c3p0

C3P0是一个开源的JDBC连接池，它实现了数据源和JNDI绑定，支持JDBC3规范和JDBC2的标准扩展，设计非常简单易用 添加maven依赖 <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.44</version> </dependency> <dependency> <groupId>com.mchange</groupId> <artifactId>c3p0</artifactId> <version>0.9.5</version> </dependency> 编写C3P0工具类 public class C3P0Utils { private static ComboPooledDataSource dataSource = new ComboPooledDataSource("mysql"); public static DataSource getDataSource() { return dataSource; } public static Connection getConnection() { try { return dataSource.getConnection(); } catch (SQLException

二月 26, 2019 3:47:40 上午 org.apache.catalina.core.StandardWrapperValve invoke 严重: Servlet.service() for servlet [springmvc] in context with path [/rbac] threw exception [Handler dispatch failed; nested exception is java.lang.AbstractMethodError: Method com/mchange/v2/c3p0/impl/NewProxyPreparedStatement.isClosed()Z is abstract] with root cause java.lang.AbstractMethodError: Method com/mchange/v2/c3p0/impl/NewProxyPreparedStatement.isClosed()Z is abstract at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.isClosed(NewProxyPreparedStatement.java) at sun.reflect.NativeMethodAccessorImpl.invoke0

I have a model that has a pretty large graph of sub entities and hibernate ends up making around 9 statements to lazily fetch all of the data needed but about 4 levels deep I get a "could not initialize proxy - no Session" error and I am not sure why. Controller @Transactional(readOnly = true) @RequestMapping(value = "/v2/plans", method = RequestMethod.GET) public @ResponseBody List<PlanPresenter> show(HttpServletRequest request) throws Exception { List<PlanPresenter> planPresenters = new ArrayList<>(); CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder(); CriteriaQuery<Plan>

I am using WAS 7.1 along with c3p0 (v 0.9.2.1) & hibernate (3.2.6ga) After some hours of usage Websphere hangs and I see this message in the log [6/24/13 10:57:50:377 CEST] 00000031 ThreadMonitor W WSVR0605W: Thread "WebContainer : 24" (00000048) has been active for 759356 milliseconds and may be hung. There is/are 45 thread(s) in total in the server that may be hung. at java.lang.Object.wait(Native Method) at java.lang.Object.wait(Object.java:196) at com.mchange.v2.resourcepool.BasicResourcePool.awaitAcquire(BasicResourcePool.java:776) at com.mchange.v2.resourcepool.BasicResourcePool

I am working in a multisharded database environment in which downtime of a shard is not a fatal occurrence. When the application starts, all the shard info is loaded in a cache and respective Session objects loaded, however, it is expected that during the application uptime some of the shards may go down, in which case the application fails over to one of the remaining shards. It is almost a standard use case scenario. In some cases, I need to do a cross-shard scan and the way I do it is iterate through the map of sessions described above and retrieve data. The problem comes when I have a

定义： C3P0是一个开源的JDBC连接池，目前使用它的开源项目有 Hibernate，Spring 等。 数据库连接池的基本思想就是为数据库连接建立一个“缓冲池”。预先在缓冲池中放入一定数量的连接，当需要建立数据库连接时，只需从“缓冲池”中取出一个，使用完毕之后再放回去。我们可以通过设定连接池最大连接数来防止系统无尽的与数据库连接。获取一个连接，系统要在背后做很多消耗资源的事情，大多时候，创建连接的时间比执行sql语句的时间还要长。用户每次请求都需要向数据库获得链接，而数据库创建连接通常需要消耗相对较大的资源，创建时间也较长。 使用方法： 1.导入jar包：c3p0和mysql 2.配置xml文件 c3p0通过set方法进行配置 c3p0通过c3p0-config.xml文件进行配置 关于通过配置文件进行配置的话， 这边需要把xml文件方法同src文件夹下，c3p0会扫描文件进行相关的配置。 在Maven依赖中要加入c3p0和mysql-connector-java依赖，版本号一定要写。 废话不多说，下面是c3p0-config.xml文件的代码 是不是代码简洁了很多，所以在我们通常使用配置文件来创建数据库的连接池。 c3p0常用配置参数介绍 在前面的c3p0的相关配置中，我们看到了c3p0的配置参数，这里我们介绍几个常用的c3p0的配置参数 最基础的参数配置：

I have below exception javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException Internal Exception: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 70,400,002 milliseconds ago. The last packet sent successfully to the server was 70,400,003 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your

To specify SQLite connection properties there is org.sqlite.SQLiteConfig and it goes something like this: org.sqlite.SQLiteConfig config = new org.sqlite.SQLiteConfig(); config.setReadOnly(true); config.setPageSize(4096); //in bytes config.setCacheSize(2000); //number of pages config.setSynchronous(SQLiteConfig.SynchronousMode.OFF); config.setJournalMode(SQLiteConfig.JournalMode.OFF); SQLiteConnectionPoolDataSource dataSource = new SQLiteConnectionPoolDataSource(); Creating a connection pool with c3p0 goes something like this: ComboPooledDataSource cpds = new ComboPooledDataSource(); cpds