写在前面
主要介绍sentinel的限流熔断如何使用，如何与api网关进行整合，以及其dashboard的使用等；
sentinel 地址 /alibaba/Sentinel
sentinel dashboard地址 /alibaba/Sentinel/tree/master/sentinel-dashboard
sentinel wiki地址 /alibaba/Sentinel/wiki
littlehow-sentinel接入指南地址
sentinel在普通项目中使用
- 需要引入其依赖包(此处以version=1.6.1举例)
<properties>
<>1.6.1</>
</properties>
<dependency>
<groupId></groupId>
<artifactId>sentinel-core</artifactId>
<version>${}</version>
</dependency>
限流使用
限流详细文档地址：/alibaba/Sentinel/wiki/%E6%B5%81%E9%87%8F%E6%8E%A7%E5%88%B6
下面举个简单的使用示例：
- 限流简单配置代码
/**
* 基于QPS的资源限流
* @param name -- 资源名称
* @param count -- 数量
*/
public static void flowRule(String name, int count) {
//限流规则，可以多个flow rule,该规则支持QPS和并发线程数的限流
//()可以获取到已经设置的限流规则
List<FlowRule> rules = new ArrayList<>();
FlowRule rule = new FlowRule();
//设置资源名称，sentinel限流都是以资源为单位进行
rule.setResource(name);
//使用QPS限流
rule.setGrade(RuleConstant.FLOW_GRADE_QPS);
//QPS达到的数量阈值
rule.setCount(count);
rules.add(rule);
//重新加载限流规则，此处将覆盖原有的限流，所以如果想要不覆盖
//请使用()获取到的加入到rules中
FlowRuleManager.loadRules(rules);
}
- 限流使用示例如下：
public static void main(String[] args) {
//执行限流
flow("sayHello", 3);
}
public static void flow(String resourceName, int count) {
// 配置规则,每秒可以过3个hello world的请求
flowRule(resourceName, count);
while (true) {
for (int i = 0; i <= count; i++) {
//entry这里是关键逻辑，它会基于滑动时间窗口来进行限流统计；
//所以此处才是限流的关键
try (Entry entry = SphU.entry(resourceName)) {
sayHello("" + (int)entry.getCurNode().successQps());
} catch (BlockException ex) {
// 处理被流控的逻辑
System.out.println("blocked!");
}
}
sleepSeconds(1);
}
}
//需要限流的方法
public static void sayHello(String info) {
System.out.println("hello world! before success count = " + info);
}
//按秒睡眠
private static void sleepSeconds(long time) {
try {
TimeUnit.SECONDS.sleep(time);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
运行上面的代码后，输出结果如下(从结果可以发现，程序以恒定每秒4次来调用被限流的方法，而配置中方法能支持的QPS为3次，所以每次调用都会有一次被保护，从而走限流分支，在限流分支中可以写自己的业务逻辑)：
hello world! before success count = 0
hello world! before success count = 1
hello world! before success count = 2
blocked!
hello world! before success count = 0
hello world! before success count = 1
hello world! before success count = 2
blocked!
hello world! before success count = 0
hello world! before success count = 1
hello world! before success count = 2
熔断使用
- 熔断规则配置代码:
/**
* 熔断降级规则配置
* @param name -- 资源名称
* @param count -- 数量
*/
public static void degradeRule(String name, int count) {
//降级规则，可以多个degradeRule rule
//()可以获取到已经设置的降级规则
List<DegradeRule> rules = new ArrayList<>();
DegradeRule rule = new DegradeRule();
//设置资源名称，sentinel降级都是以资源为单位进行
rule.setResource(name);
//使用异常统计降级,分钟统计,滑动时间窗口
rule.setGrade(RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT);
//异常数达到的数量阈值
rule.setCount(count);
//秒级时间窗口,该值必须有且必须大于零，否则降级将无法生效
rule.setTimeWindow(10);
rules.add(rule);
//重新加载限流规则，此处将覆盖原有的限流，所以如果想要不覆盖
//请使用()获取到的加入到rules中
DegradeRuleManager.loadRules(rules);
}
- 熔断测试调用代码:
限流代码中的main调用degrade方法即可
public static void degrade(String resourceName, int count) {
// 配置熔断规则，发生count个异常即将进行熔断
degradeRule(resourceName, count * 2);
int sum = 0;
while (true) {
for (int i = 0; i <= count; i++) {
//所以此处才是限流的关键
Entry entry = null;
try {
entry = SphU.entry(resourceName);
sayHello(++sum + "");
} catch (BlockException e) {
System.out.println("被降级了:" + e);
} catch (Exception ex) {
// 处理业务异常,调用tracer才能统计异常数
Tracer.trace(ex);
} finally {
if (entry != null) {
entry.exit();
}
}
}
System.out.println("===============分割线================");
sleepSeconds(1);
}
}
public static void sayHello(String info) {
System.out.println("hello world! before success count = " + info);
throw new RuntimeException("test degrade");
}
运行代码后获得结果如下(在一分钟的滑动时间窗口下，异常超过6次则进行降级处理，直到时间窗口滑到小于6次异常才会继续被调用):
hello world! before success count = 1
hello world! before success count = 2
hello world! before success count = 3
hello world! before success count = 4
=分割线==
hello world! before success count = 5
hello world! before success count = 6
被降级了:
被降级了:
=分割线==
被降级了:
被降级了:
被降级了:
被降级了:
使用sentinel提供的aop集成限流降级
注解文档地址:/alibaba/Sentinel/wiki/%E6%B3%A8%E8%A7%A3%E6%94%AF%E6%8C%81
需要依赖springaop，使用springboot项目集成即可，前面的maven依赖不变，新增maven依赖如下:
<dependency>
<groupId></groupId>
<artifactId>sentinel-annotation-aspectj</artifactId>
<version>${}</version>
</dependency>
-
简单展示使用注解方式来进行限流降级(可以动态调整限流方案，也可以全局设置降级和限流处理类等)
-
待代用的测试服务:
其中fallback函数必须和原函数参数一致，handler函数可以增加一个异常的参数，其他参数保持不变。
@Service
public class SentinelAnnotationService {
@SentinelResource(value = "helloService", blockHandler = "myHandler", fallback = "myFallback")
public String sayHello(String name) {
if (System.currentTimeMillis() % 2 == 0) {
throw new RuntimeException("test");
}
return "return hello " + name;
}
public String myHandler(String name, BlockException ex) {
return "return handler " + name;
}
public String myFallback(String name) {
return "return fallback " + name;
}
}
- springboot调用类
@SpringBootApplication
public class Run {
public static void main(String[] args) {
ApplicationContext context = SpringApplication.run(Run.class, args);
test(context.getBean(SentinelAnnotationService.class));
}
/**
* 每10秒访问5次以上次
*/
private static void test(SentinelAnnotationService testService) {
//限流规则生成中
AddRule.flowRule("helloService", 3);
int sum = 10, total = sum;
while (sum-- > 0) {
for (int i = 1; i <= 5; i++) {
String result = testService.sayHello("littlehow" + i);
System.out.println("the " + (total - sum) + " result---->" + result);
}
sleepSeconds(10);
}
}
//按秒睡眠
private static void sleepSeconds(long time) {
try {
TimeUnit.SECONDS.sleep(time);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 这里很重要，这里是sentinel实现注解限流降级最关键的地方
* @return
*/
@Bean
public SentinelResourceAspect sentinelResourceAspect() {
return new SentinelResourceAspect();
}
}
- 执行后结果如下:
执行结果的前三行输出是不确定的,因为异常是随机抛出的,概率为50%，抛出异常后，将执行fallback，后两行的输出证明每秒限流3次效果达到了；
the 1 result---->return hello littlehow1
the 1 result---->return hello littlehow2
the 1 result---->return fallback littlehow3
the 1 result---->return handler littlehow4
the 1 result---->return handler littlehow5
sentinel与api网关的集成
与api网关集成文档地址:/alibaba/Sentinel/wiki/%E4%B8%BB%E6%B5%81%E6%A1%86%E6%9E%B6%E7%9A%84%E9%80%82%E9%85%8D
sentinel与spring cloud gateway集成
因为当前springboot与springcloud版本为，所以暂时集成不了spring cloud gateway；以后版本升级后可以考虑进行集成；
sentinel与的集成
待续…
sentinel与的集成
目前sentinel官方还没实现与集成
sentinel dashboard使用
dashboard的使用文档地址:/alibaba/Sentinel/wiki/%E6%8E%A7%E5%88%B6%E5%8F%B0
sentinel规则管理
dashboard的生产实践地址:/alibaba/Sentinel/wiki/%E5%9C%A8%E7%94%9F%E4%BA%A7%E7%8E%AF%E5%A2%83%E4%B8%AD%E4%BD%BF%E7%94%A8-Sentinel
结合当前项目管理规则
sentinel提供了基于zk、apollo等配置中心来管理规则，基于apollo的规则需要项目内部写入自己的namespace，所以基于sentinel的扩展，自定义规则管理；
tips:也可以直接基于RuleManage进行改变
自定义规则改变不需要添加任何其他依赖，核心是sentinel提供的datasource接口，实现如下：
- 数据源公共处理类
@Slf4j
public abstract class CommonDataSource<T> extends AbstractDataSource<String, List<T>> {
private String typeName;
public CommonDataSource(RuleConverter<T> ruleConverter, String typeName) {
super(ruleConverter);
this.typeName = typeName;
}
@Override
public void close() throws Exception {
log.info("data source close");
}
/**
* 修改规则
* @throws Exception
*/
public void updateRules() {
String rules = null;
try {
//加载改变后的规则值
rules = this.readSource();
log.info("update rules {}, typeName={}", rules, typeName);
//将改变写入RuleManage中
this.getProperty().updateValue(this.parser.convert(rules));
} catch (Exception e) {
log.error("update rules {} fail, typeName={}", rules, typeName, e);
}
}
}
- 公共规则转换器
abstract class RuleConverter<T> implements Converter<String, List<T>> {
private static final List EMPTY_LIST = new ArrayList<>(0);
/**
* 判断是否为空
* @param value
*/
protected boolean isEmpty(String value) {
return null == value || "".equals(value) || "0".equals(value);
}
/**
* 创建flow规则
* @param info
* @return
*/
protected List<FlowRule> createFlowRule(String info) {
if (isEmpty(info)) {
return EMPTY_LIST;
}
List<FlowRule> flowRules = new ArrayList<>();
//解析出错将异常抛往上层,只简单配置resourceName,grade,count
for (String s : getRulesInfo(info)) {
String[] ruleInfo = getRuleInfo(s);
FlowRule rule = new FlowRule(ruleInfo[0].trim())
.setGrade(Integer.parseInt(ruleInfo[1]))
.setCount(Double.parseDouble(ruleInfo[2]));
flowRules.add(rule);
}
return flowRules;
}
protected List<DegradeRule> createDegradeRule(String info) {
if (isEmpty(info)) {
return EMPTY_LIST;
}
List<DegradeRule> degradeRules = new ArrayList<>();
//解析出错将异常抛往上层,只简单配置resourceName,grade,count,timeWindow
for (String s : getRulesInfo(info)) {
String[] ruleInfo = getRuleInfo(s);
DegradeRule rule = new DegradeRule(ruleInfo[0].trim())
.setGrade(Integer.parseInt(ruleInfo[1]))
.setCount(Double.parseDouble(ruleInfo[2]))
.setTimeWindow(Integer.parseInt(ruleInfo[3]));
degradeRules.add(rule);
}
return degradeRules;
}
private String[] getRulesInfo(String info) {
return info.trim().split("#");
}
private String[] getRuleInfo(String info) {
return info.trim().split(",");
}
}
- 限流规则转换器
@Slf4j
public class FlowRuleConverter extends RuleConverter<FlowRule> {
@Override
public List<FlowRule> convert(String s) {
log.info("update flow rule to {}", s);
return createFlowRule(s);
}
public static FlowRuleConverter create() {
return new FlowRuleConverter();
}
}
- 配置管理器
@Configuration
public class SentinelRuleConfig {
private static final String RULE_FLOW_KEY = "flow";
private static final String RULE_DEGRADE_KEY = "degrade";
private Map<String, String> rulesConfig = new HashMap<>();
private CommonDataSource<FlowRule> flowDataSource;
private CommonDataSource<DegradeRule> degradeDataSource;
public SentinelRuleConfig() {
super();
init();
}
/**
* 多个规则用;隔开，一个规则内部用,隔开
* 顺序为resourceName,grade,count
* 如helloService,1,3;sayBye,0,5
* grade参考如下
* @see
* @param rules
*/
@Value("${:helloService,1,3}")
private void setFlowRules(String rules) {
rulesConfig.put(RULE_FLOW_KEY, rules);
flowDataSource.updateRules();
}
/**
* 多个规则用;隔开，一个规则内部用,隔开
* 顺序为resourceName,grade,count,timeWindow
* 如helloService,1,3,10;sayBye,0,5,10
* grade参考如下
* @see
* @param rules
*/
@Value("${:}")
private void setDegradeRules(String rules) {
rulesConfig.put(RULE_DEGRADE_KEY, rules);
degradeDataSource.updateRules();
}
public void init() {
flowDataSource = new CommonDataSource<FlowRule>(FlowRuleConverter.create(), RULE_FLOW_KEY) {
@Override
public String readSource() {
return rulesConfig.get(RULE_FLOW_KEY);
}
};
//将新的数据源配置注入到ruleManager
FlowRuleManager.register2Property(flowDataSource.getProperty());
degradeDataSource = new CommonDataSource<DegradeRule>(DegradeRuleConverter.create(), RULE_DEGRADE_KEY) {
@Override
public String readSource() {
return rulesConfig.get(RULE_DEGRADE_KEY);
}
};
DegradeRuleManager.register2Property(degradeDataSource.getProperty());
}
}
apollo只需配置相应的和的值即可