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Andrew Duncan Managing Director, SwarmOnline Member No. 149387 @andrewduncan andrew@swarmonline.com © 2015 SwarmOnline

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1. Memory Management 2. Tools of the trade MEMORY LEAK HEALTH CHECK Our Quest to Diagnose & Cure © 2015 SwarmOnline

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WHY IS THIS TOPIC IMPORTANT? • Move to richer / interactive applications • More use of JavaScript to achieve this • Single Page Applications • Cross integration of multiple frameworks and technologies • Multiple device types, operating systems and browsers © 2015 SwarmOnline

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MEMORY LEAK DEFINITION mem . o . ry leak noun COMPUTING noun: memory leak; plural noun: memory leaks a failure in a program to release discarded memory, causing impaired performance or failure. © 2015 SwarmOnline

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YES • Garbage Collection NO • Coding Mishaps DOESN’T THIS GET HANDLED FOR ME? © 2015 SwarmOnline

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WHAT TOOLS DO WE HAVE © 2015 SwarmOnline

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CHROME & DEVELOPER TOOLS •Task Manager •Timeline •Profiles © 2015 SwarmOnline

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TASK MANAGER © 2015 SwarmOnline

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•1st round of testing •Instantaneous view of memory •Useful for monitoring changes over small periods of time TASK MANAGER © 2015 SwarmOnline

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TIMELINE © 2015 SwarmOnline

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• Monitors memory over time • Sudden drops === GC • Look out for two things: • Steady rise in the chart • GC not returning to original memory usage TIMELINE © 2015 SwarmOnline

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PROFILES © 2015 SwarmOnline

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PROFILES •Identify increase in objects •Do comparison © 2015 SwarmOnline

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RECORD HEAP ALLOCATIONS © 2015 SwarmOnline

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RECORD HEAP ALLOCATIONS © 2015 SwarmOnline

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N.B. • Memory is skewed just by having Chrome Developer Tools open • Observer Effect © 2015 SwarmOnline

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OTHER BROWSER TOOLS All of these browsers have tools that can be used to monitor memory • Internet Explorer • Safari • Firefox © 2015 SwarmOnline

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INTERNET EXPLORER DEVELOPER TOOLS © 2015 SwarmOnline

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SAFARI FOR DEVELOPERS © 2015 SwarmOnline

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FIREFOX DEVELOPER © 2015 SwarmOnline

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TASK MANAGER & WINDOWS TOOLS • Record memory usage in Perfmon & PsTools (PsList) • Plot and view memory usage over time • In our case 1 hour, 24 hours, 1 week, 1 month PsTools PsList © 2015 SwarmOnline

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TASK MANAGER & WINDOWS TOOLS Pipe data out to CSV for charting © 2015 SwarmOnline

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AUTOMATE MEMORY MONITORING How do we do this? • Virtual Machines • Auto snapshot every X minutes • Reduce Observer Effect • Graph your results © 2015 SwarmOnline

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HOW TO DO THIS YOURSELF • Strip it back to basics • App in container only • Send data but don’t enable parsing • Add in the data package • If your app has multiple parsers for different types of data, enable each data packet individually • Gradually add in your controllers and view • Each view will need tested individually • Create your app with only one view enabled • We run over 30 VM’s with different versions of an app to get as much coverage as possible © 2015 SwarmOnline

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HOW TO DO THIS YOURSELF (2) • If you suspect something is going wrong • Take snapshot • Run code • Take snapshot • Review differences • Obviously new data (e.g. Ajax requests) are going to skew your results between snapshots © 2015 SwarmOnline

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FINAL THOUGHTS • If all else fails… • Or in extreme circumstances…rm -rf* © 2015 SwarmOnline

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Andrew Duncan Managing Director, SwarmOnline @andrewduncan andrew@swarmonline.com © 2015 SwarmOnline