bringing javax.cache'ing to your app

Unless otherwise indicated, these s l ides are © 2013-2015 Pivotal Software, Inc. and l icensed under a Creat ive Commons Attr ibut ion-NonCommercial l icense: ht tp: / /creat ivecommons.org/ l icenses/by-nc/3.0/

SPRINGONE2GXWASHINGTON, DC

Bringing javax.cache’ing to your Application

Chris Dennis, Alex Snaps @tall_chris @alexsnaps


Who are these guys?

• Chris Dennis

• Software Engineer

• Terracotta

• JSR-107 EG member

2

• Alex Snaps • Software Engineer • Terracotta • JCP EC Alternate


Terracotta? Software AG? … Ehcache?! … What the

• Terracotta

• Network Attached Memory

• Distributed Shared Object

• Ehcache

• World’s most used Java caching API

• Joins Terracotta Aug. 2009

• Quartz

• Java’s de facto scheduler

• Join Terracotta Nov. 2009

• Software AG

• Acquires Terracotta May 2011

3


Caching ?

4


Caches are everywhere …

• CPU caches: L1, L2, …

• Network caches

• Browser caches

• Disk caches

• …

5


Why ?

• The closer the better…

• … the faster

• Memory is actually cheap…

• … and getting cheaper

• Use that memory!

6

Unless otherwise indicated, these s l ides are © 2013-2015 Pivotal Software, Inc. and l icensed under a Creat ive Commons Attr ibut ion-NonCommercial l icense: ht tp: / /creat ivecommons.org/ l icenses/by-nc/3.0/ 7


On human scale

8

L1 cache reference 0.5 s One heart beat

L2 cache reference 7 s Long yawn

Main memory reference 100 s Brushing your teeth

Send 2K bytes over 1 Gbps network 5.5 hr From lunch to end of work day

Read 1 MB sequentially from memory 2.9 days A long weekend

Round trip within same datacenter 5.8 days A medium vacation

Read 1 MB sequentially from SSD 11.6 days Delivery in almost 2 weeks!

Disk seek 16.5 weeks A semester in university

Read 1 MB sequentially from disk 7.8 months Almost a baby

Send packet CA->Netherlands->CA 4.8 years Avg time to bachelor's degree


So, a cache is …

• Data structure holding temporary copy of data

• Trades memory usage for reduced latency

• Targets:

• Data which is reused

• Data which is expensive to retrieve / compute

9


JSR-107 aka JCache

10


JSR-107 in a nutshell

• JSR-107 is a Java platform specification

• Java Community Process driven standard

• Specifies API and semantics for temporary, in-memory caching of Java objects, including object creation, shared access, spooling, invalidation, and consistency across JVM's

• Final(ly!) release on 18 Mar, 2014 !

• Comes with

• Standardized API;

• A TCK;

• … a reference implementation.11


What’s in there, you ask?

• CacheManagers managing … Caches !

• Expiry

• Integration

• Cache Entry Listeners

• Entry Processors

• Caching Annotations

• Some Management

• … but no capacity control!

12


Current implementations

• Oracle’s Coherence — $$$

• Terracotta’s Ehcache — OSS & $

• Hazelcast — OSS & $

• JBoss’ Infinispan

• Apache Ignite

• … but also

• Apache JCS

• GemFire

13


JSR-107 is “Store by Value”

• Options:

• Store by Value

• Store by Reference

• What do you really want?

• Store! (by IDGAF)

14


DEMO Caching in PetClinic

15


Hibernate explanation

16


Jpa Entities

• Not any other POJO

• Comes with a lifecycle

• Transient

• Persistent

• Detached

• Removed

• Attached == non thread-safe!

• Associated with a PersistenceContext(i.e. a JDBC Connection!)

• Session flushes at tx.commit() at the latest

• But could be earlier…

17


Hibernate 2nd level cache

• Stores “dehydrated” entities

• i.e. the “column values”, not actual domain objects

• Is maintained through the Hibernate/JPA session

• Where the session acts as the first level cache

• Hibernate supports 4 cache access strategies

• Read-Only

• Read-Write

• Non-Strict Read-Write

• Transactional

18


Hibernate’s Query Cache

• Caches… any query result

• Is responsible for invalidations

• Maintains a per entity “timestamp cache”

• Holds the last time “a table” was modified

• Invalidates cached query results based of TS

• Timestamp cache can become the bottleneck

19


Ehcache 3 aka jsr-107 on steroids

20


Write-behind

• Let’s you scale out writes

• Controls

• Batch sizes

• Temporal aspects of batches being written out

• Concurrency of Queues/Write threads

• Coalescing

• May not be persistent

• Provides “at least once guarantee”

• Simpler in Ehcache 3!

21


Off-heap storage

• JVM process allocated memory

• No GC’ed (i.e. not increasing your GC pauses)

• Does not require sun.misc.Unsafe

• Newly open-sourced!

• No limitations on sizing (tested up to 6TB on a single machine)

• Available as its own library

• Light-weight Java Serialization (default)

• Custom Serialization support (Ehcache3)

• Clock eviction

22


Tiering

23


Ehcache in Spring Demo

24


Beyond M3 aka the future to be defined

25


Milestone 4

• Transaction support, but which?

• As a full XA Resource

• XA Synchronization

• “Local” Transaction

• Automatic Resource Control

• What was in 2.x

• What it could do…

26


Beyond M4

• Clustering using the new Terracotta 5 platform

• All (re) open-sourced

• General purpose clustering platform

• Highly available

• Configurable consistency model

• Resilience

• Pluggable strategy

• Out of the box ones

• no-op

• exceptions

• Plays nicely with cache-through patterns 27

Unless otherwise indicated, these s l ides are © 2013-2015 Pivotal Software, Inc. and l icensed under a Creat ive Commons Attr ibut ion-NonCommercial l icense: ht tp: / /creat ivecommons.org/ l icenses/by-nc/3.0/ 28

Questions ?

@ehcache ehcache.org

Learn More. Stay Connected.

@ehcache ehcache.org

http://ehcache.org

http://ehcache.org

bringing javax.cache'ing to your app

Technology