Java MySQL JDBC 内存泄漏 [英] Java MySQL JDBC Memory Leak

问题描述

好的，我的这个程序有很多(~300)个线程，每个线程都与一个中央数据库进行通信.我创建了一个到 DB 的全局连接，然后每个线程开始自己的业务，创建语句并执行它们.

Ok, so I have this program with many (~300) threads, each of which communicates with a central database. I create a global connection to the DB, and then each thread goes about its business creating statements and executing them.

在此过程中，我遇到了大量内存泄漏.分析堆转储后，我看到 com.mysql.jdbc.JDBC4Connection 对象为 70 MB，因为它在openStatements"(哈希映射)中有 800,000 个项目.某处它没有正确关闭我创建的语句，但我终生无法弄清楚在哪里(每次我打开一个，我也关闭它).知道为什么会发生这种情况吗?

Somewhere along the way, I have a massive memory leak. After analyzing the heap dump, I see that the com.mysql.jdbc.JDBC4Connection object is 70 MB, because it has 800,000 items in "openStatements" (a hash map). Somewhere it's not properly closing the statements that I create, but I cannot for the life of me figure out where (every single time I open one, I close it as well). Any ideas why this might be occurring?

推荐答案

你知道除非 MySQL 这么说，否则 JDBC 连接不是线程安全的.您不能跨线程共享它们，除非您使用连接池.此外，正如所指出的，您应该尝试/最终保证所有语句、结果集和连接都已关闭.

You know unless MySQL says so, JDBC Connections are NOT thread safe. You CANNOT share them across threads, unless you use a connection pool. In addition as pointed out you should be try/finally guaranteeing all statements, result sets, and connections are closed.

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