线程在 javaagent 阻塞退出中启动
thread started in javaagent blocking exit
在我的 javagent 中，我启动了一个 HttpServer：
public static void premain(String agentArgs, Instrumentation inst) throws InstantiationException, IOException {
HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
server.createContext("/report", new ReportHandler());
server.createContext("/data", new DataHandler());
server.createContext("/stack", new StackHandler());
ExecutorService es = Executors.newCachedThreadPool(new ThreadFactory() {
int count = 0;
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setName("JDBCLD-HTTP-SERVER" + count++);
return t;
}
});
server.setExecutor(es);
server.start();
// how to properly close ?
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
server.stop(5);
log.info("internal httpserver has been closed.");
es.shutdown();
try {
if (!es.awaitTermination(60, TimeUnit.SECONDS)) {
log.warn("executor service of internal httpserver not closing in 60 seconds");
es.shutdownNow();
if (!es.awaitTermination(60, TimeUnit.SECONDS))
log.error("executor service of internal httpserver not closing in 120 seconds, give up");
}else {
log.info("executor service of internal httpserver closed.");
}
} catch (InterruptedException ie) {
log.warn("thread interrupted, shutdown executor service of internal httpserver");
es.shutdownNow();
Thread.currentThread().interrupt();
}
}
});
// other instrumention code ignored ...
}
测试程序：
public class AgentTest {
public static void main(String[] args) throws SQLException {
HikariConfig config = new HikariConfig();
config.setJdbcUrl("jdbc:oracle:thin:@172.31.27.182:1521/pas");
config.setUsername("pas");
config.setPassword("pas");
HikariDataSource ds = new HikariDataSource(config);
Connection c = ds.getConnection();
Connection c1 = ds.getConnection();
c.getMetaData();
try {
Thread.sleep(1000 * 60 * 10);
} catch (InterruptedException e) {
e.printStackTrace();
c.close();
c1.close();
ds.close();
}
c.close();
c1.close();
ds.close();
}
}
当目标 jvm 退出时，我想要停止 HttpServer。但是当我的测试 java 程序完成时，主线程停止但整个 jvm 进程不会终止，上面代码中的关闭钩子不会执行。如果我在 eclipse IDE 中单击 'terminate' 按钮，eclipse 将显示错误：
但至少 jvm 会退出，并且我的关闭钩子会被调用。
根据 java.lang.Runtime 的 java 文档：
The Java virtual machine shuts down in response to two kinds of
events:
The program exits normally, when the last non-daemon thread exits or
when the exit (equivalently, System.exit) method is invoked, or The
virtual machine is terminated in response to a user interrupt, such as
typing ^C, or a system-wide event, such as user logoff or system
shutdown.
com.sun.net.httpserver.HttpServer 将启动一个非守护程序调度程序线程，该线程将在 HttpServer#stop 被调用时退出，所以我面临死锁。
non-daemon thread not finish -> shutdown hook not triggered -> can't
stop server -> non-daemon thread not finish
有什么好主意吗？请注意我无法修改定位应用程序的代码。
应用 kriegaex 的答案后更新
I added some logging to watch dog thread, and here is outputs:
2021-09-22 17:30:00.967 INFO - Connnection@1594791957 acquired by 40A4F128987F8BD9C0EE6749895D1237
2021-09-22 17:30:00.968 DEBUG - Stack@40A4F128987F8BD9C0EE6749895D1237:
java.lang.Throwable:
at com.zaxxer.hikari.pool.ProxyConnection.<init>(ProxyConnection.java:102)
at com.zaxxer.hikari.pool.HikariProxyConnection.<init>(HikariProxyConnection.java)
at com.zaxxer.hikari.pool.ProxyFactory.getProxyConnection(ProxyFactory.java)
at com.zaxxer.hikari.pool.PoolEntry.createProxyConnection(PoolEntry.java:97)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:192)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:162)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:100)
at agenttest.AgentTest.main(AgentTest.java:19)
2021-09-22 17:30:00.969 INFO - Connnection@686560878 acquired by 464555C270688B747CA211DE489B7730
2021-09-22 17:30:00.969 DEBUG - Stack@464555C270688B747CA211DE489B7730:
java.lang.Throwable:
at com.zaxxer.hikari.pool.ProxyConnection.<init>(ProxyConnection.java:102)
at com.zaxxer.hikari.pool.HikariProxyConnection.<init>(HikariProxyConnection.java)
at com.zaxxer.hikari.pool.ProxyFactory.getProxyConnection(ProxyFactory.java)
at com.zaxxer.hikari.pool.PoolEntry.createProxyConnection(PoolEntry.java:97)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:192)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:162)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:100)
at agenttest.AgentTest.main(AgentTest.java:20)
2021-09-22 17:30:00.971 DEBUG - Connnection@1594791957 used by getMetaData
2021-09-22 17:30:01.956 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:01.956 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:02.956 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:02.956 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:03.957 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:03.957 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:04.959 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:04.959 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:05.959 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:05.960 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:06.960 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:06.960 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:07.961 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:07.961 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:08.961 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:08.961 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:09.962 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:09.962 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:10.962 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:10.963 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:10.976 INFO - Connnection@1594791957 released
2021-09-22 17:30:10.976 DEBUG - set connection count to 0 by stack hash 40A4F128987F8BD9C0EE6749895D1237
2021-09-22 17:30:10.976 INFO - Connnection@686560878 released
2021-09-22 17:30:10.976 DEBUG - set connection count to 0 by stack hash 464555C270688B747CA211DE489B7730
2021-09-22 17:30:11.963 DEBUG - there is still 10 active threads, keep wathcing
2021-09-22 17:30:11.963 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true DestroyJavaVM#false
2021-09-22 17:30:12.964 DEBUG - there is still 10 active threads, keep wathcing
更新
我想支持所有类型的 java 应用程序，包括 Web 应用程序 运行 servlet 容器和单独的标准 javase 应用程序。
这里有一点 MCVE 说明 ewrammer 的想法。我使用 byte-buddy-agent 小助手库来动态附加代理，以便使我的示例自包含，从 main 方法直接启动 Java 代理。我省略了 运行 这个例子所必需的 3 个简单的空操作虚拟处理程序 类。
package org.acme.agent;
import com.sun.net.httpserver.HttpServer;
import net.bytebuddy.agent.ByteBuddyAgent;
import java.io.IOException;
import java.lang.instrument.Instrumentation;
import java.net.InetSocketAddress;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
public class Agent {
public static void premain(String agentArgs, Instrumentation inst) throws IOException {
HttpServer httpServer = HttpServer.create(new InetSocketAddress(8000), 0);
ExecutorService executorService = getExecutorService(httpServer);
Runtime.getRuntime().addShutdownHook(getShutdownHook(httpServer, executorService));
// other instrumention code ignored ...
startWatchDog();
}
private static ExecutorService getExecutorService(HttpServer server) {
server.createContext("/report", new ReportHandler());
server.createContext("/data", new DataHandler());
server.createContext("/stack", new StackHandler());
ExecutorService executorService = Executors.newCachedThreadPool(new ThreadFactory() {
int count = 0;
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setName("JDBCLD-HTTP-SERVER" + count++);
return t;
}
});
server.setExecutor(executorService);
server.start();
return executorService;
}
private static Thread getShutdownHook(HttpServer httpServer, ExecutorService executorService) {
return new Thread(() -> {
httpServer.stop(5);
System.out.println("Internal HTTP server has been stopped");
executorService.shutdown();
try {
if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
System.out.println("Executor service of internal HTTP server not closing in 60 seconds");
executorService.shutdownNow();
if (!executorService.awaitTermination(60, TimeUnit.SECONDS))
System.out.println("Executor service of internal HTTP server not closing in 120 seconds, giving up");
}
else {
System.out.println("Executor service of internal HTTP server closed");
}
}
catch (InterruptedException ie) {
System.out.println("Thread interrupted, shutting down executor service of internal HTTP server");
executorService.shutdownNow();
Thread.currentThread().interrupt();
}
});
}
private static void startWatchDog() {
ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
while (threadGroup.getParent() != null)
threadGroup = threadGroup.getParent();
final ThreadGroup topLevelThreadGroup = threadGroup;
// Plus 1, because of the monitoring thread we are going to start right below
final int activeCount = topLevelThreadGroup.activeCount() + 1;
new Thread(() -> {
do {
try {
Thread.sleep(1000);
}
catch (InterruptedException ignored) {}
} while (topLevelThreadGroup.activeCount() > activeCount);
System.exit(0);
}).start();
}
public static void main(String[] args) throws IOException {
premain(null, ByteBuddyAgent.install());
Random random = new Random();
for (int i = 0; i < 5; i++) {
new Thread(() -> {
int threadDurationSeconds = 1 + random.nextInt(10);
System.out.println("Starting thread with duration " + threadDurationSeconds + " s");
try {
Thread.sleep(threadDurationSeconds * 1000);
System.out.println("Finishing thread after " + threadDurationSeconds + " s");
}
catch (InterruptedException ignored) {}
}).start();
}
}
}
如您所见，这基本上是您的示例代码，重构为几个辅助方法以提高可读性，以及新的看门狗方法。非常简单。
这会生成如下控制台日志：
Starting thread with duration 6 s
Starting thread with duration 6 s
Starting thread with duration 8 s
Starting thread with duration 7 s
Starting thread with duration 5 s
Finishing thread after 5 s
Finishing thread after 6 s
Finishing thread after 6 s
Finishing thread after 7 s
Finishing thread after 8 s
internal httpserver has been closed.
executor service of internal httpserver closed.
在我的 javagent 中，我启动了一个 HttpServer：
public static void premain(String agentArgs, Instrumentation inst) throws InstantiationException, IOException {
HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
server.createContext("/report", new ReportHandler());
server.createContext("/data", new DataHandler());
server.createContext("/stack", new StackHandler());
ExecutorService es = Executors.newCachedThreadPool(new ThreadFactory() {
int count = 0;
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setName("JDBCLD-HTTP-SERVER" + count++);
return t;
}
});
server.setExecutor(es);
server.start();
// how to properly close ?
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
server.stop(5);
log.info("internal httpserver has been closed.");
es.shutdown();
try {
if (!es.awaitTermination(60, TimeUnit.SECONDS)) {
log.warn("executor service of internal httpserver not closing in 60 seconds");
es.shutdownNow();
if (!es.awaitTermination(60, TimeUnit.SECONDS))
log.error("executor service of internal httpserver not closing in 120 seconds, give up");
}else {
log.info("executor service of internal httpserver closed.");
}
} catch (InterruptedException ie) {
log.warn("thread interrupted, shutdown executor service of internal httpserver");
es.shutdownNow();
Thread.currentThread().interrupt();
}
}
});
// other instrumention code ignored ...
}
测试程序：
public class AgentTest {
public static void main(String[] args) throws SQLException {
HikariConfig config = new HikariConfig();
config.setJdbcUrl("jdbc:oracle:thin:@172.31.27.182:1521/pas");
config.setUsername("pas");
config.setPassword("pas");
HikariDataSource ds = new HikariDataSource(config);
Connection c = ds.getConnection();
Connection c1 = ds.getConnection();
c.getMetaData();
try {
Thread.sleep(1000 * 60 * 10);
} catch (InterruptedException e) {
e.printStackTrace();
c.close();
c1.close();
ds.close();
}
c.close();
c1.close();
ds.close();
}
}
当目标 jvm 退出时，我想要停止 HttpServer。但是当我的测试 java 程序完成时，主线程停止但整个 jvm 进程不会终止，上面代码中的关闭钩子不会执行。如果我在 eclipse IDE 中单击 'terminate' 按钮，eclipse 将显示错误：
根据 java.lang.Runtime 的 java 文档：
The Java virtual machine shuts down in response to two kinds of events:
The program exits normally, when the last non-daemon thread exits or when the exit (equivalently, System.exit) method is invoked, or The virtual machine is terminated in response to a user interrupt, such as typing ^C, or a system-wide event, such as user logoff or system shutdown.
com.sun.net.httpserver.HttpServer 将启动一个非守护程序调度程序线程，该线程将在 HttpServer#stop 被调用时退出，所以我面临死锁。
non-daemon thread not finish -> shutdown hook not triggered -> can't stop server -> non-daemon thread not finish
有什么好主意吗？请注意我无法修改定位应用程序的代码。
应用 kriegaex 的答案后更新
I added some logging to watch dog thread, and here is outputs:
2021-09-22 17:30:00.967 INFO - Connnection@1594791957 acquired by 40A4F128987F8BD9C0EE6749895D1237
2021-09-22 17:30:00.968 DEBUG - Stack@40A4F128987F8BD9C0EE6749895D1237:
java.lang.Throwable:
at com.zaxxer.hikari.pool.ProxyConnection.<init>(ProxyConnection.java:102)
at com.zaxxer.hikari.pool.HikariProxyConnection.<init>(HikariProxyConnection.java)
at com.zaxxer.hikari.pool.ProxyFactory.getProxyConnection(ProxyFactory.java)
at com.zaxxer.hikari.pool.PoolEntry.createProxyConnection(PoolEntry.java:97)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:192)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:162)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:100)
at agenttest.AgentTest.main(AgentTest.java:19)
2021-09-22 17:30:00.969 INFO - Connnection@686560878 acquired by 464555C270688B747CA211DE489B7730
2021-09-22 17:30:00.969 DEBUG - Stack@464555C270688B747CA211DE489B7730:
java.lang.Throwable:
at com.zaxxer.hikari.pool.ProxyConnection.<init>(ProxyConnection.java:102)
at com.zaxxer.hikari.pool.HikariProxyConnection.<init>(HikariProxyConnection.java)
at com.zaxxer.hikari.pool.ProxyFactory.getProxyConnection(ProxyFactory.java)
at com.zaxxer.hikari.pool.PoolEntry.createProxyConnection(PoolEntry.java:97)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:192)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:162)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:100)
at agenttest.AgentTest.main(AgentTest.java:20)
2021-09-22 17:30:00.971 DEBUG - Connnection@1594791957 used by getMetaData
2021-09-22 17:30:01.956 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:01.956 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:02.956 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:02.956 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:03.957 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:03.957 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:04.959 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:04.959 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:05.959 DEBUG - there is still 12 active threads, keep wathcing
2021-09-22 17:30:05.960 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true HikariPool-1 connection adder#true
2021-09-22 17:30:06.960 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:06.960 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:07.961 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:07.961 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:08.961 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:08.961 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:09.962 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:09.962 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:10.962 DEBUG - there is still 11 active threads, keep wathcing
2021-09-22 17:30:10.963 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true main#false server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true HikariPool-1 housekeeper#true
2021-09-22 17:30:10.976 INFO - Connnection@1594791957 released
2021-09-22 17:30:10.976 DEBUG - set connection count to 0 by stack hash 40A4F128987F8BD9C0EE6749895D1237
2021-09-22 17:30:10.976 INFO - Connnection@686560878 released
2021-09-22 17:30:10.976 DEBUG - set connection count to 0 by stack hash 464555C270688B747CA211DE489B7730
2021-09-22 17:30:11.963 DEBUG - there is still 10 active threads, keep wathcing
2021-09-22 17:30:11.963 DEBUG - Reference Handler#true Finalizer#true Signal Dispatcher#true server-timer#true Thread-2#false jdbcld-watch-dog#false Timer-0#true oracle.jdbc.driver.BlockSource.ThreadedCachingBlockSource.BlockReleaser#true InterruptTimer#true DestroyJavaVM#false
2021-09-22 17:30:12.964 DEBUG - there is still 10 active threads, keep wathcing
更新
我想支持所有类型的 java 应用程序，包括 Web 应用程序 运行 servlet 容器和单独的标准 javase 应用程序。
这里有一点 MCVE 说明 ewrammer 的想法。我使用 byte-buddy-agent 小助手库来动态附加代理，以便使我的示例自包含，从 main 方法直接启动 Java 代理。我省略了 运行 这个例子所必需的 3 个简单的空操作虚拟处理程序 类。
package org.acme.agent;
import com.sun.net.httpserver.HttpServer;
import net.bytebuddy.agent.ByteBuddyAgent;
import java.io.IOException;
import java.lang.instrument.Instrumentation;
import java.net.InetSocketAddress;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
public class Agent {
public static void premain(String agentArgs, Instrumentation inst) throws IOException {
HttpServer httpServer = HttpServer.create(new InetSocketAddress(8000), 0);
ExecutorService executorService = getExecutorService(httpServer);
Runtime.getRuntime().addShutdownHook(getShutdownHook(httpServer, executorService));
// other instrumention code ignored ...
startWatchDog();
}
private static ExecutorService getExecutorService(HttpServer server) {
server.createContext("/report", new ReportHandler());
server.createContext("/data", new DataHandler());
server.createContext("/stack", new StackHandler());
ExecutorService executorService = Executors.newCachedThreadPool(new ThreadFactory() {
int count = 0;
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setName("JDBCLD-HTTP-SERVER" + count++);
return t;
}
});
server.setExecutor(executorService);
server.start();
return executorService;
}
private static Thread getShutdownHook(HttpServer httpServer, ExecutorService executorService) {
return new Thread(() -> {
httpServer.stop(5);
System.out.println("Internal HTTP server has been stopped");
executorService.shutdown();
try {
if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
System.out.println("Executor service of internal HTTP server not closing in 60 seconds");
executorService.shutdownNow();
if (!executorService.awaitTermination(60, TimeUnit.SECONDS))
System.out.println("Executor service of internal HTTP server not closing in 120 seconds, giving up");
}
else {
System.out.println("Executor service of internal HTTP server closed");
}
}
catch (InterruptedException ie) {
System.out.println("Thread interrupted, shutting down executor service of internal HTTP server");
executorService.shutdownNow();
Thread.currentThread().interrupt();
}
});
}
private static void startWatchDog() {
ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
while (threadGroup.getParent() != null)
threadGroup = threadGroup.getParent();
final ThreadGroup topLevelThreadGroup = threadGroup;
// Plus 1, because of the monitoring thread we are going to start right below
final int activeCount = topLevelThreadGroup.activeCount() + 1;
new Thread(() -> {
do {
try {
Thread.sleep(1000);
}
catch (InterruptedException ignored) {}
} while (topLevelThreadGroup.activeCount() > activeCount);
System.exit(0);
}).start();
}
public static void main(String[] args) throws IOException {
premain(null, ByteBuddyAgent.install());
Random random = new Random();
for (int i = 0; i < 5; i++) {
new Thread(() -> {
int threadDurationSeconds = 1 + random.nextInt(10);
System.out.println("Starting thread with duration " + threadDurationSeconds + " s");
try {
Thread.sleep(threadDurationSeconds * 1000);
System.out.println("Finishing thread after " + threadDurationSeconds + " s");
}
catch (InterruptedException ignored) {}
}).start();
}
}
}
如您所见，这基本上是您的示例代码，重构为几个辅助方法以提高可读性，以及新的看门狗方法。非常简单。
这会生成如下控制台日志：
Starting thread with duration 6 s
Starting thread with duration 6 s
Starting thread with duration 8 s
Starting thread with duration 7 s
Starting thread with duration 5 s
Finishing thread after 5 s
Finishing thread after 6 s
Finishing thread after 6 s
Finishing thread after 7 s
Finishing thread after 8 s
internal httpserver has been closed.
executor service of internal httpserver closed.