In-Memory Data Grids Essentials. Oracle Coherence

Scalable eCommerce Platform Solutions


In-Memory Data Grids Essentials. Oracle CoherenceVladimir KondraschenkoMax Myslyvtsev


About me

Vladimir Kondraschenko

• Lead Java engineer• More than 10 years of hands on experience in

– software design and coding– technical leadership– development management

[email protected]


Agenda

• Preconditions of using IMDG• Architecture overview– topology– distributed cache layer– local cache layer

• Cache operations• Persistence integration• Tips


Different Solutions

Coherence


Preconditions of Using IMDG

• Big amounts of data (10-100 GB)• Low latency• High availability• Distributed calculations


Transport

Local Data

Architecture Layers

Transport

Local Data

Transport

Local Data

Transport

Local Data

Transport

Local Data

Shared Data

Scalable eCommerce Platform SolutionsScalable eCommerce Platform Solutions

Transport LayerDiscovery and communication


IMDG Topology


Discovery• Multicast• Well-known address



New



WKA

WKA

New


Communication• Custom protocols over TCP or UDP• Senior node• Heartbeats

– Cluster heartbeats– Node heartbeats

Senior


Node Departure• TCP Ring• IP monitor• Timeout


Node Departure• TCP Ring• IP monitor• Timeouts


Node Departure• TCP Ring• IP monitor• Timeouts

Box1: IP 177.230.14.5

IP ping


Node Departure• TCP Ring• IP monitor• Timeout


Shared Data LayerCluster-wide data


Distributed Cache

Cluster

Client Node

Cache Interface

Storage Node

Data Storage

Cache Interface


Cache Topology

• ReplicatedStorage 1

A

D

B

E

C

F

Storage 2

A

D

B

E

C

F

Storage 3

A

D

B

E

C

F

Storage 1

A

D

B

E

Storage 2

C

A

D

F

Storage 3

E

B

F

C

• Partitioned


Storage 3

Repartitioning

Storage 1

A

D

B

E

Storage 3

E

B

F

CE

Storage 2

C

A

D

FF

FCEB


CAP Theorem

C

A

P

Coherence Coherence


Get/Put/Remove, Query, Invocation, Map-Reduce

Cache operations


Key hashing

Cache Operations: Put/Get

Storage 1 Storage 2

Client

Primary A

A B C D E F

• Client knows responsible storage– Key hash is used to find it

• Automatic backups

Backup A

Backup F Primary F


Storage 2Storage 2Storage 1

Cache Operations: Query• Broadcast request

– Unless Query is Key-Associated• All entries are evaluated

– Unless Indexes are used

field1=10 or field2>70field1=10 and key=A

key:field1:field2:

D7080

key:field1:field2:

C5060

key:field1:field2:

B3040

key:field1:field2:

D7080

key:field1:field2:

C5060

key:field1:field2:

B3040

key:field1:field2:

A1020


Cache Operations: Invocation/Entry Processor• Task is serialized and distributed

– May contain additional data• Configurable execution scope

– Specific nodes– All nodes– Nodes bound to data

Node 1 Node 2

Task Task

Client

Task


• Data-bound mapping– By keys– By Query

• Parallel execution

Storage 2Storage 1

key:field1:field2:

A1020

key:field1:field2:

B3040

key:field1:field2:

C5060

key:field1:field2:

D7080

Cache Operations: Map-Reduce

sum(field2) where field1>20

40 60 80

180

key:field1:field2:

A1020

140


Persistence integration


Synchronous Persistence Integration

• Read-through

• Write-through

StorageClient Durable Storage

Data Grid

Client Durable Storage

Data GridStorage


• Refresh-ahead

• Write-behind

Asynchronous Persistence Integration

Storage QueueClient Durable Storage

Data Grid

Storage QueueClient Durable Storage

Data Grid


Local Data LayerNode-specific data


Storage Storage

Node

Near Caching• Local access by primary key• Lazy population• Invalidation

– On entry change– By timeout

Near Cache

Distributed Cache

A

A B


Continuous Caching• Local access by any Query• Eager population• Near real-time data

Storage Storage

Node

Continuous Cache

Distributed Cache

A B

A B


TipsUsing Oracle Coherence in practice


Before integrating Oracle Coherence• Do I really need IMDG or just a cache?• How large my cluster should be?• How much heap memory should be

configured for each node?• What GC configuration to use?• Do I have a relevant environment

to test my application?


Memory usageLimit cache size• By binary size (per node)• By number of objects in cache (per node)

Estimate cache object memory consumption• Use BinaryMemoryCalculator• Remember about backup copies• Cache listeners (near cache, custom)


Investigation & troubleshooting• Coherence Management Framework (JMX)

– view cluster and nodes settings– list caches (front and back) on each node– view cache dynamic metrics

• Coherence command-line tool– manage cache services– manipulate cache data

• Profiling and heap analysis– analyze heap dump– analyze GC logs



Thank you!Questions & Answers


References• Workshop

– https://github.com/mmyslyvtsev/imdg-workshop• Coherence Knowledge Base

– http://coherence.oracle.com• Developers Guide

– http://docs.oracle.com/cd/E18686_01/coh.37/e18677/toc.htm• Book

– http://www.amazon.com/Oracle-Coherence-3-5-Aleksandar-Seovic/dp/1847196128

https://github.com/mmyslyvtsev/imdg-workshop



http://coherence.oracle.com/

http://docs.oracle.com/cd/E18686_01/coh.37/e18677/toc.htm

http://docs.oracle.com/cd/E18686_01/coh.37/e18677/toc.htm

http://www.amazon.com/Oracle-Coherence-3-5-Aleksandar-Seovic/dp/1847196128

http://www.amazon.com/Oracle-Coherence-3-5-Aleksandar-Seovic/dp/1847196128

In-Memory Data Grids Essentials. Oracle Coherence

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