The Globals Database

Its significance for Node.js developers

Rob TweedM/Gateway Developments Ltd

http://www.mgateway.comTwitter: @rtweed

Background

• Director, M/Gateway Developments Ltd• Web/Ajax/Mobile web technologies• Healthcare, Financial Services• Business/enterprise applications

– Browser-based– Interactive– Secure– Internet & Intranet– Database intensive

What databases?

• “Global storage-based”– Caché (“native storage”) – GT.M

• Very high performance & reliability• Very low maintenance• NoSQL database that pre-dates the NoSQL era• Tried and tested for business-critical use• Dominate healthcare and financial services• Much wider applicability, but generally little

known– Key limitation: accessed via an outdated language

What’s my interest in Node.js?

• Using Javascript since late 1990’s

• Douglas Crockford– “Loopage”

• Javascript on the server– Direct access to global storage via

Javascript?

Globals Database

http://globalsdb.org

What is Globals?

• Core database engine from Caché• No native language• None of Caché’s object/relational functionality• Just the core global-storage engine• Free

– But not Open Source– Otherwise extremely liberal licence

• Two APIs:– Java– Node.js

Global storage

• Global Persistent Variables– aka “Globals”

• Globals = unit of persistent storage– Schema-free– Hierarchically structured– Sparse– Dynamic

– “persistent associative array”

– Each array element = “a global node”

Anatomy of a Global Node

• A Global node has:– A name– 0, 1 or more subscripts– String value

globalName[subscript1,subscript2,..subscriptn] == value

Simple key/value storage

telephone“617-555-1414” “Tweed, Rob”

“211-555-9012” “James, George”

telephone[“617-555-1414”] == “Tweed, Rob”

Multi-dimensional structures“firstNode” 5

“lastNode” 2

“node”

4

list “myList”

“nodeCounter” 5

“nextNode” 2

“previousNode” 5

“value” “George”

5“nextNode” 4

“value” “Rob”

2“value” “John”

“previousNode” 4

Globals = Universal NoSQL Engine

• Document storage– Automatic mapping to/from JSON

• Columnar

• Graph

• Native XML database

• Relational

• Object

Global storage as a db technology

• Low-level storage engine• No built-in indexing

– You create/define the indices you need

• Schema-free– Database behaviour defined in your application logic

• No built-in query language– APIs for node hierarchy traversal

• All the basic building blocks for creating your own tailored NoSQL database

Why bother?

• Lots of Open Source NoSQL databases for Node.js:– Redis– CouchDB– MongoDB– Riak– etc

Globals Node.js APIs

• In-process– No network layer

• API style:– Asynchronous– Synchronous

Why Globals? My view:

• Ridiculously high performance

• One single multi-purpose database

• Synchronous coding

Objection, m’lud!

In-process database

• That sounds like too intimate a relationship– A problem in the database will bring down the

Node.js process

• On the other hand…– No network bottleneck– Potential for very high performance

Synchronous APIs

Gospel according to St. Async of the Node

Introducing Q-Oper8

https://github.com/robtweed/Q-Oper8

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Incoming request

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

If necessary,Put it on the

queue

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

If child process

is free, sendfirst request

Queueprocessingtriggered

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Child process unavailable

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Process request

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Finished:Send back

result object

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Process resultand sendresponse

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Child process available

Q-Oper8 architecture

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Queueprocessingtriggered

Q-Oper8 benefits

• Child processes can use blocking I/O– Only handle one request at a time– Nobody else to block

• Main server process uses kosher async logic• Main process is isolated from activity in child

processes:– Blocking I/O– Synchronous coding– Heavy computation– in-process database

• Allows Node.js to use multiple CPU cores

Q-Oper8 + Globals

Main Node.js server process

Pre-spawned Child processes

Queue ofrequest objects

Pure asyncactivityhere

Globalsdb APIs

Globalsdb APIs

Globalsdb APIs

Q-Oper8 + Globals Performance

• My test machine:– HP Proliant ML115G Server

• 4-core AMD Opteron 2.1GHz CPU• 8 Gb memory• 640 Gb 7200 RPM SATA hard drive

– (Western Digital Caviar Blue)

– Ubuntu Linux 10.10 Server (64-bit)– Node.js 0.4.0– Globals DB

– Under £200-worth of machine

Q-Oper8 No-op test

• Passing simple message each way– No other processing

• Determine “steady state”:– Add requests to queue as fast as child

processes can process them

• Optimum performance with 3 child processes

• 18,350 per second

Q-Oper8 + Globals

• Increasing numbers of Set commands per request– Each Set creates one new global node

• Different APIs:– Async parallel– Async nested– Sync

• Measured steady-state maximum rate

Q-Oper8 + Globals

Q-Oper8 + Globals

Sync

Async parallel

Async nested

Requests/sec

No of Global Sets per request

1 2 5

Q-Oper8 + Globals

Requests/Sec

(Sync)

No of Global Sets per request

1000500200100

Q-Oper8 + Globals

Global sets/Sec

(Sync)

No of Global Sets per request

1000500200100

Conclusions

• Globals’ synchronous APIs are more than twice as fast as its asynchronous ones

• The more Globals activity you do per request, the better the db performance

• On my small server, performance maxed at 190,000 global node sets/sec– Redis-benchmark on same server: 88,000

Sets/sec

Globals in Use

• ewdDOM module– Persistent XML DOM implementation– Uses Globals for storage– DOMs created and stored in globals– Access to DOMs is via synchronous APIs– APIs hit the data in situ, not an in-memory

copy

– https://github.com/robtweed/ewdDOM

ewdDOM: Example

var document = ewdDOM.getDocument('rob'); var node1 = document.createElement("testElement"); document.getElementById('myNode').appendChild(node1); document.getElementById('myNewNode').text = ‘Some new text'; document.output();

• Synchronous logic allows full use of OO syntax

• Each level in the “dot syntax” represents a number of global node manipulations, with result passed to its child method

• Not feasible using async logic with call-backs

Globals in Use

• M/DB-g– Emulation of Amazon SimpleDB– 100% API-compatible– Development history:

• Pure global database native-language implementation (Caché and GT.M)

• Node.js + async access to GT.M– Painful! Incomplete

• Node.js + sync access to Globals– Easy! Line by line copy of original implementation

Sync v Async

• Async perfect for event-handling and other I/O• Globals makes sync coding possible for

database access/manipulation– Higher performance– Easier and quicker to write– Much simpler to maintain– Allows creation of higher-level OO APIs– Node.js for business/enterprise applications becomes

feasible to consider• Developer and maintenance time = the primary IT costs

Globals: Conclusion

• Significance:– Extremely high performance database for use

with Node.js– Very adaptable database engine (universal

NoSQL engine)• One database for all needs• “virtual storage” for Node.js?

– Possibility of synchronous database coding

Appendix

Macbook Air benchmark

• OS X Lion

• Ubuntu 10.10 VM + Fusion 3

• 1 CPU + 512Mb memory:– 1 Q-Oper8 child process– Max global sets: ~ 38,000 / sec

• 2 CPU + 512Mb memory:– 2 Q-Oper8 child process– Max global sets: ~ 77,000 / sec

ewdDOM Benchmark

• Create small DOM programmatically– 177 X Write:

• 164 X set• 13 X kill

– 322 X Read:• 110 X get• 212 X data

• 1000 requests put on Q-Oper8 queue• 3.5 seconds to process

– 92,000 reads/sec + 50,570 writes/sec