在很多项目中，有一些数据量不小，但是也不是很大的，且数据更新频率很小的数据
这种情况下我们一般会自己缓存这些数据，现在我们使用spring+quartz的方式来处理，
即以定时更新这部分数据，以达到在某个时段可以重复使用内存缓存数据，不必访问数据库或者其它直接数据源
先定义一个任务类，以执行定时更新操作，这里从数据库查询一个国家，城市数据作为一个类的静态成员数据
这个任务类：AreaCodeJob.java
package com.fruitking.cache.job;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
import org.springframework.scheduling.quartz.QuartzJobBean;
import com.fruitking.entity.Country;
import com.fruitking.entity.City;
import com.fruitking.service.IAreaCodeService;
public class AreaCodeJob extends QuartzJobBean{
private static final Log log = LogFactory.getLog(AreaCodeJob.class);
private IAreaCodeService areaCodeService;
public void setAreaCodeService(IAreaCodeService areaCodeService) {
this.areaCodeService = areaCodeService;
}
protected void executeInternal(JobExecutionContext arg0)throws JobExecutionException {
try {
long changeMemory = Runtime.getRuntime().freeMemory();
//为了获取所有国家信息
List<Country> countryCodeList = areaCodeService.findCountrys();
//为了获取所有城市信息
List<City> cityCodeList = areaCodeService.findCitys();
//更新缓存内容
DBDataCacheContext.setCountryCodeList(countryCodeList);
DBDataCacheContext.setCityCodeList(cityCodeList);
if(log.isInfoEnabled()){
long freeMemory = Runtime.getRuntime().freeMemory();
long maxMemory = Runtime.getRuntime().maxMemory();
long totalMemory = Runtime.getRuntime().totalMemory();
changeMemory = changeMemory - freeMemory;
String jvmIndf = "start to end...jvm free memory change:"+changeMemory+"B also:"+(changeMemory/1024)+"KB,free memory is:"+freeMemory + ",total memory is:"+totalMemory+",max memory is:"+maxMemory;
log.info(jvmIndf);
}
} catch (Exception e) {
log.error(e.getMessage(), e);
}
}
}
缓存类的编写DBDataCacheContext.java
package com.fruitking.cache.job;
import java.util.List;
import com.fruitking.entity.Country;
import com.fruitking.entity.City;
public class DBDataCacheContext {
private static List<Country> countryCodeList = null;//所有国家信息
private static List<City> cityCodeList = null;//所有城市信息
public static List<Country> getCountryCodeList() {
return countryCodeList;
}
public static void setCountryCodeList(
List<Country> countryCodeList) {
DBDataCacheContext.countryCodeList = null;
DBDataCacheContext.countryCodeList = countryCodeList;
}
public static List<City> getCityCodeList() {
return cityCodeList;
}
public static void setCityCodeList(
List<City> cityCodeList) {
DBDataCacheContext.cityCodeList = null;
DBDataCacheContext.cityCodeList = cityCodeList;
}
}
spring的定时配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">
<!--spring定时触发， Quartz 配置-->
<!-- 定时更新折扣信息 -->
<bean id="areaCodeJob" class="org.springframework.scheduling.quartz.JobDetailBean">
<property name="jobClass">
<value>com.fruitking.cache.job.AreaCodeJob</value>
</property>
<property name="jobDataAsMap">
<map>
<entry key="areaCodeService"><ref bean="areaCodeService"/></entry>
</map>
</property>
</bean>
<bean id="areaCodeJobTrigger" class="org.springframework.scheduling.quartz.CronTriggerBean">
<property name="jobDetail">
<ref bean="areaCodeJob"/>
</property>
<property name="cronExpression">
<!--eg: 每小时整点跟新一次,表达式为"0 0 * * * ?" -->
<value>0/5 * * * * ?</value>
</property>
</bean>
<!-- 触发器调度控制器 -->
<bean class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
<property name="triggers">
<list>
<ref bean="areaCodeJobTrigger"/>
</list>
</property>
</bean>
</beans>
这样就可以在其它类里面使用这个国家，城市信息数据了，直接当静态数据使用，这样就大大提高了速度
log4j.properties配置文件设置一下
log4j.rootLogger=error,stdout
log4j.appender.stdout.layout.ConversionPattern=%-d{HH:mm:ss} - %m%n
log4j.logger.com.fruitking.cache.job=info
这样启动相应工程，观察jvm的内存变化
我这里的数据量大约在7000条左右，按照字节算应该在12M左右的数据量，但是通过jvm观察，内存实际一次增加15-20M
我想这可能是程序执行过程的局部变量产生的吧
我这里为了测试每5秒钟更新一次数据，实际使用中可能每半小时，每小时，甚至每天，一周才更新一次数据，可以通过corn表达式配置
运行的jvm内存数据变化如下：
10:20:53 - start to end...jvm free memory change:-8535944B also:-8335KB,free memory is:464688232
10:20:58 - start to end...jvm free memory change:20714696B also:20229KB,free memory is:442974016
10:21:02 - start to end...jvm free memory change:18470480B also:18037KB,free memory is:423619808
10:21:07 - start to end...jvm free memory change:21115288B also:20620KB,free memory is:429755752
10:21:12 - start to end...jvm free memory change:18710776B also:18272KB,free memory is:409949680
10:21:17 - start to end...jvm free memory change:-7640992B also:-7461KB,free memory is:416865832
10:21:22 - start to end...jvm free memory change:20315064B also:19838KB,free memory is:395625680
10:21:27 - start to end...jvm free memory change:19071784B also:18624KB,free memory is:375837648
10:21:32 - start to end...jvm free memory change:-7389080B also:-7215KB,free memory is:382382832
10:21:37 - start to end...jvm free memory change:19783216B also:19319KB,free memory is:361913736
10:21:42 - start to end...jvm free memory change:-5315160B also:-5190KB,free memory is:366734176
10:21:47 - start to end...jvm free memory change:20523832B also:20042KB,free memory is:345657112
10:21:52 - start to end...jvm free memory change:19157344B also:18708KB,free memory is:325855784
10:21:57 - start to end...jvm free memory change:-7493720B also:-7318KB,free memory is:332798168
10:22:02 - start to end...jvm free memory change:20266552B also:19791KB,free memory is:311923072
10:22:07 - start to end...jvm free memory change:19279584B also:18827KB,free memory is:292246632
10:22:12 - start to end...jvm free memory change:-7546800B also:-7369KB,free memory is:299198448
10:22:17 - start to end...jvm free memory change:19976304B also:19508KB,free memory is:278662488
10:22:22 - start to end...jvm free memory change:-7270136B also:-7099KB,free memory is:285511848
10:22:27 - start to end...jvm free memory change:20545944B also:20064KB,free memory is:264410968
10:22:32 - start to end...jvm free memory change:19383184B also:18928KB,free memory is:244694904
10:22:37 - start to end...jvm free memory change:-7212344B also:-7043KB,free memory is:251415320
10:22:42 - start to end...jvm free memory change:19974280B also:19506KB,free memory is:230890280
10:22:47 - start to end...jvm free memory change:18752272B also:18312KB,free memory is:209553416
10:22:52 - start to end...jvm free memory change:-7150144B also:-6982KB,free memory is:216190760
10:22:57 - start to end...jvm free memory change:19399488B also:18944KB,free memory is:196329776
10:23:02 - start to end...jvm free memory change:-7469600B also:-7294KB,free memory is:203393160
10:23:07 - start to end...jvm free memory change:20435936B also:19956KB,free memory is:182441944
10:23:12 - start to end...jvm free memory change:19334896B also:18881KB,free memory is:162776104
10:23:17 - start to end...jvm free memory change:-7098288B also:-6931KB,free memory is:169379904
10:23:22 - start to end...jvm free memory change:20187808B also:19714KB,free memory is:148749040
10:23:27 - start to end...jvm free memory change:19275120B also:18823KB,free memory is:129105136
10:23:32 - start to end...jvm free memory change:-6974952B also:-6811KB,free memory is:135752520
10:23:37 - start to end...jvm free memory change:19390936B also:18936KB,free memory is:115898104
10:23:42 - start to end...jvm free memory change:-7392224B also:-7218KB,free memory is:122888592
10:23:47 - start to end...jvm free memory change:20411232B also:19932KB,free memory is:101997272
10:23:52 - start to end...jvm free memory change:19200584B also:18750KB,free memory is:82457368
10:23:57 - start to end...jvm free memory change:-6989048B also:-6825KB,free memory is:88964600
10:24:02 - start to end...jvm free memory change:20093744B also:19622KB,free memory is:68436232
10:24:07 - start to end...jvm free memory change:19069808B also:18622KB,free memory is:48973840
10:24:12 - start to end...jvm free memory change:-6860432B also:-6699KB,free memory is:55555312
10:24:17 - start to end...jvm free memory change:19083904B also:18636KB,free memory is:35998224
10:24:22 - start to end...jvm free memory change:-7115224B also:-6948KB,free memory is:42700944
10:24:27 - start to end...jvm free memory change:20389944B also:19912KB,free memory is:21828952,total memory is:532807680,max memory is:1065484288
10:24:33 - start to end...jvm free memory change:-396309648B also:-387021KB,free memory is:417800024,total memory is:532807680,max memory is:1065484288
10:24:37 - start to end...jvm free memory change:-3880768B also:-3789KB,free memory is:421199168,total memory is:532807680,max memory is:1065484288
10:24:42 - start to end...jvm free memory change:20413072B also:19934KB,free memory is:400347744
10:24:47 - start to end...jvm free memory change:-5273152B also:-5149KB,free memory is:403160512
10:24:52 - start to end...jvm free memory change:20586320B also:20103KB,free memory is:382110152
10:24:57 - start to end...jvm free memory change:19145032B also:18696KB,free memory is:362503656
这里从中可以总结几点：
1。随着数据的加载，jvm内存使用量不断增加，每次近20M（因为这个数据很大），这个比我想的要夸张点
2。jvm内存的回收绝大部分实在内存可使用量很低的时候才大量回收垃圾数据，其它时候虽然偶尔也回收，回收幅度很小
3。总的内存数量和最大内存数量值没有变化
分享到：
相关推荐
JAVA应用JVM原理及参数调优深入讲解视频.1 JAVA应用JVM原理及参数调优深入讲解视频.2 JAVA应用JVM原理及参数调优深入讲解视频.3 JAVA应用JVM原理及参数调优深入讲解视频.4 JAVA应用JVM原理及参数调优深入讲解视频.5 ...
当前，以Hadoop、Spark为代表的大数据处理框架，已经在学术界和工业界被广泛应用于大规模数据的处理和分析.这些大数据处理框架采用分布式架构，使用Java、Scala等面向对象语言编写，在集群节点上以Java虚拟机（JVM）...
学习关于JVM基础，java内模型的全面透析，Jar hell问题以及解决办法，Class文件格式 • Java编译执行流程 • ClassFile的格式介绍 • ClassFile中FieldInfo和MethodInfo介绍 • 类型描述Descriptor介绍 • ClassFile...
jvm 配置jvm参数 配置jvm参数
JVM问题定位的典型案例分析
原文链接：https://blog.csdn.net/m0_37814112/article/details/119028528 说明：Kubernetes集群之微服务JVM内存监控，prometheus服务yaml文件
对jvm的一个总括
1.8 JVM调优总结（七）-典型配置举例 1.9 JVM调优总结（八）-典型配置举例2 31 1.10 JVM调优总结（九）-新一代的垃圾回收算法34 1.11 JVM调优总结（十）-调优方法38 1.12 JVM调优总结（十一）-反思
仿redis缓存Java版轻量级缓存组件LocalCache，基于JVM内存实现数据缓存及过期机制
jvm开发实战项目案例分析
JAVA应用JVM原理及参数调优深入讲解视频,内容讲解透彻，内容丰富
jvm源码
JVM介绍入门到深入，通过全面了解JVM组成底层工作原理以及数据结构，在今后JVM深入分析中全面提升运行性能
这是Java学习过程中整理搜集的关于JVM，多线程，数据结构，集合的思维导图，能够有效的进行系统的学习
zabbix自动发现JAVA进程，并进行自动添加监控JAVA 进程的JVM数据，统计分析告警监控。 支持多种中间件，tomcat、weblogic、微服务方式部署JAVA应用监控。 自带发现脚本和监控脚本，以及zabbix导入模板。
JVM启动参数应用集合
jvm
java基础之JVM，jvm是java的核心技术，也是面试过程中经常出现的
jvm源码，jvm-native的源码,jvm支行机制,可对jvm的运行过程进行分析 个人网站：https://www.zhangjunbk.com