Hazelcast IMDG 3.8 Released
February 23, 2017
major theme of Hazelcast IMDG 3.8 is better operational experience for
systems requiring maximum uptime. The number of times the cluster must
be shut down for maintenance are dramatically reduced. Advanced data
management capabilities are added for managing persistence and
multi-data center deployments. Hazelcast is being used in more and more
five nines applications where taking maintenance windows is difficult.
Available in 3.8, Rolling Member Upgrades enable users to upgrade
cluster Members without service interruption. This adds to the client
rolling upgrade feature introduced in 3.6 a year ago. Combined with User
Code Deployment this dramatically reduces the need to ever restart a
production Hazelcast cluster.
In Hot Restart Store we add the ability to restart a cluster after a
lights out event with partial failures such as servers that cannot be
restarted. We also allow backed up data to be copied to new machines and
used to restart a new cluster with data intact. Plus we add the ability
to take a snapshot of the Hot Restart Store in a running cluster for
periodic backups that can be saved offline. These features add up to
much higher persistence.
WAN Replication is also enhanced with new Dynamic WAN Synchronization
allowing users to copy one cluster’s data to another without service
interruption. The sync process can be started inside the WAN Sync
interface of Management Center. Therefore, at any time, users can create
a new WAN replication destination and a snapshot of their current
cluster using sync ability. The use case is to allow a new data center
to be brought online without service interruption.
User Code Deployment allows the user code that needs to be deployed to
Hazelcast to allow in-situ processing, for example EntryProcessors, to
be done dynamically from a Member or Lite Member, thus removing the need
to copy jars to each Member and restart.
Hazelcast has a huge community which drive feature development.
Responding to this 3.8 includes numerous enhancements with the
- Fast Aggregations on top of
query execute in a fraction of the time of the old Aggregations
capability. All of the standard aggregations like sum and count
have been built-in. This function has been moved from MapReduce
to more conveniently sit on our Query API. Performance tests
show it 3x faster than competitors.
- Query Projection have also
been added so that specific fields of an entry value rather than
the whole value can be returned. This is very important for
Query performance and cuts the network and serialization
- Scheduled Executor Service, a
feature that enables developers to schedule tasks at any time,
or conduct repetitive scheduling at fixed intervals in a
- Near Cache Preload – Client
Near Caches can be configured to preload entries from the
cluster when the client application starts, so that near caches
are hot before use. Near caches can speed up performance more
- Node.js client improved with
the most frequently used Hazelcast data structures. These
include Distributed Map with support of Predicates and Entry
Processors, MultiMap, Set, List, Distributed Locks and Queue.
- Continuous Query Cache has
been open sourced in 3.8. With this, results of a query are
always ready and local to the application with zero latency.
- HyperLogLog is a new
probabilistic data structure used to “estimate” cardinalities of
unique elements on huge sets. Common use cases include
calculating real time unique site visitor metrics based on IP or
user and measuring campaign performance (impressions, clicks,
etc) in advertising.
- Ring Buffer Store – a storage
mechanism for Ring Buffer, which when enabled allows the reading
of items which are no longer in the Ring Buffer.
- Increase split-brain
protection to cover the Queue and Lock data structures in
addition to the existing Map and Cache. This prevents writes
and/or reads from occurring with sub-clusters which have formed
after a network partition.
Luck, CEO of Hazelcast, said: “There are many important and useful
enhancements in this release which elevates Hazelcast IMDG to a new
level. This couldn’t be done without community support, their
contributions are vital if Hazelcast is to continue to move forward and
offer a solution that is custom-made for specific industry requirements.
Many businesses must now offer services in real time, with the
enhancements and improvements offered in 3.8, Hazelcast users will be
able to build high performance applications safe in the knowledge that
the end user expectation will be met regardless of load.”