...

A good case is to detect GC time locally (from another JVM or native codei.e. using JVMTI agent) and kill the node in case of exceeding.

...

Zookeeper or similar coordinator should be used.

Current implementation of ZookeeperDiscoverySpi should be rewritten, because

Zookeeper and similar coordinators (i.e. etcd) are not intended to store large amount of data.

TCP transport for delivering messages should be implemented and leave Zookeeper only coordination, 

service discovery and similar tasks.

Risks and Assumptions

// Describe project risks, such as API or binary compatibility issues, major protocol changes, etc.

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