内容：

You need to check a few things:

1. java.policy其中tomcat使用
   （例如
   /etc/tomcat5.5/policy.d/02debian.policy）


2. db服务器设置（例如
   /etc/postgresql/pg_hba.conf）


3. 尝试在不使用池的情况下首先连接为
   在我的案例c3p0从我隐藏重要信息

这篇关于c3p0池不能建立连接。如何调试这个？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！