注册debug追踪到InstanceRegistry
ApplicationResource #addInstance
registry.register(info, "true".equals(isReplication));------------------>
InstanceRegistry #
@Override
public void register(final InstanceInfo info, final boolean isReplication) {
//springcloud发布一个事件EurekaInstanceRegisteredEvent
handleRegistration(info, resolveInstanceLeaseDuration(info), isReplication);
//调用父类的register
super.register(info, isReplication);
}
---------------------------->>
PeerAwareInstanceRegistryImpl #
/**
* Registers the information about the {@link InstanceInfo} and replicates
* this information to all peer eureka nodes. If this is replication event
* from other replica nodes then it is not replicated.
*
* @param info
* the {@link InstanceInfo} to be registered and replicated.
* @param isReplication
* true if this is a replication event from other replica nodes,
* false otherwise.
*/
@Override
public void register(final InstanceInfo info, final boolean isReplication) {
//服务过期时间默认90秒
int leaseDuration = Lease.DEFAULT_DURATION_IN_SECS;
if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) {
leaseDuration = info.getLeaseInfo().getDurationInSecs();
}
//服务注册
super.register(info, leaseDuration, isReplication);
//集群同步
replicateToPeers(Action.Register, info.getAppName(), info.getId(), info, null, isReplication);
AbstractInstanceRegistry#register 服务注册
我们知道spring容器底层就是一个ConcurrentHashMap,那么eureka的底层注册是什么样的数据结构呢?没错一定也是一个map.
ConcurrentHashMap<String, Map<String, Lease<InstanceInfo>>> registry = new ConcurrentHashMap();
registry的数据结构如上等价于<applicationName, Map<instanceId, Lease>>,为了进行相同服务的集群话,为上一层模块进行调用时方便负载均衡.
/**
* Registers a new instance with a given duration.
*
* @see com.netflix.eureka.lease.LeaseManager#register(java.lang.Object, int, boolean)
*/
public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) {
try {
read.lock();
//根据应用名称获取对应的服务,因为微服务的application name可以相同,
//服务实例instance id是不同的(方便集群,为负载均衡作准备),
Map<String, Lease<InstanceInfo>> gMap = registry.get(registrant.getAppName());
REGISTER.increment(isReplication);
if (gMap == null) {
final ConcurrentHashMap<String, Lease<InstanceInfo>> gNewMap = new ConcurrentHashMap<String, Lease<InstanceInfo>>();
gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap);
if (gMap == null) {
gMap = gNewMap;
}
}
//如果上面存在相同的服务的application name的微服务,那么就根据对应的服务的实例instance id来区分
//尝试通过id拿到一个微服务实例，
Lease<InstanceInfo> existingLease = gMap.get(registrant.getId());
// Retain the last dirty timestamp without overwriting it, if there is already a lease
if (existingLease != null && (existingLease.getHolder() != null)) {
//已经存在的微服务实例最后修改时间
Long existingLastDirtyTimestamp = existingLease.getHolder().getLastDirtyTimestamp();
//要注册的微服务实例最后修改时间
Long registrationLastDirtyTimestamp = registrant.getLastDirtyTimestamp();
logger.debug("Existing lease found (existing={}, provided={}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp);
// this is a > instead of a >= because if the timestamps are equal, we still take the remote transmitted
// InstanceInfo instead of the server local copy.
//如果已存的微服务时间>要注册的（时间越大说明操作越新），用已存的覆盖要注册的
//即如果出现冲突的话拿最新的微服务实例
if (existingLastDirtyTimestamp > registrationLastDirtyTimestamp) {
logger.warn("There is an existing lease and the existing lease's dirty timestamp {} is greater" +
" than the one that is being registered {}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp);
logger.warn("Using the existing instanceInfo instead of the new instanceInfo as the registrant");
registrant = existingLease.getHolder();
}
} else {
// The lease does not exist and hence it is a new registration
synchronized (lock) {
//期待发送心跳的客户端数量
if (this.expectedNumberOfClientsSendingRenews > 0) {
// Since the client wants to register it, increase the number of clients sending renews
//要注册进来了，默认心跳30秒一次,每次心跳在原基础上加一，一分钟2次所以加2
this.expectedNumberOfClientsSendingRenews = this.expectedNumberOfClientsSendingRenews + 1;
updateRenewsPerMinThreshold();
}
}
logger.debug("No previous lease information found; it is new registration");
}
Lease<InstanceInfo> lease = new Lease<InstanceInfo>(registrant, leaseDuration);
if (existingLease != null) {
lease.setServiceUpTimestamp(existingLease.getServiceUpTimestamp());
}
//如果if(gMap == null)都没有进，说明微服务组内已经有微服务了，直接put(id,instance)即可
gMap.put(registrant.getId(), lease);
synchronized (recentRegisteredQueue) {
//最近注册队列添加此微服务
recentRegisteredQueue.add(new Pair<Long, String>(
System.currentTimeMillis(),
registrant.getAppName() + "(" + registrant.getId() + ")"));
}
// This is where the initial state transfer of overridden status happens
if (!InstanceStatus.UNKNOWN.equals(registrant.getOverriddenStatus())) {
logger.debug("Found overridden status {} for instance {}. Checking to see if needs to be add to the "
+ "overrides", registrant.getOverriddenStatus(), registrant.getId());
if (!overriddenInstanceStatusMap.containsKey(registrant.getId())) {
logger.info("Not found overridden id {} and hence adding it", registrant.getId());
overriddenInstanceStatusMap.put(registrant.getId(), registrant.getOverriddenStatus());
}
}
InstanceStatus overriddenStatusFromMap = overriddenInstanceStatusMap.get(registrant.getId());
if (overriddenStatusFromMap != null) {
logger.info("Storing overridden status {} from map", overriddenStatusFromMap);
registrant.setOverriddenStatus(overriddenStatusFromMap);
}
// Set the status based on the overridden status rules
InstanceStatus overriddenInstanceStatus = getOverriddenInstanceStatus(registrant, existingLease, isReplication);
registrant.setStatusWithoutDirty(overriddenInstanceStatus);
// If the lease is registered with UP status, set lease service up timestamp
if (InstanceStatus.UP.equals(registrant.getStatus())) {
lease.serviceUp();
}
//标记微服务实例ADDED
registrant.setActionType(ActionType.ADDED);
//最近改变队列添加此微服务，此队列会保存近三分钟有改动的微服务，用于增量更新
recentlyChangedQueue.add(new RecentlyChangedItem(lease));
//设置最后更新的时间戳
registrant.setLastUpdatedTimestamp();
// 放入缓存中
invalidateCache(registrant.getAppName(), registrant.getVIPAddress(), registrant.getSecureVipAddress());
logger.info("Registered instance {}/{} with status {} (replication={})",
registrant.getAppName(), registrant.getId(), registrant.getStatus(), isReplication);
} finally {
read.unlock();
}
}
updateRenewsPerMinThreshold()
protected void updateRenewsPerMinThreshold() {
this.numberOfRenewsPerMinThreshold = (int) (this.expectedNumberOfClientsSendingRenews
* (60.0 / serverConfig.getExpectedClientRenewalIntervalSeconds())
* serverConfig.getRenewalPercentThreshold());
}
expectedNumberOfClientsSendingRenews:期待发送心跳的客户端数量
ExpectedClientRenewalIntervalSeconds：期待客户端发送心跳的间隔秒数
RenewalPercentThreshold：续期的百分比阈值85%
numberOfRenewsPerMinThreshold：客户端每分钟发送心跳数的阈值，如果server在一分钟内没有收到这么多的心跳数就会触发自我保护机制
举个例子就明白了：
假设有100个客户端，发送心跳间隔为30s，那么一分钟如果全部正常的话server收到的心跳应该是200次，
如果server一分钟收到的心跳<200*85%,即170个触发自我保护机制
/**
* Replicates all eureka actions to peer eureka nodes except for replication
* traffic to this node.
*
*/
private void replicateToPeers(Action action, String appName, String id,
InstanceInfo info /* optional */,
InstanceStatus newStatus /* optional */, boolean isReplication) {
Stopwatch tracer = action.getTimer().start();
try {
// 判断是否是集群同步请求，如果是，则记录最后一分钟的同步次数
if (isReplication) {
numberOfReplicationsLastMin.increment();
}
// If it is a replication already, do not replicate again as this will create a poison replication
// 集群节点为空，或者这是一个Eureka Server 同步请求，直接return
if (peerEurekaNodes == Collections.EMPTY_LIST || isReplication) {
return;
}
// 循环相邻的Eureka Server Node， 分别发起请求同步
for (final PeerEurekaNode node : peerEurekaNodes.getPeerEurekaNodes()) {
// If the url represents this host, do not replicate to yourself.
if (peerEurekaNodes.isThisMyUrl(node.getServiceUrl())) {
continue;
}
// 发起同步请求
replicateInstanceActionsToPeers(action, appName, id, info, newStatus, node);
}
} finally {
tracer.stop();
}
}
集群同步步骤
1.判断集群节点是否为空，为空则返回
2.isReplication 代表是否是一个复制请求， isReplication = true 表示是其他Eureka Server发过来的同步请求
这个时候是不需要继续往下同步的。否则会陷入同步死循环
3.循环集群节点，过滤掉自身的节点
4.发起同步请求 ，调用replicateInstanceActionsToPeers
PS： 这里提到了PeerEurekaNode ， 对于PeerEurekaNodes的集群节点更新及数据读取，在服务启动的时候，对PeerEurekaNodes集群开启了线程更新集群节点信息。每10分钟一次
总结
1：@EnableEurekaServer注入一个Marker类，说明是一个注册中心
2：EurekaServerAutoConfiguration注入一个filter，来拦截jersey请求转发给resource
3：服务注册，就是把信息存到一个ConcurrentHashMap<name, Map<id,Lease>>
4：对于注册冲突拿最新的微服务实例
5：server每分钟内收到的心跳数低于理应收到的85%就会触发自我保护机制
6：Lease的renew bug, duration多加了一次，理应加一个expireTime表示过期时间
7：集群同步：先注册到一台server，然后遍历其他的集群的其他server节点调用register注册到其他server，
isReplication=true代表此次注册来源于集群同步的注册，代表此次注册不要再进行集群同步，避免无限注册
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