如果使用的是Spring Boot Actuator的shutdown端点来关闭Spring Boot应用程序，则可能会遇到这个问题。在某些情况下，shutdown端点不能停止Java进程，因为线程还在运行，或者有其他的资源没有正确地关闭。

为了解决这个问题，我们可以尝试使用优雅关闭的方法，即在应用程序关闭之前优雅地关闭所有线程和资源。下面是一个简单的代码示例，展示了如何优雅地关闭Spring Boot应用程序：

@Configuration
public class GracefulShutdownConfiguration {

    @Bean
    public GracefulShutdown gracefulShutdown() {
        return new GracefulShutdown();
    }

    @Bean
    public GracefulShutdownTomcatConnectorCustomizer gracefulShutdownTomcatConnectorCustomizer(GracefulShutdown gracefulShutdown) {
        return new GracefulShutdownTomcatConnectorCustomizer(gracefulShutdown);
    }

}

public class GracefulShutdown implements TomcatConnectorCustomizer, ApplicationListener {

    private volatile Connector connector;

    @Override
    public void customize(Connector connector) {
        this.connector = connector;
    }

    @Override
    public void onApplicationEvent(ContextClosedEvent event) {
        this.connector.pause();
        Executor executor = this.connector.getProtocolHandler().getExecutor();
        if (executor instanceof ThreadPoolExecutor) {
            try {
                ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executor;
                threadPoolExecutor.shutdown();
                if (!threadPoolExecutor.awaitTermination(30, TimeUnit.SECONDS)) {
                    System.err.println("Tomcat thread pool did not shut down gracefully within 30 seconds. Proceeding with forceful shutdown");
                }
            } catch (InterruptedException ex) {
                Thread.currentThread().interrupt();
            }
        }
    }
}

public class GracefulShutdownTomcatConnectorCustomizer implements TomcatConnectorCustomizer {

    private final GracefulShutdown gracefulShutdown;

    public GracefulShutdownTomcatConnectorCustomizer(GracefulShutdown gracefulShutdown) {
        this.gracefulShutdown = gracefulShutdown;
    }

    @Override
    public void customize(Connector connector) {
        this.gracefulShutdown.customize(connector);
    }
}