Caching and JCache with Greg Luck 18.02.16

© 2016 Hazelcast Inc. Confidential & Proprietary ‹#›
GREG LUCK, CO-SPEC LEAD JSR107
@GREGRLUCK CEO | HAZELCAST FOUNDER | EHCACHE FORMER CTO
18 FEBRUARY 2016
How to speed up your
application using JCache

Agenda
• Theory of Caching
• Java Caching (JCache), JSR-107
• Code Demo

Introduction to Caching

Benefits of Caching
• Performance
• Offload expensive or non-scalable parts of your architecture
• Scale up – get the most out of one machine
• Scale out – add more capacity with more machines
• Excellent Buffer against load variability
And…
• Usually very fast and easy to apply

When to Use Caching
• When applications use the same data more than once
• When cost (time / resources) of making an initial copy is less
than fetching or producing the data again or when faster to
request from a Cache

Common Problem Areas that Benefit
Anything Web Scale Anything where the data is across the network
Compound Data Objects Data Persistence
1 3
2 4

Database Caching
Moving data from the database into the cache increases processing speed  
and can reduce database licensing and maintenance costs.
Speed ✓
Data  
Store
Application
Cache
Application
Cache
Application
Cache
Application
Cache
Costs ✓ Scalability ✓
~200 us
Average Response Time

Caches are built primarily in RAM 
in-process or distributed
Flash/SSD 
(serialized form)
Local Storage
Heap 
(Objects)
Opaque to  
GC in RAM 
(serialized form)
<100 ns
< 100ns 
+deserialization time
2
500
1,000+
Latency
Size (GB)
Network Storage
< 50us 
< 140us for 1Gbps 
< 70us for 10Gbps/40Gbps 
20,000+Scaleout across the network 
(serialized form)

‘s law
Estimated Performance Improvements
Predicted System Speedup
=
1 / ((1 – Proportion Sped Up) + Proportion Sped Up / Speed up))

Cache Efficiency
Cache Efficiency = cache hits / total hits
• High efficiency = high offload
• High efficiency = high performance
• How to increase:
- Put reference data in the cache
- Put long lived in the cache.
- Consider frequency of mutability of data
- Put highly used data in cache
- Increase the size of the cache. Today you can create TB sized caches

Problems to Consider
• Standalone Caches and the N * problem
- As each entry expires, the backing system gets N requests for data where
n is the number of standalone caches. Solution: Use a distributed cache
• Consistency with the System of Record
- How to keep the cache in sync with changes in a backing system. Solution:
Match mutability of data with data safety configuration. Update the cache
and backing store at the same time.
• Consistency with other cache nodes
- How to keep all cache nodes in sync: Solution: Use a distributed cache and
match consistency configuration with data mutability

New JCache Standard (JSR107)

Java Caching (JCache)
What?
• Java Caching (JCache) standardized Caching for the Java Platform*
• A common mechanism to create, access, update and remove
information from Caches
How?
• JSR-107: Java Caching Specification (JCache)
• Java Community Process (JCP) 2.9

Why?
• Standardize! Standardize! Standardize!
- Core Caching Concepts
- Core Caching API 
• Provide application portability between Caching solutions
- Big & Small, Open & Commercial 
• Caching is ubiquitous! 
• Allows frameworks to depend on JCache and stop creating specific
integrations to each and every cache

Java Caching (Jcache)
Recent History
Item Date
JCache Final Spec Released 18 March 2014
Spring 4.1 September 2014
Hazelcast 3.3.1 TCK Compliant September 2014
Hazelcast 3.4 (with High-Density Memory Store) November 2014
Hazelcast 3.5 - added HD Memory Store to near cache) June 2015
Most project vendors create implementations June 2014 - June 2015
Hazelcast 3.6 (split brain handler, quorums) January 2016
JCache 1.1 Maintenance Release March 2016
Herenow!

Which Platform?
java.util.Map (Java 6/7) Target Platform
Specification (SPEC) Java 6+ (SE or EE)
Reference Implementation (RI) Java 7+ (SE or EE)
Technology Compatibility Kit (TCK) Java 7+ (SE or EE)
Demos and Samples Java 7+ (SE or EE)

Implementations
Implementations
• JCache Reference Implementation
• Ehcache
• Hazelcast
• Oracle Coherence
• Infinispan
• GridGain/Apache Ignite
• TayzGrid*
• Caffeine* (Ben Manes)
Keep Track
• https://jcp.org/aboutJava/communityprocess/implementations/jsr107/index.html
• * Being verified by spec leads

Non-Implementation: Gemfire/Geode
Gemfire/Geode have no plans to implement
Why?
• Gemfire and Geode are directly supported in Spring
• Because Spring supports JCache cache annotations you can use
Gemfire/Geode from Spring but that is it.
See:
• http://apache-geode-incubating-developers-forum.70738.x6.nabble.com/
JCache-JSR-107-support-td1255.html
Campaign to have Pivotal Support JCache:
#PivotalJCache campaign for @PivotalGemFire to support #JSR107 #JCache.
Please retweet or mention #PivotalJCache

Relationship to NoSQL
Difficult/Impossible for NoSQL to fully implement the spec
• Server Side code execution including: Entry Processors, Listeners,
Write-Through etc.
• Strong Consistency is the default consistency model and is not
supported by most/all NoSQL.
Likely that Couchbase will release a partial implementation  
leaving out EntryProcessor and some other methods with an
UnsupportedOperationException if these methods are called. They
have Developer Preview 2 out.
Using With NoSQL
• Use NoSQL like a database and read-through/write-though to it using
CacheLoader/CacheWriter.
• NoSQL gives you scale our persistence - cache gives you very low
latencies

Project Hosting
• JCP Project:
- http://jcp.org/en/jsr/detail?id=107 
• Source Code:
- https://github.com/jsr107 
• Forum:
- https://groups.google.com/forum/?fromgroups#!forum/jsr107

How to get it
• Apache Maven (via Maven Central Repository)
<dependency>
<groupId>javax.cache</groupId>
<artifactId>cache-api</artifactId>
<version>1.0</version>
</dependency>

Caches and Caching

Caches and Caching
JSR107 Cache Definition:
A high-performance, low-latency data-structure* in
which an application places a temporary copy of
information that is likely to be used more than once

Maps vs Cache APIs
java.util.Map (Java 6/7)
Key-Value Based API
Supports Atomic Updates
Entries Don’t Expire
Entries Aren’t Evicted
Entries Stored On-Heap
Store-By-Reference
javax.cache.Cache (Java 6)
Key-Value Based API
Supports Atomic Updates
Entries May Expire
Entries May Be Evicted
Entries Stored Anywhere (ie: topologies)
Store-By-Value and Store-By-Reference
Supports Integration (ie: Loaders / Writers)
Supports Observation (ie: Listeners)
Entry Processors
Statistics

JCache: Features
• java.util.ConcurrentMap like API
• Atomic Operations
• Lock-Free
• Read-Through / Write-Through Integration Support
• Cache Event Listeners
• Fully Generic API = type-safety
• Statistics
• Annotations (for frameworks and containers)
• Store-By-Value semantics (optional store-by-reference)

JCache: Features
• Topology Agnostic
- Topologies not defined or restricted by the specification 
• Efficiently supports:
- “local” in-memory Caching and
- “distributed” server-based Caching

JCache Key Classes/Interfaces

JCache: Runtime Structure
Caching 
“service loader”
CachingProvider 
“SPI implementation”
CacheManager 
“manager of caches”
Cache 
“interface to a Cache”
*
Created &
Managed By
Created &
Managed By
“application”
Uses..
Loads &
Tracks
*
*
*

JCache: Cache Managers
javax.cache.CacheManager
• Establishes, configures, manages and owns named Caches
- Caches may be pre-define or dynamically created at runtime
• Provides Cache infrastructure and resources
• Provides Cache “scoping” (say in a Cluster)
• Provides Cache ClassLoaders (important for store-by-value)
• Provides Cache lifecycle management

JCache: Hello World
(via a Cache Manager)
// acquire the default CacheManager
CacheManager manager = Caching.getCacheManager();
// acquire a previously configured cache (via CacheManager)
Cache<Integer, String> cache = manager.getCache(“my-cache”,
Integer.class, String.class);
// put something in the cache
cache.put(123, “Hello World”);
// get something from the cache
String message = cache.get(123);

Cache Interface & Methods (in IDE)

JCache: Entry Processors
Custom atomic operations for everyone!
// acquire a cache
Cache<String, Integer> cache = manager.getCache(“my-cache”,
String.class, Integer.class);
// increment a cached value by 42, returning the old value
int value =
cache.invoke(“key”, new IncrementProcessor<>(), 42);

public class IncrementProcessor<K>
implements EntryProcessor<K, Integer, Integer>, Serializable { 
@Override 
public Integer process(MutableEntry<K, Integer> entry,
Object... arguments) {
if (entry.exists()) {
int amount =
arguments.length == 0 ? 1 :(Integer)arguments[0];
int current = entry.getValue();
entry.setValue(count + amount);
return current;
} else {
throw new IllegalStateException(“no entry exists”);
}
}
}

• Eliminate Round-Trips! (in distributed systems)
• Enable development of a Lock-Free API! (simplifies applications) 
*May need to be Serializable (in distributed systems)
Application
CacheCache
Application

Which is better?
// using an entry processor?
int value = cache.invoke(
“key”, new IncrementProcessor<>(), 42);
// using a lock based API?
cache.lock(“key”);
int current = cache.get(“key”);
cache.put(“key”, current + 42);
cache.unlock(“key”); 
Java 8Ready!

Annotations
• JSR107 introduces a standardized set of caching annotations,
which do method level caching interception on annotated
classes running in dependency injection containers.
• Caching annotations are becoming increasingly popular:
- Ehcache Annotations for Spring
- Spring 3’s caching annotations.
• JSR107 Annotations will be added to:
- Java EE 8 (planned?)
- Spring 4.1 (released)

Annotation Operations
The JSR107 annotations cover the
most common cache operations:
• @CacheResult
• @CachePut
• @CacheRemove
• @CacheRemoveAll

Fully Annotated Class Example
@CacheDefaults(cacheName = "blogManager") 
public class BlogManager {
@CacheResult 
public Blog getBlogEntry(String title) {...}
@CacheRemove 
public void removeBlogEntry(String title) {...}
@CacheRemoveAll 
public void removeAllBlogs() {...}
@CachePut 
public void createEntry(@CacheKey String title,
@CacheValue Blog blog) {...}
@CacheResult 
public Blog getEntryCached(String randomArg,
@CacheKey String title){...}
}

JCache With Spring
• Spring
- uses JCache since 4.1 http://bit.ly/1V0q1Kp
- Added support for JCache cache annotations which can be mixed and
matched with Spring ones
• Spring Boot
- Auto-configuration for any JCache Provider http://bit.ly/1TPQKLx

JCache With Java EE
• Java EE
- Can add JCache and an implementation to any Java EE app by adding the
jars and configuring it outside of EE.
• Java EE 8
- JCache added to EE8
- Add JCache Annotations
- Other integration possibilities:
• ejb timer store
• jbatch store
• JPA
- Adam Bien is prepared to lead a JSR to get JCache into EE8. 4
contributors so far. See See https://abhirockzz.wordpress.com/2016/01/21/
jcache-in-java-ee-8/

The Future
• JCache 1.1 (2016)
- Maintenance Release being worked on, by me ☺
- Just bug fixes
• Java EE 8 Integration (2017)
• JCache 2.0 (Later)
- Transactions
- Async API
- Servlet 4.0 Integration / Session Caching

Working with Hazelcast JCache

Hazelcast JCache Support
Full TCK Compliant implementation for:
• Features:
• Embedded Members
• Clients (caches are stored in Members)
• HD Memory Store for members and near cache
• Very Fast Persistence with the Hot Restart Store
• Docs: http://bit.ly/1Q52yDz

Hazelcast JCache Performance
• Fastest IMDG using competitors
own benchmarks
• See http://bit.ly/1T36n1m
• We added JCache put/get to
Yardstick and will add it to
RadarGun.

Questions?
Greg Luck
• @gregrluck
• greg@hazelcast.com

Caching and JCache with Greg Luck 18.02.16

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