CP Subsystem Unsafe Mode

When CP Subsystem is not enabled, that means CPSubsystemConfig.getCPMemberCount() is 0, CP data structures operate in the unsafe mode. In this mode, they use Hazelcast’s partitioning and lazy replication mechanisms instead of CP Subsystem’s consensus mechanism. For more information about the lazy replication mechanism of Hazelcast, see the Consistency and Replication Model chapter.

The unsafe mode provides weaker consistency guarantees compared to when CP Subsystem is enabled. For example, when you increment an IAtomicLong or acquire a FencedLock, just before crash of a member, even though you receive a success response, the write operation (increment of IAtomicLong or acquire of FencedLock) can be lost (which cannot happen when CP Subsystem is enabled). For this reason, the unsafe mode is not recommended for use-cases requiring strong consistency. It is more suitable for development or testing. You should take this limitation into consideration if you use CP Subsystem in production with the unsafe mode.