App Engine Whats Hot in Java

8/2/2019 App Engine Whats Hot in Java

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Whats Hot inJava for App EngineToby ReyeltsDon SchwarzMay 19, 2010

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Ask questions and take notes

View live notes and ask questions about

this session at:

http://bit.ly/appengine6

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http://bit.ly/appengine6http://bit.ly/appengine6http://bit.ly/appengine6


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Agenda

Java support: one year later

Dance Dance Robot

Demo

Code study

Improvements

New functionality

Performance optimizations Improved compatibility

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App Engine for Java: one year later

We host 100,000 Java applications

Over 1/3rd of all App Engine apps

We serve 1000s of requests per second

Also host many applications with large traffic spikes

e.g. Gigya Socialize

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Demo

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Game Design

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Transport

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Game Design

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Task Queues

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Game Design

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Storage

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Channel Service

Asynchronous Server Client Communication

Channel-based

Bi-directional

Server

Send messages via ChannelService object Receive messages in a web hook

Client

JavaScript library

Receive server messages in a callback

Built on Gmail chat client (Google Talk)

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Server API

Channel Service

/*** ChannelService allows you to manage two-way connections

* with clients.

*/

publicinterfaceChannelService {

/**

* Creates a channel associated with the provided applicationKey

*/String createChannel(String applicationKey);

/**

* Sends a ChannelMessage to the client.

*/

void sendMessage(ChannelMessage message);

/*** Parse the incoming message in request. This method

* should only be called within a channel webhook.

*/

ChannelMessage parseMessage(HttpServletRequest request);

}

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Client API

Channel Service

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Languages JavaScript

Java (Google Web Toolkit)

Sample codevar channel = new wnd.goog.appengine.Channel(channelId);

var socket = channel.open();

socket.onopen = function(event) {

// socket is now fully functional

};

socket.onmessage = function(event) {

// handle string msg (event.data)

};

socket.send(msg);

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Task Queue Service

Allows you to do work in the background

Up to 50 requests/sec of offline requests

Works in DevAppServer

Automatic execution at specified rates

Can see individual tasks and execute manually

Tasks can take part in a datastore transaction

Enqueue a task only when a commit succeeds

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Blobstore Service

Allows users to upload large files

File upload handled by our infrastructure

You get a callback with a blob reference

Can query, delete existing blobs

Blobs can be served back to the user (streaming)

Or retrieved a chunk at a time programatically

Images API can take blobs as input source

Useful for thumbnailing user-provided images

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Appstats

Easy to use profiling of API calls for perf tuning

In Java, usesApiProxy wrapper technique

Mentioned in last years Google I/O session

Stores API call data to memcache

Built-in servlet renders results and timing stats

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New functionality

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Datastore improvements

Cursors

Can iterate over results across HTTP requests

No more 1000 query limit

Bulk ID allocation

Makes bulk upload feasible

Opt-in to eventual consistency

Can speed up queries if stale data is good enough

Statistics

Admin Console graphs of entity counts, sizes Can be queried programmatically also

Many JDO/JPA improvements

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URLFetch improvements

Deadlines are now configurable

Up to 10 secs per request

Asynchronous API calls

Make up to 10 simultaneous calls from each request

Future-based API:

Future fetchAsync(HTTPRequest)

Other APIs will expose asynchronous APIs in the future

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Better integration through web hooks

XMPP API

Can send and receive XMPP messages

Incoming email

Receive email as an HTTP callback

Google Wave API v2

Allows active Wave robots as well as passive

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Unit testing support

Run unit tests using local API implementations

Unit testing infrastructure in a separate jar

appengine-testing.jar

ConfiguresApiProxy to discover API impls on classpath

TestConfig classes let you configure each API

Datastore disk usage disabled by default

Easily specify max memcache size

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Performance optimizations

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Precompilation

Process application bytecode at deployment time

Allows many Java libraries to work in our sandbox

Saves time during loading requests

Opportunity for more expensive optimizations

Occasionally need to re-process bytecode for all apps

Process each unique file only once

Total bytecode: only ~35 GB

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Application files (checksums)

Never-before-seen files

Compilation chunks

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Loading request latency (before and after)

Precompilation results

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ORM

JRuby

(Rack)

Rhino(Helma NG)

Real-world App #1

Real-world App #2

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Application time API calls Garbage collection

Hotspot compilation Bytecode processing

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Reflection Optimizations

Big improvements

Caching reflection access checks

Failure can be expensive

Sample Grails app

11K (!) reflective methods calls in loading request

50% against three methods

Conclusion 10% faster startup for Groovy and JRuby

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getMethod(java.lang.String.indexOf)

getMethod(ReflectTestTarget.foo)

invoke(java.lang.String.indexOf)

getDeclaredFields

getDeclaredMethods(java.lang.Object)

getConstructors(java.lang.Object)

getConstructors(java.lang.String)

getConstructors(CustomURLClassLoader)

setAccessible succeeded

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Reflection Performance Part 1

Old New

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getDeclaredFieldFailed

getDeclaredMethods(java.lang.String)

getDeclaredMethods(CustomURLClassLoader)

getDeclaredMethods(org.mortbay.jetty.Response)

setAccessible failed

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Reflection Performance Part 2

Old New

18,000!

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Future performance improvements

API call and I/O latency

Much faster memcache calls

Reduced JIT and GC time

Improved parallelization

Reserved instances

Dedicated JVMs to reduce loading requests

Will cost money, details coming soon Grants greater visibility into use of JVMs

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Improved Compatibility

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Opened up more of the JRE

Libraries

JAXB (javax.xml.bind)

StAX (javax.xml.stream)

XPath (javax.xml.xpath)

Additional classes

javax.annotation.Resource

javax.annotation.Resources

java.util.zip.ZipConstants

Many inner classes required for serialization

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More supported libraries

Just to name a few

Hessian (4.0.6)

JDOM (1.1)

Jersey (1.1.5)

MyFaces (2.0.0)

OpenAMF

PureMVC

Restlet (2.0M5)

Struts 2

Tapestry (5.1)

VRaptor (3)

Vaadin (6.1)

Wicket

...

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DevAppServer Sandbox Emulation

New

WhiteList enforced

Works for reflection, too.

Reflection permissions enforced

How?

Bytecode instrumented by JVM agent

Runtime shim modifies app behavior

All perfect then?

Unfortunately still a few corner cases

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Resources

Speakers:

Toby Reyelts

Don Schwarz

Questions and notes:

http://bit.ly/appengine6

Demo source code:

http://code.google.com/p/dance-dance-robot http://dance-dance-robot.appspot.com

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http://dance-dance-android.appspot.com/http://code.google.com/p/dance-dance-androidhttp://bit.ly/appengine6http://dance-dance-android.appspot.com/http://dance-dance-android.appspot.com/http://code.google.com/p/dance-dance-androidhttp://code.google.com/p/dance-dance-androidhttp://bit.ly/appengine6http://bit.ly/appengine6mailto:[email protected]:[email protected]:[email protected]:[email protected]


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