GeeCon 2017: Caching for Business Applications: Best Practices and Gotchas

Caching is relevant for a wide range of business applications and there is a huge variety of products in the market ranging from easy to adopt local heap based caches to powerful distributed data grids. Most of these caches are being promoted with examples from applications that have the luxury of having 'eventual consistency' as a non-functional requirement. Most business / enterprise applications don't have that luxury. This talks aims at developers and architects that want to adopt a caching solution for their business application. I will present 15 caching patterns and best practices for these kinds of applications that address the typical questions being asked in that context. These questions might be: 'what data can I cache?', 'how to I handle consistency in a distributed environment?', 'which cache provider to choose?' or 'how do I integrate a cache provider in my application?'. This talk comes with many live demos, some of them are run on a distributed cache cluster on Raspberry Pis

Transcript

1. Caching
 for business applications Michael Plöd - innoQ Twitter: @bitboss Kraków, 17-19 May 2017
2. I will talk about Caching Types / Topologies Best Practices for Caching in Enterprise Applications I will NOT talk about Latency / Synchronization discussion What is the best caching product on the market HTTP / Database Caching Caching in JPA, Hibernate or other ORMs
3. Cache / kæʃ / 
 
 In computing, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere. If requested data is contained in the cache (cache hit), this request can be served by simply reading the cache, which is comparatively faster. Otherwise (cache miss), the data has to be recomputed or fetched from its original storage location, which is comparatively slower. Hence, the greater the number of requests that can be served from the cache, the faster the overall system performance becomes. Source: http://en.wikipedia.org/wiki/Cache_(computing)
4. That’s awesome. Let’s cache everything and everywhere and distribute it all in a Cluster in a transactional manner ohhh by the way: Twitter has been doing that for ages Are you crazy?
5. Business-Applications !=
 Twitter / Facebook & co.
6. Many enterprise grade projects are adapting caching too defensive or too offensive and are running into consistency or performance issues because of that
7. But with a well adjusted caching strategy you will make your application more scalable, faster and cheaper to operate.
8. CACHES Types of
 Places for Local Cache, Data Grid, Document Store, JPA First Level Cache, JPA Second Level Cache, Hybrid Cache Database, Heap, HTTP Proxy, Browser, Prozessor, Disk, Off Heap, Persistence- Framework, Application
9. We will focus on local and distributed caching at the application level
10. Which data shall I cache? Where shall I cache? Which cache shall I use? Which impact does it have on my infrastructure How about data-consistency How do I introduce caching? How do I abstract my cache implementation?
11. 1 Identify suitable layers for caching
12. ComplaintManagementRestController ComplaintManagementBusinessService DataAggrgationManager Host Commands SAP Commands Spring Data Repository HTTP Caching Read Operations Read Operations Read Operations Read Operations Read and Write Operations Suitable Layers for
 Caching
13. 2 Stay local as long as possible
14. Lokal In-Memory JVM Cache
15. Clustered JVM Cache JVM Cache JVM Cache JVM Cache
16. Which data shall I cache? Where shall I cache? Which cache shall I use? Which impact does it have on my infrastructure How about data-consistency How do I introduce caching? How about caching in Spring?
17. JVM JVM JVM JVM Clustered - with sync Cache Cache Cache Cache Invalidation Replication
18. 3 Avoid real replication where possible
19. Cache Cache Cache Cache Invalidation - Option 1 #1 PUT (Insert) PUT (Insert) #1 #1 PUT (Insert) PUT (Insert) #1
20. Cache Cache Cache Cache #1 #1 PUT (Update) #1 inv #1 #1 Invalidation - Option 1
21. Cache Cache Cache Cache Invalidation - Option 2 #1 PUT (Insert) PUT (Insert) #1 #1 PUT (Insert) PUT (Insert) #1
22. Cache Cache Cache Cache #1 #1 #1 Replication #1 PUT (Insert) PUT (Update) #1
23. As of now every cache could potentially hold every data which consumes heap memory
24. Big Heap ?
25. Which data shall I cache? Where shall I cache? Which cache shall I use? Which impact does it have on my infrastructure How about data-consistency How do I introduce caching? How about caching in Spring?
26. 4 Avoid big heaps just for caching
27. Big heap leads to long major GCs Application Data Cache 32 GB
28. Long GCs can destabilize your cluster JVM Cache JVM Cache JVM Cache JVM Cache GC GC
29. Small caches are a bad idea! Many evictions, fewer hits, no „hot data“.
 
 This is especially critical for replicating caches.
30. 5 Use a distributed cache for big amounts of data
31. Distributed Caches JVM JVM JVM JVM Cache Node 1 Cache Node 2 Cache Node 3
32. 1 Customer #23 Customer #30 Customer #27 Customer #32 2
33. 1 2 Customer #23 Customer #30 Customer #27 Customer #32 BACKUP #27 BACKUP #32 BACKUP #23 BACKUP #30 Data is being distributed and backed up
34. 1 2 Customer #23 Customer #30 Customer #27 Customer #32 BACKUP #27 BACKUP #32 BACKUP #23 BACKUP #30 3
35. 3 1 2 Customer #23 Customer #30 Customer #27 Customer #32 BACKUP #27 BACKUP #32 BACKUP #23 BACKUP #30 4
36. 4 3 1 2 Customer #23 Customer #30 Customer #27 Customer #32 BACKUP #27 BACKUP #32 BACKUP #23 BACKUP #30
37. A distributed cache leads to smaller heaps, more capacity and is easy to scale Application Data Cache 2 - 4 GB … Cache
38. 6 The operations specialist is your new best friend
39. Clustered caches are complex. Please make sure that operations and networking are involved as early as possible.
40. Which data shall I cache? Where shall I cache? Which cache shall I use? Which impact does it have on my infrastructure How about data-consistency How do I introduce caching? How about caching in Spring?
41. 7 Make sure that only suitable data gets cached
42. The best cache candidates are read-mostly data, which are expensive to obtain
43. If you urgently must cache write- intensive data make sure to use a distributed cache and not a replicated or invalidating one
44. Which data shall I cache? Where shall I cache? Which cache shall I use? Which impact does it have on my infrastructure How about data-consistency How do I introduce caching? How about caching in Spring?
45. 8 Only use existing cache implementations
46. NEVER write your own cache implementation EVER
47. CACHE
 Implementations Infinispan, EHCache, Hazelcast, Couchbase, Memcache, OSCache, SwarmCache, Xtreme Cache, Apache DirectMemory Terracotta, Coherence, Gemfire, Cacheonix, WebSphere eXtreme Scale, Oracle 12c In Memory Database
48. Which data shall I cache? Where shall I cache? Which cache shall I use? Which impact does it have on my infrastructure How about data-consistency How do I introduce caching? How about caching in Spring?
49. 9 Introduce Caching in three steps
50. Optimize your application Local Cache Distributed Cache Performance Boost Performance Loss
51. 10 Optimize Serialization
52. Example: Hazelcast
 putting and getting 10.000 objects locally GET Time PUT Time Payload Size Serializable ? ? ? Data
 Serializable ? ? ? Identifier
 Data
 Serializable ? ? ?
53. Example: Hazelcast
 putting and getting 10.000 objects locally GET Time PUT Time Payload Size Serializable 1287 ms 1220 ms 1164 byte Data
 Serializable 443 ms 408 ms 916 byte Identifier
 Data
 Serializable 264 ms 207 ms 882 byte
54. JAVA SERIALIZATION
 SUCKS for Caching if alternatives are present
55. 11 Use Off-Heap Storage for Cache instances with more than 4 GB Heap Size
56. JVM Cache Runtime Cache Data 32 GB HEAP
57. Off Heap 30 GB RAM JVM Cache Runtime Cache Data 2 GB HEAP No Garbage Collection Very short Garbage Collections
58. 12 Mind the security gap
59. Application „CRM“ „Host“ DB Security Security Security Cache CRM Data SAP Data DB Data ? Mind security when reading data from the cache
60. 13 Abstract your cache provider
61. public Account retrieveAccount(String accountNumber) { Cache cache = ehCacheMgr.getCache(„accounts“); Account account = null; Element element = cache.get(accountNumber); if(element == null) { //execute some business logic for retrieval //account = result of logic above cache.put(new Element(accountNumber, account)); } else { account = (Account)element.getObjectValue(); } return account; } Tying your code to a cache provider is bad practice
62. public Account retrieveAccount(String accountNumber) { Cache cache = ehCacheMgr.getCache(„accounts“); Account account = null; Element element = cache.get(accountNumber); if(element == null) { //execute some business logic for retrieval //account = result of logic above cache.put(new Element(accountNumber, account)); } else { account = (Account)element.getObjectValue(); } return account; } Try switching from EHCache to Hazelcast You will have to adjust these lines of code to the Hazelcast API
63. public Account retrieveAccount(String accountNumber) { Cache cache = ehCacheMgr.getCache(„accounts“); Account account = null; Element element = cache.get(accountNumber); if(element == null) { //execute some business logic for retrieval //account = result of logic above cache.put(new Element(accountNumber, account)); } else { account = (Account)element.getObjectValue(); } return account; } You can’t switch cache providers between environments EHCache is tightly coupled to your code
64. public Account retrieveAccount(String accountNumber) { Cache cache = ehCacheMgr.getCache(„accounts“); Account account = null; Element element = cache.get(accountNumber); if(element == null) { //execute some business logic for retrieval //account = result of logic above cache.put(new Element(accountNumber, account)); } else { account = (Account)element.getObjectValue(); } return account; } You mess up your business logic with infrastructure This is all caching related code without any business relevance
65. <cache:annotation-driven cache-manager="ehCacheManager"/> <!-- EH Cache local --> <bean id="ehCacheManager" 
 class="org.springframework.cache.ehcache.EhCacheCacheManager" p:cacheManager-ref="ehcache"/> <bean id="ehcache" 
 class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" p:configLocation="/ehcache.xml"/> @Cacheable("Customers") public Customer getCustomer(String customerNumber) { … } Introducing Spring’s cache abstraction
66. Michael Plöd - @bitboss Kraków, 17-19 May 2017 THANK YOU!
 
 Follow me on Twitter for slides
 @bitboss