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Andreas Grabner - @grabnerandi

Biggest Performance Mistakes (.NET, Java, Web …)

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That’s why I ended up talking about performance

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Nobody wants this …

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Unless you work for Google or Microsoft

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Nor this …

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As it leads to this …

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The “War Room”

Facebook – December 2012

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And potentially to this …

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And this …

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And that’s why Business doesn’t like it either …

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~80% of problems

caused by ~20% patterns

YES we know this

80% Dev Time in Bug Fixing

$60B Defect Costs

BUT

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6 Situations on

WHY this happened,

HOW to avoid it,

METRICS to look at

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Incorrect Sizing of Pools and

Queues

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Online Banking: Slow Balance Check

1.69s (=101s!) To Check Balance!

87% spent in IIS 600! SQL Executions

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#1 Time really spent in IIS?

Tip: Elapsed Time tells us WHEN a Method was executed!

Finding: Thread 32 in IIS waited 87s to pass control to Thread 30 in ASP.NET

Tip: Thread# gives us insight on Thread Queues / Switches

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#2 What about these SQL Executions?

Finding: EVERY SQL statement is executed on

ITS OWN Connection!

Tip: Look at “GetConnection”

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#2 SQL Executions! continued …

#1: Same SQL is executed 67! times

#2: NO PREPARATIONbecause everything

executed on new Connection

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Lessons Learned!

ASP.NET Worker Thread Pool Sizing!

DB Connection PoolsMore Efficient SQL

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Idle vs. Busy Threads

# SQLs / Request

# GetConnection

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“Blindly” (Re)use Existing

Components

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Requirement: We need a report

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Using Hibernate results in 4k+ SQL Statements to display 3 items!

Hibernate Executes 4k+ Statements

Individual Execution VERY FAST

But Total SUM takes 6s

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• Proper Sizing Specifications

• Understand the Frameworks you are using

Lessons Learned

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# SQLs / Request

# Same SQL / Request

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Wrong Tools for the Job

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#1 Banking: Transaction History CSV Download!

Remember: High GC doesn’t necessarily mean that this request has a memory problem – BUT - …

Root Cause: Heavy use of String.Concat to build the CSV output in Memory

Recommendations:#1: Use System.Text.StringBuilder instead of String.Concat#2: Write directly back to OutputStream

Problem: Takes 207s! To download. 87% of Time spent in Garbage

Collection

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#2 Store: Rendering Search ResultProblem: 4.4s to render

result page

Root Cause: Custom RegExLibrary with performance

issues on large strings

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#3 Store: Occasional Performance Spikes

Problem: Occasional Spikes!Never seen in Development

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First Analysis: His own code

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DNS Lookup Issue during Login

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Reverse Lookup by IP fails on these IPs

Root Cause: Issues from Data Center Hoster

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• CSV Export Example

• Don’t build large Strings in Memory with String.Concat

• Write to output stream and use StringBuilder

• Search Result Page

• Don’t implement custom RegEx Library – existing Tools are better

• Test with large results and not just small test data

• Geo Lookup

• Don’t trust your Hosting Provider

• E.g: Use GeoIP Databases for accurate reverse lookups

Lessons Learned – Use Better Tools / Libraries

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Memory Usage

Time Spent in APIs

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Not every Architect makes good decisions

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• Symptoms

• HTML takes between 60 and 120s to render

• High GC Time

• Assumptions

• Bad GC Tuning

• Probably bad Database Performance as rendering was simple

Project: Online Room Reservation System

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Developers built own monitoring

void roomreservationReport(int roomid)

{

long startTime = System.currentTimeMillis();

Object data = loadDataForRoom(roomid);

long dataLoadTime = System.currentTimeMillis() - startTime;

generateReport(data, roomid);

}

Result:

Avg. Data Load Time: 45s!

DB Tool says:

Avg. SQL Query: <1ms!

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#1: Loading too much data24889! Calls to the

Database API!

High CPU and High Memory Usage to keep all

data in Memory

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#2: On individual connections 12444!individual

connections

Classical N+1 Query Problem

Individual SQL really <1ms

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#3: Putting all data in temp Hashtable

Lots of time spent in

Hashtable.get

Called from their Entity Objects

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• Custom Measuring

• Was impacted by Garbage Collection

• Just measured overall time but not # SQL Executions

• Learn SQL and don’t use Hashtables as Workaround

Lesson Learned

void roomreservationReport(int roomid)

{

long startTime = System.currentTimeMillis();

Object data = loadDataForRoom(roomid);

long dataLoadTime = System.currentTimeMillis() - startTime;

generateReport(data, roomid);

}

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# SQL Executions

# of SAME SQLs

Conn. Acquisition Time

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#Push without a Plan

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Mobile Landing Page of Super Bowl Ad

434 Resources in total on that page:230 JPEGs, 75 PNGs, 50 GIFs, …

Total size of ~ 20MB

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Fifa.com during Worldcup

http://apmblog.compuware.com/2014/05/21/is-the-fifa-world-cup-website-ready-for-the-tournament/

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# Images

# Redirects

Size of Resources

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#No “Agile” Deployment

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Load Spike resulted in UnavailabilityAd

on

air

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Alternative: “GoDaddy goes DevOps”

1h before SuperBowl KickOff

1h after Game ended

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# of Domains

Total Size

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Waiting for Bug Reports

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Look behind the scenes

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•# Images

•# Redirects

•Size of Resources

•# SQL Executions

•# of SAME SQLs

•# Items per Page

•# AJAX per Page

Look at these Metrics Before Checking In Code

•Time Spent in API

•# Calls into API

•# Functional Errors

•3rd Party calls

•# of Domains

•Total Size

•…

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Commit Stage• Compile• Execute Unit Test• Code Analysis• Build installers

Automated Acceptance

Testing

Automated Capacity Testing

Manual testing• Key showcases• Exploratory testing Release

Unit & Integration Tests

Functional Tests

Performance TestsProductionMonitoring

Functional Tests

(R)Evolutionize Performance Optimization

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Example from Web Diagnostics 282! Objects

on that page9.68MB Page Size

8.8s Page Load Time

Most objects are images delivered from your main

domain

Very long Connect time (1.8s) to your CDN

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Example from Server-Side Diagnostics526s to render that

report

1 SQL running

210s!

Lots of time spent in logging to Log4J

Lots of time spent in rendering

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Online Performance Clinics

Every Other week @

bit.ly/onlineperfclinic

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Your Benefits

• Free Performance Review

• Extended Dynatrace License

“Share Your PurePath”

bit.ly/sharepurepathMy Benefits

• More blog material for next year

• Gratification that I could help you

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Questions and/or Demo

Slides: slideshare.net/grabnerandi

Get Tools: bit.ly/dttrial

YouTube Tutorials: bit.ly/dttutorials

Contact Me: agrabner@dynatrace.com

Follow Me: @grabnerandi

Read More: blog.dynatrace.com

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Andreas GrabnerDynatrace Developer Advocate

@grabnerandi

http://blog.dynatrace.com