ZooKeeper by Junqueira, Flavio -- Read -- Imperial Library of Trantor

Index

ZooKeeper Preface

Audience Contents of This Book Conventions Used in this Book Using Code Examples Safari® Books Online How to Contact Us Acknowledgments

I. ZooKeeper Concepts and Basics

1. Introduction

The ZooKeeper Mission

How the World Survived without ZooKeeper What ZooKeeper Doesn’t Do The Apache Project Building Distributed Systems with ZooKeeper

Example: Master-Worker Application

Master Failures Worker Failures Communication Failures Summary of Tasks

Why Is Distributed Coordination Hard? ZooKeeper Is a Success, with Caveats

2. Getting to Grips with ZooKeeper

ZooKeeper Basics

API Overview Different Modes for Znodes

Persistent and ephemeral znodes Sequential znodes

Watches and Notifications Versions

ZooKeeper Architecture

ZooKeeper Quorums Sessions

Getting Started with ZooKeeper

First ZooKeeper Session States and the Lifetime of a Session ZooKeeper with Quorums Implementing a Primitive: Locks with ZooKeeper

Implementation of a Master-Worker Example

The Master Role Workers, Tasks, and Assignments The Worker Role The Client Role

Takeaway Messages

II. Programming with ZooKeeper

3. Getting Started with the ZooKeeper API

Setting the ZooKeeper CLASSPATH Creating a ZooKeeper Session

Implementing a Watcher Running the Watcher Example

Getting Mastership

Getting Mastership Asynchronously Setting Up Metadata

Registering Workers Queuing Tasks The Admin Client Takeaway Messages

4. Dealing with State Change

One-Time Triggers

Wait, Can I Miss Events with One-Time Triggers?

Getting More Concrete: How to Set Watches A Common Pattern The Master-Worker Example

Mastership Changes Master Waits for Changes to the List of Workers Master Waits for New Tasks to Assign Worker Waits for New Task Assignments Client Waits for Task Execution Result

An Alternative Way: Multiop Watches as a Replacement for Explicit Cache Management Ordering Guarantees

Order of Writes Order of Reads Order of Notifications

The Herd Effect and the Scalability of Watches Takeaway Messages

5. Dealing with Failure

Recoverable Failures

The Exists Watch and the Disconnected Event

Unrecoverable Failures Leader Election and External Resources Takeaway Messages

6. ZooKeeper Caveat Emptor

Using ACLs

Built-in Authentication Schemes SASL and Kerberos Adding New Schemes

Session Recovery Version Is Reset When Znode Is Re-Created The sync Call Ordering Guarantees

Order in the Presence of Connection Loss Order with the Synchronous API and Multiple Threads Order When Mixing Synchronous and Asynchronous Calls

Data and Child Limits Embedding the ZooKeeper Server Takeaway Messages

7. The C Client

Setting Up the Development Environment Starting a Session Bootstrapping the Master Taking Leadership Assigning Tasks Single-Threaded versus Multithreaded Clients Takeaway Messages

8. Curator: A High-Level API for ZooKeeper

The Curator Client Fluent API Listeners State Changes in Curator A Couple of Edge Cases Recipes

Leader Latch Leader Selector Children Cache

Takeaway Messages

III. Administering ZooKeeper

9. ZooKeeper Internals

Requests, Transactions, and Identifiers Leader Elections Zab: Broadcasting State Updates Observers The Skeleton of a Server

Standalone Servers Leader Servers Follower and Observer Servers

Local Storage

Logs and Disk Use Snapshots

Servers and Sessions Servers and Watches Clients Serialization Takeaway Messages

10. Running ZooKeeper

Configuring a ZooKeeper Server

Basic Configuration Storage Configuration Network Configuration Cluster Configuration Authentication and Authorization Options Unsafe Options Logging Dedicating Resources

Configuring a ZooKeeper Ensemble

The Majority Rules Configurable Quorums Observers

Reconfiguration

Managing Client Connect Strings

Quotas Multitenancy File System Layout and Formats

Transaction Logs Snapshots Epoch Files Using Stored ZooKeeper Data

Four-Letter Words Monitoring with JMX

Connecting Remotely

Tools Takeaway Messages

Index About the Authors Colophon Copyright

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