diff --git a/database/mysql/README.md b/database/mysql/README.md
index 38dc441..8041547 100644
--- a/database/mysql/README.md
+++ b/database/mysql/README.md
@@ -494,13 +494,7 @@
   - 建议大家主键一定是自增的，别用UUID之类的，因为主键自增，那么起码你的聚簇索引不会频繁的分裂，主键值都是有序的，就会自然的新增一个页而已，但是如果你用的是UUID，那
     么也会导致聚簇索引频繁的页分裂
 
-
-
-
-
-
-
-
+### 109-111: 案例实战：千万级用户场景下的运营系统SQL调优
 
 
 
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/NetflixHystrix.md b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/NetflixHystrix.md
index eae75f6..ff18d86 100644
--- a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/NetflixHystrix.md
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/NetflixHystrix.md
@@ -24,7 +24,7 @@
 
 
 ### 使用编程方式实现服务的容错、降级
-
+- [NacosClientHystrixCommand.java] - [NacosClientHystrixObservableCommand.java]
 
 ### 编程方式开启 Hystrix 请求缓存
 
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/pom.xml b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/pom.xml
index 4cb3698..3c5d3cb 100644
--- a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/pom.xml
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/pom.xml
@@ -35,10 +35,20 @@
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
         </dependency>
+        <!-- 工具方法 -->
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>fastjson</artifactId>
+            <version>1.2.51</version>
+        </dependency>
     </dependencies>
 
     <!--
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/HystrixApplication.java b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/HystrixApplication.java
index 81cc008..131df62 100644
--- a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/HystrixApplication.java
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/HystrixApplication.java
@@ -2,6 +2,7 @@ package org.example;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.web.servlet.ServletComponentScan;
 import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
 import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
 import org.springframework.cloud.context.config.annotation.RefreshScope;
@@ -10,6 +11,7 @@ import org.springframework.cloud.context.config.annotation.RefreshScope;
 @EnableDiscoveryClient
 @RefreshScope // 刷新配置
 @EnableCircuitBreaker // 启动 Hystrix
+@ServletComponentScan // 扫描过滤器
 public class HystrixApplication {
     public static void main(String[] args) {
         SpringApplication.run(HystrixApplication.class, args);
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/controller/HystrixController.java b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/controller/HystrixController.java
index 5203ec1..9f70d11 100644
--- a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/controller/HystrixController.java
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/controller/HystrixController.java
@@ -1,15 +1,24 @@
 package org.example.controller;
 
+import com.alibaba.fastjson.JSON;
 import lombok.extern.slf4j.Slf4j;
+import org.example.hystrix.NacosClientHystrixCommand;
+import org.example.hystrix.NacosClientHystrixObservableCommand;
 import org.example.hystrix.UseHystrixCommandAnnotation;
+import org.example.service.NacosClientService4HystrixDemo;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
+import rx.Observable;
+import rx.Observer;
 
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.Future;
 
 /**
  * <h1>Hystrix Controller</h1>
@@ -21,8 +30,11 @@ public class HystrixController {
 
     private final UseHystrixCommandAnnotation hystrixCommandAnnotation;
 
-    public HystrixController(UseHystrixCommandAnnotation useHystrixCommandAnnotation) {
+    private final NacosClientService4HystrixDemo nacosClientService4HystrixDemo;
+
+    public HystrixController(UseHystrixCommandAnnotation useHystrixCommandAnnotation, NacosClientService4HystrixDemo nacosClientService4HystrixDemo) {
         this.hystrixCommandAnnotation = useHystrixCommandAnnotation;
+        this.nacosClientService4HystrixDemo = nacosClientService4HystrixDemo;
     }
 
     /**
@@ -35,4 +47,86 @@ public class HystrixController {
                 serviceId, Thread.currentThread().getName());
         return hystrixCommandAnnotation.getNacosClientInfo(serviceId);
     }
+
+    @GetMapping("/simple-hystrix-command")
+    public List<ServiceInstance> getServiceInstanceByServiceId(
+            @RequestParam String serviceId) throws Exception {
+
+        // 第一种方式 - 耗时不长的场景使用
+        List<ServiceInstance> serviceInstances01 = new NacosClientHystrixCommand(
+                nacosClientService4HystrixDemo, serviceId
+        ).execute();    // 同步阻塞 -> (创建一个新的线程来进行执行这个策略)
+        log.info("use execute to get service instances: [{}], [{}]",
+                JSON.toJSONString(serviceInstances01), Thread.currentThread().getName());
+
+        // 第二种方式 - 最常见的方式
+        List<ServiceInstance> serviceInstances02;
+        Future<List<ServiceInstance>> future = new NacosClientHystrixCommand(
+                nacosClientService4HystrixDemo, serviceId
+        ).queue();      // 异步非阻塞, 但是已经调用
+        // 这里可以做一些别的事, 需要的时候再去拿结果
+        serviceInstances02 = future.get();
+        log.info("use queue to get service instances: [{}], [{}]",
+                JSON.toJSONString(serviceInstances02), Thread.currentThread().getName());
+
+        // 第三种方式
+        Observable<List<ServiceInstance>> observable = new NacosClientHystrixCommand(
+                nacosClientService4HystrixDemo, serviceId
+        ).observe();        // 热响应调用, 直到下面 toBlocking().single() 的时候才开始调用, 但是已经启用了线程
+        List<ServiceInstance> serviceInstances03 = observable.toBlocking().single();
+        log.info("use observe to get service instances: [{}], [{}]",
+                JSON.toJSONString(serviceInstances03), Thread.currentThread().getName());
+
+        // 第四种方式
+        Observable<List<ServiceInstance>> toObservable = new NacosClientHystrixCommand(
+                nacosClientService4HystrixDemo, serviceId
+        ).toObservable();        // 异步冷响应调用, 未调用, 也未启动线程
+        List<ServiceInstance> serviceInstances04 = toObservable.toBlocking().single();
+        log.info("use toObservable to get service instances: [{}], [{}]",
+                JSON.toJSONString(serviceInstances04), Thread.currentThread().getName());
+
+        // execute = queue + get
+        return serviceInstances01; // 随便返回一个结果, 3,4 不需要返回结果
+    }
+
+    @GetMapping("/hystrix-observable-command")
+    public List<ServiceInstance> getServiceInstancesByServiceIdObservable(
+            @RequestParam String serviceId) {
+
+        List<String> serviceIds = Arrays.asList(serviceId, serviceId, serviceId);
+        List<List<ServiceInstance>> result = new ArrayList<>(serviceIds.size());
+
+        NacosClientHystrixObservableCommand observableCommand =
+                new NacosClientHystrixObservableCommand(nacosClientService4HystrixDemo, serviceIds);
+
+        // 异步执行命令
+        Observable<List<ServiceInstance>> observe = observableCommand.observe();
+
+        // 注册获取结果
+        observe.subscribe(
+                new Observer<List<ServiceInstance>>() {
+
+                    // 执行 onNext 之后再去执行 onCompleted
+                    @Override
+                    public void onCompleted() {
+                        log.info("all tasks is complete: [{}], [{}]",
+                                serviceId, Thread.currentThread().getName());
+                    }
+
+                    @Override
+                    public void onError(Throwable e) {
+                        e.printStackTrace();
+                    }
+
+                    @Override
+                    public void onNext(List<ServiceInstance> instances) {
+                        result.add(instances);
+                    }
+                }
+        );
+
+        log.info("observable command result is : [{}], [{}]",
+                JSON.toJSONString(result), Thread.currentThread().getName());
+        return result.get(0); // 取一个返回
+    }
 }
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/filter/HystrixRequestContextServletFilter.java b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/filter/HystrixRequestContextServletFilter.java
new file mode 100644
index 0000000..e445959
--- /dev/null
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/filter/HystrixRequestContextServletFilter.java
@@ -0,0 +1,90 @@
+package org.example.filter;
+
+import com.netflix.hystrix.strategy.HystrixPlugins;
+import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
+import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategyDefault;
+import com.netflix.hystrix.strategy.concurrency.HystrixRequestContext;
+import com.netflix.hystrix.strategy.eventnotifier.HystrixEventNotifier;
+import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;
+import com.netflix.hystrix.strategy.metrics.HystrixMetricsPublisher;
+import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+
+import javax.servlet.*;
+import javax.servlet.annotation.WebFilter;
+import java.io.IOException;
+
+/**
+ * <h1>初始化 Hystrix 请求上下文环境</h1>
+ * */
+@Slf4j
+@Component
+@WebFilter(
+        filterName = "HystrixRequestContextServletFilter",
+        urlPatterns = "/*", // 所有的 URL 都经过该请求
+        asyncSupported = true // 异步的请求调用也是支持的
+)
+public class HystrixRequestContextServletFilter implements Filter {
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response,
+                         FilterChain chain) throws IOException, ServletException {
+
+        // 初始化 Hystrix 请求上下文
+        // 在不同的 context 中缓存是不共享的
+        // 这个初始化是必须的
+        HystrixRequestContext context = HystrixRequestContext.initializeContext();
+
+        try {
+            // 配置
+            hystrixConcurrencyStrategyConfig();
+            // 请求正常通过
+            chain.doFilter(request, response);
+        } finally {
+            // 关闭 Hystrix 请求上下文
+            context.shutdown();
+        }
+    }
+
+    /**
+     * <h2>配置 Hystrix 的并发策略</h2>
+     * */
+    public void hystrixConcurrencyStrategyConfig() {
+
+        try {
+
+            HystrixConcurrencyStrategy target =
+                    HystrixConcurrencyStrategyDefault.getInstance();
+            HystrixConcurrencyStrategy strategy =
+                    HystrixPlugins.getInstance().getConcurrencyStrategy();
+            if (strategy instanceof HystrixConcurrencyStrategyDefault) {
+                // 如果已经就是我们想要配置的
+                return;
+            }
+
+            // 将原来其他的配置保存下来
+            HystrixCommandExecutionHook commandExecutionHook =
+                    HystrixPlugins.getInstance().getCommandExecutionHook();
+            HystrixEventNotifier eventNotifier =
+                    HystrixPlugins.getInstance().getEventNotifier();
+            HystrixMetricsPublisher metricsPublisher =
+                    HystrixPlugins.getInstance().getMetricsPublisher();
+            HystrixPropertiesStrategy propertiesStrategy =
+                    HystrixPlugins.getInstance().getPropertiesStrategy();
+
+            // 先重置, 再把我们自定义的配置与原来的配置写回去
+            HystrixPlugins.reset();
+            HystrixPlugins.getInstance().registerConcurrencyStrategy(target);
+            HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);
+            HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);
+            HystrixPlugins.getInstance().registerMetricsPublisher(metricsPublisher);
+            HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);
+
+            log.info("config hystrix concurrency strategy success");
+        } catch (Exception ex) {
+            log.error("Failed to register Hystrix Concurrency Strategy: [{}]",
+                    ex.getMessage(), ex);
+        }
+    }
+}
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/hystrix/NacosClientHystrixCommand.java b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/hystrix/NacosClientHystrixCommand.java
new file mode 100644
index 0000000..d7b55fe
--- /dev/null
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/hystrix/NacosClientHystrixCommand.java
@@ -0,0 +1,83 @@
+package org.example.hystrix;
+
+import com.netflix.hystrix.*;
+import lombok.extern.slf4j.Slf4j;
+import org.example.service.NacosClientService4HystrixDemo;
+import org.springframework.cloud.client.ServiceInstance;
+
+import java.util.Collections;
+import java.util.List;
+
+import static com.netflix.hystrix.HystrixCommandProperties.ExecutionIsolationStrategy.THREAD;
+
+/**
+ * <h1>给 NacosClientService 实现包装</h1>
+ * Hystrix 舱壁模式:
+ *  1. 线程池
+ *  2. 信号量: 算法 + 数据结构, 有限状态机 (伪线程隔离, 只是用代码的方式进行操作, 看似线程隔离, 不常用, 资源实际未被隔离)
+ * */
+@Slf4j
+public class NacosClientHystrixCommand extends HystrixCommand<List<ServiceInstance>> {
+
+    /** 需要保护的服务 */
+    private final NacosClientService4HystrixDemo nacosClientService;
+
+    /** 方法需要传递的参数 */
+    private final String serviceId;
+
+    public NacosClientHystrixCommand(NacosClientService4HystrixDemo nacosClientService, String serviceId) {
+
+        // 线程隔离
+        super(
+                Setter.withGroupKey(
+                                HystrixCommandGroupKey.Factory.asKey("NacosClientService4HystrixDemo"))
+                        .andCommandKey(HystrixCommandKey.Factory.asKey("NacosClientHystrixCommand"))
+                        .andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey("NacosClientPool"))
+                        // 线程池 key 配置
+                        .andCommandPropertiesDefaults(
+                                HystrixCommandProperties.Setter()
+                                        .withExecutionIsolationStrategy(THREAD) // 线程池隔离策略
+                                        .withFallbackEnabled(true)  // 开启降级
+                                        .withCircuitBreakerEnabled(true)    // 开启熔断器
+                        )
+        );
+
+        // 可以配置信号量隔离策略
+//        Setter semaphore =
+//                Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("NacosClientService4HystrixDemo"))
+//                .andCommandKey(HystrixCommandKey.Factory.asKey("NacosClientHystrixCommand"))
+//                .andCommandPropertiesDefaults(
+//                        HystrixCommandProperties.Setter()
+//                        .withCircuitBreakerRequestVolumeThreshold(10) // 至少有10个请求开始, 熔断器才开始熔断计算
+//                        .withCircuitBreakerSleepWindowInMilliseconds(5000) // 熔断器的请求 5s 后会进入一个半打开的状态, 放开部分请求会进行一个重试
+//                        .withCircuitBreakerErrorThresholdPercentage(50) // 当错误率到 50% 就开启熔断保护
+//                        .withExecutionIsolationStrategy(SEMAPHORE)  // 指定使用信号量隔离
+//                        //..... 可以参考上面的线程隔离策略的配置
+//                );
+
+        this.nacosClientService = nacosClientService;
+        this.serviceId = serviceId;
+    }
+
+    /**
+     * <h2>要保护的方法调用写在 run 方法中</h2>
+     * */
+    @Override
+    protected List<ServiceInstance> run() throws Exception {
+        // 保护逻辑
+        log.info("NacosClientService4HystrixDemo In Hystrix Command to Get Service Instance: [{}], [{}]",
+                this.serviceId, Thread.currentThread().getName());
+        return this.nacosClientService.getNacosClientInfo(this.serviceId);
+    }
+
+    /**
+     * <h2>降级处理策略</h2>
+     * */
+    @Override
+    protected List<ServiceInstance> getFallback() {
+
+        log.warn("NacosClientService4HystrixDemo run error: [{}], [{}]",
+                this.serviceId, Thread.currentThread().getName());
+        return Collections.emptyList();
+    }
+}
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/hystrix/NacosClientHystrixObservableCommand.java b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/hystrix/NacosClientHystrixObservableCommand.java
new file mode 100644
index 0000000..cf72493
--- /dev/null
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/hystrix/NacosClientHystrixObservableCommand.java
@@ -0,0 +1,101 @@
+package org.example.hystrix;
+
+
+import com.alibaba.fastjson.JSON;
+import com.netflix.hystrix.HystrixCommandGroupKey;
+import com.netflix.hystrix.HystrixCommandKey;
+import com.netflix.hystrix.HystrixCommandProperties;
+import com.netflix.hystrix.HystrixObservableCommand;
+import lombok.extern.slf4j.Slf4j;
+import org.example.service.NacosClientService4HystrixDemo;
+import org.springframework.cloud.client.ServiceInstance;
+import rx.Observable;
+import rx.Subscriber;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * <h1>HystrixCommand, 隔离策略是基于信号量实现的</h1>
+ * */
+@Slf4j
+public class NacosClientHystrixObservableCommand extends HystrixObservableCommand<List<ServiceInstance>> {
+    /** 要保护的服务 */
+    private final NacosClientService4HystrixDemo nacosClientService4HystrixDemo;
+
+    /** 方法需要传递的参数 */
+    private final List<String> serviceIds;
+
+    public NacosClientHystrixObservableCommand(NacosClientService4HystrixDemo nacosClientService4HystrixDemo,
+                                               List<String> serviceIds) {
+        super(
+                HystrixObservableCommand.Setter
+                        .withGroupKey(HystrixCommandGroupKey
+                                .Factory.asKey("NacosClientService4HystrixDemo"))
+                        .andCommandKey(HystrixCommandKey
+                                .Factory.asKey("NacosClientHystrixObservableCommand"))
+                        .andCommandPropertiesDefaults(
+                                HystrixCommandProperties.Setter()
+                                        .withFallbackEnabled(true)          // 开启降级
+                                        .withCircuitBreakerEnabled(true)    // 开启熔断器
+                        )
+        );
+
+        this.nacosClientService4HystrixDemo = nacosClientService4HystrixDemo;
+        this.serviceIds = serviceIds;
+    }
+
+    /**
+     * <h2>要保护的方法调用写在这里</h2>
+     * */
+    @Override
+    protected Observable<List<ServiceInstance>> construct() {
+
+        // Observable 有三个关键的事件方法, 分别是 onNext、onCompleted、onError
+        return Observable.unsafeCreate(subscriber -> {
+
+            try {
+                if (!subscriber.isUnsubscribed()) {
+                    log.info("subscriber command task: [{}], [{}]",
+                            JSON.toJSONString(serviceIds),
+                            Thread.currentThread().getName());
+                    serviceIds.forEach(
+                            s -> subscriber
+                                    .onNext(nacosClientService4HystrixDemo.getNacosClientInfo(s))
+                    );
+                    subscriber.onCompleted();
+                    log.info("command task completed: [{}], [{}]",
+                            JSON.toJSONString(serviceIds),
+                            Thread.currentThread().getName());
+                }
+            } catch (Exception ex) {
+                subscriber.onError(ex);
+            }
+        });
+    }
+
+    /**
+     * <h2>服务降级</h2>
+     * */
+    @Override
+    protected Observable<List<ServiceInstance>> resumeWithFallback() {
+
+        return Observable.unsafeCreate(subscriber -> {
+
+            try {
+                if (!subscriber.isUnsubscribed()) {
+                    log.info("(fallback) subscriber command task: [{}], [{}]",
+                            JSON.toJSONString(serviceIds),
+                            Thread.currentThread().getName());
+                    subscriber.onNext(Collections.emptyList());
+                    subscriber.onCompleted();
+                    log.info("(fallback) command task completed: [{}], [{}]",
+                            JSON.toJSONString(serviceIds),
+                            Thread.currentThread().getName());
+                }
+            } catch (Exception ex) {
+                subscriber.onError(ex);
+            }
+        });
+    }
+}
diff --git a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/service/NacosClientService4HystrixDemo.java b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/service/NacosClientService4HystrixDemo.java
index 4b403d0..7a58ef7 100644
--- a/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/service/NacosClientService4HystrixDemo.java
+++ b/dev-protocol-springcloud/dev-protocol-springcloud-hystrix/src/main/java/org/example/service/NacosClientService4HystrixDemo.java
@@ -22,12 +22,12 @@ public class NacosClientService4HystrixDemo {
      * */
     public List<ServiceInstance> getNacosClientInfo(String serviceId) {
 
-        // 测试 UseHystrixCommandAnnotation 的超时
-        try {
-            Thread.sleep(2000);
-        } catch (InterruptedException ex) {
-
-        }
+        // 1. 测试 UseHystrixCommandAnnotation 的超时
+//        try {
+//            Thread.sleep(2000);
+//        } catch (InterruptedException ex) {
+//
+//        }
 
 //        测试 NacosClientHystrixCommand 熔断
 //        throw new RuntimeException("has some error");