Spring的Eureka续约(心跳检测)详解
作者：dalianpai
这篇文章主要介绍了Spring的Eureka续约(心跳检测)详解,eureka client每隔一定的时间,会给eureka server发送心跳,保持心跳,让eureka server知道自己还活着,需要的朋友可以参考下
Eureka 续约 (心跳检测)
心跳，eureka client每隔一定的时间，会给eureka server发送心跳，保持心跳，让eureka server知道自己还活着，lease renewal，续约，心跳.
Eureka-Client 向 Eureka-Server 发起注册应用实例成功后获得租约 ( Lease )。 Eureka-Client 固定间隔向 Eureka-Server 发起续租( renew )，避免租约过期。
默认情况下，租约有效期为 90 秒，续租频率为 30 秒。两者比例为 1 : 3 ，保证在网络异常等情况下，有三次重试的机会。
(1)DiscoveryClient初始化的时候，会去调度一堆定时任务，其中有一个就是HeartbeatThread，心跳线程
(2)在这里可以看到，默认是每隔30秒去发送一次心跳，每隔30秒执行一次HeartbeatTHread线程的逻辑，发送心跳
(3)这边的话就是去发送这个心跳，走的是EurekaHttpClient的sendHeartbeat()方法，//localhost:8080/v2/apps/ServiceA/i-000000-1，走的是put请求
/**
* The heartbeat task that renews the lease in the given intervals.
*/
private class HeartbeatThread implements Runnable {
public void run() {
if (renew()) {
lastSuccessfulHeartbeatTimestamp = System.currentTimeMillis();
}
}
}
/**
* Renew with the eureka service by making the appropriate REST call
*/
boolean renew() {
EurekaHttpResponse<InstanceInfo> httpResponse;
try {
httpResponse = eurekaTransport.registrationClient.sendHeartBeat(instanceInfo.getAppName(), instanceInfo.getId(), instanceInfo, null);
logger.debug(PREFIX + "{} - Heartbeat status: {}", appPathIdentifier, httpResponse.getStatusCode());
if (httpResponse.getStatusCode() == Status.NOT_FOUND.getStatusCode()) {
REREGISTER_COUNTER.increment();
logger.info(PREFIX + "{} - Re-registering apps/{}", appPathIdentifier, instanceInfo.getAppName());
long timestamp = instanceInfo.setIsDirtyWithTime();
boolean success = register();
if (success) {
instanceInfo.unsetIsDirty(timestamp);
}
return success;
}
return httpResponse.getStatusCode() == Status.OK.getStatusCode();
} catch (Throwable e) {
logger.error(PREFIX + "{} - was unable to send heartbeat!", appPathIdentifier, e);
return false;
}
}(4)负责承接服务实例的心跳相关的这些操作的，是ApplicationsResource，服务相关的controller。找到ApplicationResource，再次找到InstanceResource，通过PUT请求，可以找到renewLease方法。
@PUT
public Response renewLease(
@HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication,
@QueryParam("overriddenstatus") String overriddenStatus,
@QueryParam("status") String status,
@QueryParam("lastDirtyTimestamp") String lastDirtyTimestamp) {
boolean isFromReplicaNode = "true".equals(isReplication);
boolean isSuccess = registry.renew(app.getName(), id, isFromReplicaNode);
// Not found in the registry, immediately ask for a register
if (!isSuccess) {
logger.warn("Not Found (Renew): {} - {}", app.getName(), id);
return Response.status(Status.NOT_FOUND).build();
}
// Check if we need to sync based on dirty time stamp, the client
// instance might have changed some value
Response response;
if (lastDirtyTimestamp != null && serverConfig.shouldSyncWhenTimestampDiffers()) {
response = this.validateDirtyTimestamp(Long.valueOf(lastDirtyTimestamp), isFromReplicaNode);
// Store the overridden status since the validation found out the node that replicates wins
if (response.getStatus() == Response.Status.NOT_FOUND.getStatusCode()
&& (overriddenStatus != null)
&& !(InstanceStatus.UNKNOWN.name().equals(overriddenStatus))
&& isFromReplicaNode) {
registry.storeOverriddenStatusIfRequired(app.getAppName(), id, InstanceStatus.valueOf(overriddenStatus));
}
} else {
response = Response.ok().build();
}
logger.debug("Found (Renew): {} - {}; reply status={}", app.getName(), id, response.getStatus());
return response;
}(5)通过注册表的renew()方法，进去完成服务续约，实际进入AbstractInstanceRegistry的renew()方法
/**
* Marks the given instance of the given app name as renewed, and also marks whether it originated from
* replication.
*
* @see com.netflix.eureka.lease.LeaseManager#renew(java.lang.String, java.lang.String, boolean)
*/
public boolean renew(String appName, String id, boolean isReplication) {
RENEW.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> leaseToRenew = null;
if (gMap != null) {
leaseToRenew = gMap.get(id);
}
if (leaseToRenew == null) {
RENEW_NOT_FOUND.increment(isReplication);
logger.warn("DS: Registry: lease doesn't exist, registering resource: {} - {}", appName, id);
return false;
} else {
InstanceInfo instanceInfo = leaseToRenew.getHolder();
if (instanceInfo != null) {
// touchASGCache(instanceInfo.getASGName());
InstanceStatus overriddenInstanceStatus = this.getOverriddenInstanceStatus(
instanceInfo, leaseToRenew, isReplication);
if (overriddenInstanceStatus == InstanceStatus.UNKNOWN) {
logger.info("Instance status UNKNOWN possibly due to deleted override for instance {}"
+ "; re-register required", instanceInfo.getId());
RENEW_NOT_FOUND.increment(isReplication);
return false;
}
if (!instanceInfo.getStatus().equals(overriddenInstanceStatus)) {
logger.info(
"The instance status {} is different from overridden instance status {} for instance {}. "
+ "Hence setting the status to overridden status", instanceInfo.getStatus().name(),
overriddenInstanceStatus.name(),
instanceInfo.getId());
instanceInfo.setStatusWithoutDirty(overriddenInstanceStatus);
}
}
// 新增 续租每分钟次数
renewsLastMin.increment();
// 设置 租约最后更新时间(续租)
leaseToRenew.renew();
return true;
}
}实际的服务续约的逻辑，其实就是在Lease对象中，更新一下lastUpdateTimestamp这个时间戳，每次续约，就更新一下,duration这里加了一遍，也是eureka的bug，但是官网并不做修改。
public void renew() {
lastUpdateTimestamp = System.currentTimeMillis() + duration;
}到此这篇关于Spring的Eureka续约(心跳检测)详解的文章就介绍到这了,更多相关Eureka续约内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！