CuratorFrameworkFactory有四種重連策略,均實現了RetryPolicy介面.

zk server端timeout引數
tickTime：zk的心跳間隔(heartbeat interval）,也是session timeout基本單位.單位為毫秒.
minSessionTimeout:最小超時時間,zk設定的預設值為2*tickTime.
maxSessionTimeout:最大超時時間,zk設定的預設值為20*tickTime.

客戶端實際的超時時間.

int minSessionTimeout = zk.getMinSessionTimeout();
if (sessionTimeout < minSessionTimeout) {
sessionTimeout = minSessionTimeout;
}
int maxSessionTimeout = zk.getMaxSessionTimeout();
if (sessionTimeout > maxSessionTimeout) {
sessionTimeout = maxSessionTimeout;
}

如果sessionTimeout的設定小於minSessionTimeout,則採用伺服器的minSessionTimeout配置
如果sessionTimeout的設定大於maxSessionTimeout,則採用伺服器的maxSessionTimeout配置.
客戶端的超時設定,不能超過伺服器端配置的範圍

Curator 的客戶端超時設定.
CuratorFrameworkFactory.newClient
連線超時15s
Session超時60s

private static final int DEFAULT_SESSION_TIMEOUT_MS = Integer.getInteger("curator-default-session-timeout", 60 * 1000);
private static final int DEFAULT_CONNECTION_TIMEOUT_MS = Integer.getInteger("curator-default-connection-timeout", 15 * 1000);
public static CuratorFramework newClient(String connectString, RetryPolicy retryPolicy)
{
return newClient(connectString, DEFAULT_SESSION_TIMEOUT_MS, DEFAULT_CONNECTION_TIMEOUT_MS, retryPolicy);
}

Curator 四種重連策略
1.RetryUntilElapsed(int maxElapsedTimeMs, int sleepMsBetweenRetries)
以sleepMsBetweenRetries的間隔重連,直到超過maxElapsedTimeMs的時間設定

2.RetryNTimes(int n, int sleepMsBetweenRetries)
指定重連次數

3.RetryOneTime(int sleepMsBetweenRetry)
重連一次,簡單粗暴

4.ExponentialBackoffRetry
ExponentialBackoffRetry(int baseSleepTimeMs, int maxRetries)
ExponentialBackoffRetry(int baseSleepTimeMs, int maxRetries, int maxSleepMs)

時間間隔 = baseSleepTimeMs * Math.max(1, random.nextInt(1 << (retryCount + 1)))

Curator 重連策略與超時

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