问题描述：
两个线程，一个线程加载加载Mysql驱动，一个加载Oracle驱动，然后被阻塞在Class.forName()
Main:
public class ClassThread {
public static void main(String[] args) {
InnerMysqlThread it1 = new InnerMysqlThread();
InnerOracleThread it2 = new InnerOracleThread();
it1.start();
it2.start();
}
}
加载Mysql:
public class InnerMysqlThread extends Thread {
@Override
public void run() {
try {
Class.forName("com.mysql.jdbc.Driver", true, this.getClass().getClassLoader());
System.out.println("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
加载Oracle：
public class InnerOracleThread extends Thread {
@Override
public void run() {
try {
Class.forName("oracle.jdbc.driver.OracleDriver", true, this.getClass().getClassLoader());
System.out.println("oracle.jdbc.driver.OracleDriver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
一直阻塞在java.sql.DriverManager中
线程dump为：
"Thread-1" prio=6 tid=0x00000000065bb800 nid=0xaa4 in Object.wait() [0x0000000006f4e000] java.lang.Thread.State: RUNNABLE at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at java.lang.Class.newInstance0(Class.java:357) at java.lang.Class.newInstance(Class.java:310) at sun.misc.Service$LazyIterator.next(Service.java:282) at java.sql.DriverService.run(DriverManager.java:664) at java.security.AccessController.doPrivileged(Native Method) at java.sql.DriverManager.loadInitialDrivers(DriverManager.java:506) at java.sql.DriverManager.initialize(DriverManager.java:612) at java.sql.DriverManager.registerDriver(DriverManager.java:281) - locked <0x000000077cf5cc38> (a java.lang.Class for java.sql.DriverManager) at oracle.jdbc.driver.OracleDriver.<clinit>(OracleDriver.java:188) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:249) at com.fable.hamal.node.core.classthreads.InnerOracleThread.run(InnerOracleThread.java:15) Locked ownable synchronizers: - None "Thread-0" prio=6 tid=0x00000000065ba800 nid=0x11c4 waiting for monitor entry [0x0000000006e4e000] java.lang.Thread.State: BLOCKED (on object monitor) at java.sql.DriverManager.registerDriver(DriverManager.java:280) - waiting to lock <0x000000077cf5cc38> (a java.lang.Class for java.sql.DriverManager) at com.mysql.jdbc.Driver.<clinit>(Driver.java:65) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:249) at com.fable.hamal.node.core.classthreads.InnerMysqlThread.run(InnerMysqlThread.java:15) Locked ownable synchronizers: - None
问题分析到线程：[Thread-0]被阻塞在lock <0x000000077cf5cc38>，而[Thread-1]持有lock <0x000000077cf5cc38>，但是却一直处在运行sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)方法中不结束，由于水平有限，不知道如何处理了。
