Nginx支持socket转发

有个接口是通过socket通信,对端服务器访问存在IP限制,只好通过跳板机,因为它具备访问对端服务器的权限。nginx1.9开始支持tcp层的转发,通过stream实现的,而socket也是基于tcp通信。

一.实现过程:

1.安装nginx,stream模块默认不安装的,需要手动添加参数:–with-stream,官方下载地址:download,根据自己系统版本选择nginx1.9或以上版本。

2.nginx.conf 配置,参考说明:ngx_stream_core_module

nginx.conf

user nginx;
worker_processes 1;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
……………..
}

# tcp层转发的配置文件夹

include /etc/nginx/tcp.d/*.conf;
请注意,stream配置不能放到http内,即不能放到/etc/nginx/conf.d/,因为stream是通过tcp层转发,而不是http转发。

如配置在http内,启动nginx会报如下错误:

nginx: [emerg] “server” directive is not allowed here
3.在tcp.d下新建个bss_num_30001.conf文件,内容如下:

Spring框架简介

1. Spring框架的作用

轻量:Spring是轻量级的,基本的版本大小为2MB
控制反转:Spring通过控制反转实现了松散耦合,对象们给出它们的依赖,而不是创建或查找依赖的对象们。
面向切面的编程AOP:Spring支持面向切面的编程,并且把应用业务逻辑和系统服务分开。
容器:Spring包含并管理应用中对象的生命周期和配置
MVC框架: Spring-MVC
事务管理:Spring提供一个持续的事务管理接口,可以扩展到上至本地事务下至全局事务JTA
异常处理:Spring提供方便的API把具体技术相关的异常

tx:annotation-driven注解方式EnableTransactionManagement

替换方法是用@EnableTransactionManagement

以下是官方文档:

org.springframework.transaction.annotation
Annotation Type EnableTransactionManagement


@Target(value=TYPE)
@Retention(value=RUNTIME)
@Documented
@Import(value=TransactionManagementConfigurationSelector.class)
public @interface EnableTransactionManagement

Enables Spring’s annotation-driven transaction management capability, similar to the support found in Spring’s <tx:*> XML namespace. To be used on @Configuration classes as follows:

 @Configuration
 @EnableTransactionManagement
 public class AppConfig {
     @Bean
     public FooRepository fooRepository() {
         // configure and return a class having @Transactional methods
         return new JdbcFooRepository(dataSource());
     }

     @Bean
     public DataSource dataSource() {
         // configure and return the necessary JDBC DataSource
     }

     @Bean
     public PlatformTransactionManager txManager() {
         return new DataSourceTransactionManager(dataSource());
     }
 }

For reference, the example above can be compared to the following Spring XML configuration:

 <beans>
     <tx:annotation-driven/>
     <bean id="fooRepository" class="com.foo.JdbcFooRepository">
         <constructor-arg ref="dataSource"/>
     </bean>
     <bean id="dataSource" class="com.vendor.VendorDataSource"/>
     <bean id="transactionManager" class="org.sfwk...DataSourceTransactionManager">
         <constructor-arg ref="dataSource"/>
     </bean>
 </beans>
 

In both of the scenarios above, @EnableTransactionManagement and <tx:annotation-driven/> are responsible for registering the necessary Spring components that power annotation-driven transaction management, such as the TransactionInterceptor and the proxy- or AspectJ-based advice that weave the interceptor into the call stack when JdbcFooRepository‘s @Transactional methods are invoked.

A minor difference between the two examples lies in the naming of the PlatformTransactionManager bean: In the @Bean case, the name is “txManager” (per the name of the method); in the XML case, the name is“transactionManager”. The <tx:annotation-driven/> is hard-wired to look for a bean named “transactionManager” by default, however @EnableTransactionManagement is more flexible; it will fall back to a by-type lookup for anyPlatformTransactionManager bean in the container. Thus the name can be “txManager”, “transactionManager”, or “tm”: it simply does not matter.

For those that wish to establish a more direct relationship between @EnableTransactionManagement and the exact transaction manager bean to be used, the TransactionManagementConfigurer callback interface may be implemented – notice the implements clause and the @Override-annotated method below:

 @Configuration
 @EnableTransactionManagement
 public class AppConfig implements TransactionManagementConfigurer {
     @Bean
     public FooRepository fooRepository() {
         // configure and return a class having @Transactional methods
         return new JdbcFooRepository(dataSource());
     }

     @Bean
     public DataSource dataSource() {
         // configure and return the necessary JDBC DataSource
     }

     @Bean
     public PlatformTransactionManager txManager() {
         return new DataSourceTransactionManager(dataSource());
     }

     @Override
     public PlatformTransactionManager annotationDrivenTransactionManager() {
         return txManager();
     }
 }

This approach may be desirable simply because it is more explicit, or it may be necessary in order to distinguish between two PlatformTransactionManager beans present in the same container. As the name suggests, theannotationDrivenTransactionManager() will be the one used for processing @Transactional methods. See TransactionManagementConfigurer Javadoc for further details.

The mode() attribute controls how advice is applied; if the mode is AdviceMode.PROXY (the default), then the other attributes control the behavior of the proxying.

If the mode() is set to AdviceMode.ASPECTJ, then the proxyTargetClass() attribute is obsolete. Note also that in this case the spring-aspects module JAR must be present on the classpath.

Since:
3.1
Author:
Chris Beams
See Also:
TransactionManagementConfigurer, TransactionManagementConfigurationSelector, ProxyTransactionManagementConfiguration, AspectJTransactionManagementConfiguration

Optional Element Summary
 AdviceMode mode
Indicate how transactional advice should be applied.
 int order
Indicate the ordering of the execution of the transaction advisor when multiple advices are applied at a specific joinpoint.
 boolean proxyTargetClass
Indicate whether subclass-based (CGLIB) proxies are to be created (true) as opposed to standard Java interface-based proxies (false).

 

proxyTargetClass

public abstract boolean proxyTargetClass
Indicate whether subclass-based (CGLIB) proxies are to be created (true) as opposed to standard Java interface-based proxies (false). The default is false. Applicable only if mode() is set to AdviceMode.PROXY.Note that setting this attribute to true will affect all Spring-managed beans requiring proxying, not just those marked with @Transactional. For example, other beans marked with Spring’s @Async annotation will be upgraded to subclass proxying at the same time. This approach has no negative impact in practice unless one is explicitly expecting one type of proxy vs another, e.g. in tests.

Default:
false

mode

public abstract AdviceMode mode
Indicate how transactional advice should be applied. The default is AdviceMode.PROXY.
See Also:
AdviceMode
Default:
org.springframework.context.annotation.AdviceMode.PROXY

order

public abstract int order
Indicate the ordering of the execution of the transaction advisor when multiple advices are applied at a specific joinpoint. The default is Ordered.LOWEST_PRECEDENCE.
Default:
2147483647

 

https://docs.spring.io/spring/docs/4.0.x/javadoc-api/org/springframework/transaction/annotation/EnableTransactionManagement.html

更多文档:

https://docs.spring.io/spring/docs/4.0.x/javadoc-api/overview-summary.html

Nginx使用upstream模块实现tomcat负载均衡

UPSTREAM负载均衡模块

负载均衡模块用于从”upstream”指令定义的后端主机列表中选取一台主机。nginx先使用负载均衡模块找到一台主机,再使用upstream模块实现与这台主机的交互。为了方便介绍负载均衡模块,做到言之有物,以下选取nginx内置的ip hash模块作为实际例子进行分析。

配置

要了解负载均衡模块的开发方法,首先需要了解负载均衡模块的使用方法。因为负载均衡模块与之前书中提到的模块差别比较大,所以我们从配置入手比较容易理解。

在配置文件中,我们如果需要使用ip hash的负载均衡算法。我们需要写一个类似下面的配置:

Java多线程,线程池ThreadPoolExecutor使用详解

ThreadPoolExecutor.class构造方法参数讲解

参数名 作用
corePoolSize 核心线程池大小
maximumPoolSize 最大线程池大小
keepAliveTime 线程池中超过corePoolSize数目的空闲线程最大存活时间;可以allowCoreThreadTimeOut(true)使得核心线程有效时间
TimeUnit keepAliveTime时间单位
workQueue 阻塞任务队列
threadFactory 新建线程工厂
RejectedExecutionHandler 当提交任务数超过maxmumPoolSize+workQueue之和时,任务会交给RejectedExecutionHandler来处理

1.当线程池小于corePoolSize时,新提交任务将创建一个新线程执行任务,即使此时线程池中存在空闲线程。
2.当线程池达到corePoolSize时,新提交任务将被放入workQueue中,等待线程池中任务调度执行
3.当workQueue已满,且maximumPoolSize>corePoolSize时,新提交任务会创建新线程执行任务
4.当提交任务数超过maximumPoolSize时,新提交任务由RejectedExecutionHandler处理
5.当线程池中超过corePoolSize线程,空闲时间达到keepAliveTime时,关闭空闲线程
6.当设置allowCoreThreadTimeOut(true)时,线程池中corePoolSize线程空闲时间达到keepAliveTime也将关闭

示例代码:

import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class testThreadPool {

   /**
    * 线程计数 
    */
   private static int count = 0;
   public static void main(String[] args) {
      
      /**
       * 通常会使用一个队列,进行排序
       */
      BlockingQueue<Runnable> queue = new ArrayBlockingQueue<>(25);
      
      /**
       * 如果使用无界的队列,当出现攻击时,容易导致内存泄漏。
       */
      //LinkedBlockingDeque<Runnable> queue = new LinkedBlockingDeque<>();
      
      /**
       * 线程池
       */
      ThreadPoolExecutor pool = new ThreadPoolExecutor(5, 10, 30, TimeUnit.MINUTES, queue);
      
      /**
       * 重写Handler抛出来的线程重新加进去
       */
      pool.setRejectedExecutionHandler(new RejectedExecutionHandler() {
         
         @Override
         public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
            // TODO Auto-generated method stub
            while (true) {
               if (queue.size() < 24) {
                  System.out.println("++++++++++++++Runnable");
                  executor.execute(r);
                  break;
               }
            }
         }
      });

      /**
       * 定义一个定时器,每2秒创建10个进程
       */
      Timer timer = new Timer();
      timer.schedule(new TimerTask() {
         
         @Override
         public void run() {
            // TODO Auto-generated method stub
            
            for(int i = 0;i<10;i++) {
               count++;
               doWork work = new doWork();
               pool.execute(work);
               
            }
            
            if (count >= 200) {
               timer.cancel();
            }
         }
      }, 0,2000);
      
      /**
       * 定时检查线程的状况
       */
      new Timer().schedule(new TimerTask() {
         @Override
         public void run() {
            // TODO Auto-generated method stub
            System.err.println(">>当前队列:"+queue.size());
            System.err.println(">>线程数:"+count);
            System.err.println(">>当前ActiveCount:"+pool.getActiveCount());
            System.err.println(">>当前TaskCount:"+pool.getTaskCount());
            System.err.println(">>当前PoolSize:"+pool.getPoolSize());
         }
      }, 1000,1000);
      
   }
}

class doWork implements Runnable{
   

   @Override
   public void run() {
      // TODO Auto-generated method stub
      
      try {
         /**
          * 模拟真实环境,睡眠3秒
          */
         Thread.sleep(3000);
         System.out.println("线程id:"+Thread.currentThread().getId()+" 线程名称:"+Thread.currentThread().getName());
      } catch (InterruptedException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }
      
   }

}

 

API文档:

http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ThreadPoolExecutor.html

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