Spring Cloud config之三：config-server由於server端和client端的健康檢查致使服務超時阻塞問題

springcloud線上一個問題，當config-server連不上git時，微服務集羣慢慢的都掛掉。

在入口層增長了日誌跟蹤問題：

org.springframework.cloud.config.server.environment.EnvironmentController.java

    @RequestMapping("/{name}/{profiles}/{label:.*}")
    public Environment labelled(@PathVariable String name, @PathVariable String profiles,
            @PathVariable String label) {
        if (name != null && name.contains("(_)")) {
            // "(_)" is uncommon in a git repo name, but "/" cannot be matched
            // by Spring MVC
            name = name.replace("(_)", "/");
        }
        if (label != null && label.contains("(_)")) {
            // "(_)" is uncommon in a git branch name, but "/" cannot be matched
            // by Spring MVC
            label = label.replace("(_)", "/");
        }
        StopWatch sw = new StopWatch("labelled");
        sw.start();
        logger.info("EnvironmentController.labelled()開始,name={},profiles={},label={}", name, profiles, label);
        Environment environment = this.repository.findOne(name, profiles, label);
        sw.stop();
        logger.info("EnvironmentController.labelled()結束,name={},profiles={},label={},耗時={}毫秒,耗時={}秒", name, profiles, label, sw.getTotalTimeMillis(), sw.getTotalTimeSeconds());
        return environment;
    }

健康檢查的入口ConfigServerHealthIndicator.java增長日誌：

@Override
    protected void doHealthCheck(Health.Builder builder) throws Exception {
        StopWatch sw = new StopWatch("doHealthCheck");
        sw.start();
        logger.info("ConfigServerHealthIndicator.doHealthCheck()開始,builder={}", builder);
        builder.up();
        List<Map<String, Object>> details = new ArrayList<>();
        for (String name : this.repositories.keySet()) {
            Repository repository = this.repositories.get(name);
            String application = (repository.getName() == null)? name : repository.getName();
            String profiles = repository.getProfiles();

            try {
                Environment environment = this.environmentRepository.findOne(application, profiles, repository.getLabel());

                HashMap<String, Object> detail = new HashMap<>();
                detail.put("name", environment.getName());
                detail.put("label", environment.getLabel());
                if (environment.getProfiles() != null && environment.getProfiles().length > 0) {
                    detail.put("profiles", Arrays.asList(environment.getProfiles()));
                }

                if (!CollectionUtils.isEmpty(environment.getPropertySources())) {
                    List<String> sources = new ArrayList<>();
                    for (PropertySource source : environment.getPropertySources()) {
                        sources.add(source.getName());
                    }
                    detail.put("sources", sources);
                }
                details.add(detail);
            } catch (Exception e) {
                HashMap<String, String> map = new HashMap<>();
                map.put("application", application);
                map.put("profiles", profiles);
                builder.withDetail("repository", map);
                builder.down(e);
                return;
            }
        }
        builder.withDetail("repositories", details);
        sw.stop();
        logger.info("ConfigServerHealthIndicator.doHealthCheck()結束,耗時={}毫秒,耗時={}秒,builder={}", sw.getTotalTimeMillis(), sw.getTotalTimeSeconds(), builder);
    }

經過耗時統計的日誌分析後，發現是EnvironmentController和ConfigServerHealthIndicator調用次數太多，這兩個調用最終會調用JGitEnvironmentRepository.fetch()方法，這個fetch方法會去請求git，超時時間大概是5秒。

因爲請求的數量過多，服務請求不過來，線程阻塞了很長時間。

分析：

一、EnvironmentController的調用是每一個微服務模塊發起的，爲何？

二、ConfigServerHealthIndicator的調用是config-server的健康檢查，能夠經過設置檢查的間隔時間緩解問題。

    consul:
      host: 10.200.110.100
      port: 8500
      enabled: true
      discovery:
        enabled: true
        hostname: 10.200.110.100 healthCheckInterval: 30s
        queryPassing: true

 

EnvironmentController的請求時用config-server的client端的健康檢查發起的調用。看源碼：

各個客戶端在鏈接註冊中心，獲取到配置中心實例後，會調用上面這段代碼邏輯從配置中心獲取到 Environment數據變量，上線環境後，遇到了一個問題，查看日誌，發現這塊邏輯被不停的調用，每20多秒就會調用一次，application的name爲 app,經過查看SpringCloudConfig的官方文檔知道Config Server 經過一個健康指示器來檢測配置的EnvironmentRepository是否正常工做。 默認狀況下會向EnvironmentRepository詢問一個名字爲app的應用配置，EnvironmentRepository實例迴應default配置。   也就是說當健康監視器默認開啓的時候，會不停的調用findOne來檢測，配置是否可用，是否會出現異常，

這段代碼是org.springframework.cloud.config.server.config.ConfigServerHealthIndicator類裏初始化名稱爲application名字爲app的代碼

@ConfigurationProperties("spring.cloud.config.server.health")
public class ConfigServerHealthIndicator extends AbstractHealthIndicator {

    private EnvironmentRepository environmentRepository;

    private Map<String, Repository> repositories = new LinkedHashMap<>();

    public ConfigServerHealthIndicator(EnvironmentRepository environmentRepository) {
        this.environmentRepository = environmentRepository;
    }

    @PostConstruct
    public void init() {
        if (this.repositories.isEmpty()) {
            this.repositories.put("app", new Repository());
        }
    }
       //...
}

若是想中止掉這樣的檢測能夠經過配置health.config.enabled=false去關閉此功能。

看源碼：org.springframework.cloud.config.client.ConfigClientAutoConfiguration.java

@Configuration
public class ConfigClientAutoConfiguration {
    @Configuration
    @ConditionalOnClass(HealthIndicator.class)
    @ConditionalOnBean(ConfigServicePropertySourceLocator.class)
    @ConditionalOnProperty(value = "health.config.enabled", matchIfMissing = true)
    protected static class ConfigServerHealthIndicatorConfiguration {

        @Bean
        public ConfigServerHealthIndicator configServerHealthIndicator(
                ConfigServicePropertySourceLocator locator,
                ConfigClientHealthProperties properties, Environment environment) {
            return new ConfigServerHealthIndicator(locator, environment, properties);
        }
    }
//...