The new ehcache 2.0 and hibernate spi

Caching, and what’s new in Ehcache 2 and Hibernate Caching Provider Thursday, 17 June 2010

Why Cache? Reasons to cache:  Offload - reducing the amount of resources consumed and hence cost  Performance - increasing the speed of processing  Scale out - distributed caching is a leading scale-out architecture www.terracotta.org 2 Thursday, 17 June 2010

Truncating the request-response Loop load balancer load balancer HTTPD HTTPD HTTPD Application Application server server ehcache ehcache Terracotta ... Terracotta Terracotta Server ... Terracotta Server MySQL Server Database stripe 1 Server stripe n stripe 1 stripe n www.terracotta.org 3 Thursday, 17 June 2010

Amdahl’s Law  Amdahl's law, after Gene Amdahl, is used to find the system speed up from a speed up in part of the system. 1 / ((1 - Proportion Sped Up) + Proportion Sped Up / Speed up)  To apply Amdahl’s law you must measure the components of system time and the before and after affect of the perf change made.  It is thus an empirical approach.  Not recommended is the other approach “When all you have is a hammer every problem looks like a nail”. Lots of times it is something completely new. However very few developers will take the time to make careful measurements. www.terracotta.org 4 Thursday, 17 June 2010

Cache Efficiency cache efficiency = cache hits / total hits ➡ High efficiency = high offload ➡ High efficiency = high performance www.terracotta.org 5 Thursday, 17 June 2010

Why does caching work?  Locality of Reference  Pareto Distributions www.terracotta.org 6 Thursday, 17 June 2010

Locality of Reference  Many computer systems exhibit the phenomenon of locality of reference.  Data that is near other data or has just been used is more likely to be used again. Temporal locality - refers to the reuse of specific data and/or resources within relatively small time durations. Spatial locality - refers to the use of data elements within relatively close storage locations  e.g. this is the reason for hierarchical memory design in computers www.terracotta.org 7 Thursday, 17 June 2010

Pareto Distributions  Chris Anderson, of Wired Magazine, coined the term The Long Tail to refer to Ecommerce systems.  The mathematical term is a Pareto Distribution aka Power Law Distribution. www.terracotta.org 8 Thursday, 17 June 2010

Another Problem... But...  What if the data set is too large to fit in the cache?  What about staleness of data www.terracotta.org 9 Thursday, 17 June 2010

Coherency with SOR  classically solved with an automatic expiry. Ehcache has both TTL and TTI. Better:  Eternal caching plus a cache invalidation protocol  Write-through or behind caches. The SOR gets updated in-line with the cache. Hibernate read-write and transactional strategies are examples. Also Ehcache CacheWriter www.terracotta.org 10 Thursday, 17 June 2010

Why run a cluster?  Availability, most often n+1 redundancy  Scale out But this creates a new cascade of problems: • N * problem • Cluster coherency problem • CAP theorem limits www.terracotta.org 11 Thursday, 17 June 2010

N * Problem  On a single node work is done once and then cached. Cache hits offload. But in a cluster the work must be done N times, where N is the number of nodes  The solution to the N * times problem is a replicated or distributed cache  replicated cache - the data is copied to each node. All data is held in each node  distributed cache - the most used data is held in a node. The balance of the data is held outside the application node www.terracotta.org 12 Thursday, 17 June 2010

Cluster Coherency Problem  Each cache makes independent cache changes. The caches become different  Solved partly by a replicated or distributed cache  But, without locking, race conditions will cause incoherencies  Solution is a coherent, distributed or replicated cache www.terracotta.org 13 Thursday, 17 June 2010

CAP Theorem PACELC The CAP theorem, also known as Brewer's theorem, states that it is impossible for a distributed computer system to simultaneously provide all three of the following guarantees: consistency, availability and tolerance to partition. A better explanation of the tradeoffs is PACELC: if there is a partition (P) how does the system tradeoff between availability and consistency (A and C); else (E) when the system is running as normal in the absence of partitions, how does the system tradeoff between latency (L) and consistency (C)? There is no right answer, but the properties to be traded off will be different for different applications. So the solution must be configurable. 1. http://dbmsmusings.blogspot.com/2010/04/problems-with-cap-and-yahoos-little.html www.terracotta.org 14 Thursday, 17 June 2010

About Ehcache The world's most widely used Java cache  Founded in 2003  Apache 2.0 License  Integrated by lots of projects, products  Hibernate Provider implemented 2003  Web Caching 2004  Distributed Caching 2006  Greg Luck becomes co-spec lead of JSR107  JCACHE (JSR107) implementation 2007  REST and SOAP APIs 2008  SourceForge Project of the Month March 2009  Acquired by Terracotta 2009; Integrated with Terracotta Server  Ehcache 2.0 March 2010  Forrester Wave “Leader” May 2010 www.terracotta.org 15 Thursday, 17 June 2010

Ehcache 2 16 Thursday, 17 June 2010

Ehcache before Terracotta www.terracotta.org 12 17 Thursday, 17 June 2010

Ehcache after Terracotta www.terracotta.org 13 18 Thursday, 17 June 2010

Adding a specific ehcache.xml ehcache.xml: <ehcache> <defaultCache maxElementsInMemory="10000" eternal="false" timeToLiveSeconds="120" /> <cache name="org.hibernate.cache.UpdateTimestampsCache" maxElementsInMemory="10000" timeToIdleSeconds="300" /> <cache name="org.hibernate.cache.StandardQueryCache" maxElementsInMemory="10000" timeToIdleSeconds="300" /> </ehcache> www.terracotta.org 15 19 Thursday, 17 June 2010

Adding Terracotta ehcache.xml <ehcache> <terracottaConfig url="someserver:9510"/> <defaultCache maxElementsInMemory="10000" eternal="false" timeToLiveSeconds="120" /> <cache name="com.company.domain.Pets" maxElementsInMemory="10000" eternal=”true”> <terracotta clustered="true" coherent="false"/> </cache> <cache name="com.company.domain.Clinics" maxElementsInMemory="10000" timeToLiveSeconds="3000"> <terracotta clustered="true" coherent="true"/> </cache> </ehcache> www.terracotta.org 16 20 Thursday, 17 June 2010

Ehcache 2 - New Features Hibernate 3.3+ Caching SPI Old SPI was heavily synchronized and not well suited to clusters New SPI uses CacheRegionFactory Fully cluster safe with Terracotta Server Array Unification of the Ehcache and Terracotta 3.2 providers JTA i.e. transactional caching strategy JTA Cache as an XAResource Detects most common Transaction Managers Others configurable Works with Spring, EJB and manual transactions www.terracotta.org 21 Thursday, 17 June 2010

Ehcache 2 - New Features Write-behind Offloads Databases with high write workloads CacheWriter Interface to implement cache.putWithWriter(...) and cache.removeWithWriter(...) Write-through and Write-behind modes Batching, coalescing and very configurable Standalone with in-memory write-behind queue. TSA with HA, durability and distributed workload balancing Bulk Loading incoherent mode for startup or periodic cache loading 10 x faster No change to the API (put, load etc). SetCoherent(), isCoherent(), waitForCoherent() www.terracotta.org 22 Thursday, 17 June 2010

Ehcache 2 - New Features ...cont. New CAP configurability – per cache basis coherent – run coherent or incoherent (faster) synchronousWrites – true for ha, false is faster copyOnRead – true to stop interactions between threads outside of the cache Cluster events – notification of partition and reconnection NonStopCache - decorated cache favouring availability UnlockedReadsView - decorated cache favouring speed Management Dynamic Configuration of common cache configs from JMX and DevConsole New web-based Monitoring with UI and API www.terracotta.org 23 Thursday, 17 June 2010

Ehcache 2.0 Monitoring Options  JMX • is built in to Ehcache but... • JMX needs use portmap • Slow • Machines may be headless  Terracotta Dev Console (if using Terracotta)  Ehcache Console, new in 2.1 www.terracotta.org 24 Thursday, 17 June 2010

Including Web Services Simple + Performant + Coherent + HA + Scaleable Application Ehcache Terracotta Terracotta Server Server Application Ehcache Terracotta Terracotta Server Server Application Ehcache Terracotta Terracotta Server Server PHP App C App Web Container REST/ Ehcache C# App HTTP Server Ruby App www.terracotta.org 25 Thursday, 17 June 2010

Terracotta Developer Console Cache hit ratios Hit/miss rates Hits on the database Cache puts Detailed efficiency of cache regions Dramatically simplifies tuning and operations, and shows the database offload. www.terracotta.org 26 Thursday, 17 June 2010

Ehcache Console  Web based  Configuration  Efficiency  Memory Use  Comes with supported versions  API to connect Operations Monitoring www.terracotta.org 27 Thursday, 17 June 2010

Exploring Hibernate Caching: Spring Pet Clinic 28 Thursday, 17 June 2010

Code - Spring Pet Clinic www.terracotta.org 29 Thursday, 17 June 2010

Pet Clinic Domain Model Domain Objects Sprint PetClinic Domain Model  Vets Vet Specialty attr = "" attr = ""  Specialty  Owner  Pet Owner attr = ""  PetType  Visit Pet PetType attr = "" attr = "" Visit attr = "" www.terracotta.org 30 Thursday, 17 June 2010

Code Steps:  Configure PetClinic for Hibernate  Configure hibernate for second-level cache  Configure hbm file for caching  Update query code to add caching Optional but recommended:  add ehcache.xml to WEB-INF/classes  specify cache regions and config www.terracotta.org 31 Thursday, 17 June 2010

Code ehcache.xml: <ehcache> <defaultCache maxElementsInMemory="10000" eternal="false" timeToLiveSeconds="120" /> <cache name="org.hibernate.cache.UpdateTimestampsCache" maxElementsInMemory="10000" timeToIdleSeconds="300" /> <cache name="org.hibernate.cache.StandardQueryCache" maxElementsInMemory="10000" timeToIdleSeconds="300" /> </ehcache> www.terracotta.org 32 Thursday, 17 June 2010

Performance 33 Thursday, 17 June 2010

Performance  Testing Methodology  Results in Details  Conclusions www.terracotta.org 34 Thursday, 17 June 2010

Standalone Performance  Read Performance www.terracotta.org 35 Thursday, 17 June 2010

Standalone Performance  Put Performance www.terracotta.org 36 Thursday, 17 June 2010

Ehcache in-process vs Memcached www.terracotta.org 37 Thursday, 17 June 2010

REST Performance Ehcache Server Memcache 4000 3000 2000 1000 0 Get Multi-Get Put Remove Source: MemcacheBench with Java clients. Time for 10,000 operations www.terracotta.org 38 Thursday, 17 June 2010

Ehcache with Terracotta vs the Rest  Application  Tests done with Owners = 25K and 125K which translates to total objects of 0.3 M and 1.5 M  Minimal tuning.  Cluster Configuration:  8 Client JVMs (1.75G Heap)  1 (+0) Terracotta Servers (6G Heap)  MySql: sales18. www.terracotta.org 39 Thursday, 17 June 2010

Ehcache with Terracotta vs the Rest  Ehcache  Replicated with RMI not included because not coherent  Single TSA Server  15 threads and some with 100 threads  IMDG  15 threads  Cache deployed in Partitioned Mode  Tests were also done with Replicated – which did well for small cache sizes but failed to complete with larger cache sizes. So, it is not included.  memcached  15 threads  1 server www.terracotta.org 40 Thursday, 17 June 2010

Hibernate - Read Only TPS www.terracotta.org 41 Thursday, 17 June 2010

Hibernate - Read Write TPS www.terracotta.org 42 Thursday, 17 June 2010

Hibernate - Read Only Latency www.terracotta.org 43 Thursday, 17 June 2010

Hibernate - Read Write Latency www.terracotta.org 44 Thursday, 17 June 2010

Test Source The code behind the benchmarks is in the Terracotta Community SVN repository. Download https://svn.terracotta.org/repo/forge/ projects/ehcacheperf/ (Terracotta Community Login Required) www.terracotta.org 45 Thursday, 17 June 2010

Performance Conclusions With Hibernate, Using Spring Pet Clinic After app servers and DBs tuned by independent 3rd parties 30-95% database load reduction 80 times read-only performance of MySQL Notably lower latency 1.5 ms versus 120 ms for database (25k) www.terracotta.org 46 Thursday, 17 June 2010

What about NoSQL?  Ehcache + Terracotta configured with persistence gives you a NoSQL store with limited features i.e. no search  TerraStore - new open source project from Sergio Bossa is a document oriented NoSQL store based on Terracotta and ful www.terracotta.org 47 Thursday, 17 June 2010

Wrap Up 48 Thursday, 17 June 2010

Q&A Please ask any questions you have in the Q&A window. www.terracotta.org 49 Thursday, 17 June 2010

Additional Ehcache Information  Website: www.ehcache.org  Documention: www.ehcache.org/documentation  Hibernate: www.ehcache.org/documentation/ hibernate.html  Commercial Products: www.terracotta.org/ehcache/  Twitter: www.twitter.com/Ehcache www.terracotta.org 50 Thursday, 17 June 2010

Terracotta Contact Information  Website: www.terracottatech.com  Telephone: +1 415-738-4000  Email: info@terracottatech.com  Facebook: www.facebook.com/Terracotta  Twitter: www.twitter.com/TerracottaTech www.terracotta.org 51 Thursday, 17 June 2010

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The new ehcache 2.0 and hibernate spi

by Cyril Lakech

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