channel watcher maybe closed by etcd client, which may lead to a dead loop and cpu usage increase 100%. add rewatch and backoff mechanism to avoid it
channel watcher maybe closed by etcd client, which may lead to a dead loop and cpu usage increase 100%. add rewatch and backoff mechanism to avoid it

Signed-off-by: xhh1989 <c24c5f895c4c3824725dfb40d86056232bad30cb@gmail.com>

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