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Apache Zookeeper

A centralized service for distributed systems that manages configuration, synchronization, and naming through a hierarchical data model

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Configuration Management
Provides one location to store configuration data and update information across nodes
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Service Registry
Keeps a record of service data for discovery and access in a distributed system
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Synchronized Updates
Coordinates state changes so that all clients process operations in the same sequential order
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Barrier Synchronization
Causes processes to wait until all participants reach a synchronization point, coordinating parallel task execution
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Naming Service
Maps names to resources for node identification and communication within the network
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Leader Election
Selects a node to guide further operations, enabling orderly management of distributed tasks
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Quorum Management
Supports agreement among nodes to decide on the system’s state and maintain coordinated operations
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Failure Recovery
Identifies node failures and initiates reconfigurations to maintain operational state
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Failover Support
Monitors for node failures and redirects operations to nodes that remain connected to preserve service continuity
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Atomic Broadcast
Ensures that all nodes receive events in the same sequential order to support state replication
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Hierarchical Data Storage
Organizes data in a tree structure called znodes to aid lookup and data management
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Event Notification
Monitors changes in data and informs clients to support prompt system updates
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Locking Mechanism
Enforces single access to shared resources to avoid conflicting operations
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Ephemeral Nodes
Supports temporary nodes that disappear when a session ends, tracking dynamic state changes
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Watchers
Allows clients to register for notifications when specific nodes experience changes
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Session Management
Tracks client connections and maintains session state through the distributed network
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Scalability Facilitation
Enables addition or removal of nodes while coordinating overall system state
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Data Consistency
Maintains uniform data state across nodes by using a strict ordering protocol in operations
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Data Replication
Duplicates information across nodes to provide redundancy and support operational continuity
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System Monitoring
Offers mechanisms to track the status of nodes and overall system state in real time
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Cluster Coordination
Bridges multiple systems to work on tasks by managing shared state and distributed processing
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API Support
Provides a set of primitives for client applications to integrate coordination features into distributed tasks
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Java Garbage Collection Pauses
Operations may pause during garbage collection cycles in the Java runtime, which can interrupt processes
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Snapshot Operation Stalls
Creating snapshots halts read and write operations, delaying the processing of requests during these period
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Socket Connection Overhead
Opening a new socket per watch request uses system resources and can limit scale if many watches are registered.
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Reconfiguration Risk
Adding new servers to an existing ensemble may lead to state inconsistencies and risk data loss if the new nodes do not maintain the required quorum
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Write Operation Bottleneck
Write requests are handled by the leader node only, which may slow down data processing when many writes occur as write tasks stall until a new leader is elected
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Steep Learning Curve
The underlying concepts of distributed coordination require time and effort to understand and implement correctly
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Scalability Bottleneck for Write
The design allows read operations to scale well but restricts write operations to a single node, which may hinder growth in high-write scenario
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Excessive Network Traffic
Frequent synchronization and state updates among nodes can create high network traffic, impacting throughput
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Challenging Maintenance Tasks
Troubleshooting and maintaining an ensemble demands specialized knowledge, active monitoring and periodic manual configuration changes which can limit independent operation by inexperienced users or delay routine maintenance and system updates
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Risk of Quorum Loss
A drop in the number of available nodes might result in loss of quorum, preventing the system from processing write requests or electing a leader

Platform

Desktop

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System Requirements

#MinimumRecommended
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  • GNU/Linux
  • Solaris
  • FreeBSD
  • Windows
  • Mac OS X
GNU/Linux
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Dual core processors
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2 GB RAM
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80 GB IDE hard drives
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Java, release 1.8 or greater - JDK 8 LTS, JDK 11 LTS, JDK 12 (Java 9 and 10 are not supported).
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Recommended hardware requirements aren’t requirements per se but what’s known to work. See source for more information.

Ratings

4.65
5

ACTE
5.0
5
based on 19675 reviews
G2CROWD
4.3
5
based on 99 reviews

Developer

Written in

Java, C++, C

Initial Release

27 October 2008

Repository

License

Categories

Alternatives

Distributed Co-ordination Service
No alternative software available under 'Distributed Co-ordination Service' category.

Notes

A notable thied-party guide on getting started with Apache Zookeeper on Ubuntu - here