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Unreal Journal
Trash Compactor

Trash Compactor

We recently found a huge leak in the UE4 garbage collector, particularly rearing its head on dedicated servers for large open-world games. Servers for arena type games with short play times (<1 hour) seem to be little affected, and clients don’t see the problem much either. “Huge” is not hyperbole here – we’re talking the garbage collector alone using up to 10 GB of ram in under 24 hours of server operation!
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Placating The Natives

Placating The Natives

In this article we delve into Blueprint Nativization, a relatively new feature of UE4 that offers significant performance improvements for many projects. Sadly, it often doesn't work out of the box - we've spent some time fixing and improving it for a particular project that we were working on. We have a LOT of changes to present here - some of which have already been implemented into UE4.
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PhysX: The Case Of The Leaky Cloth

PhysX: The Case Of The Leaky Cloth

We found quite a large leak within Apex 3.4 (currently used in Unreal Engine 4, amongst others) - in a relatively short run of the title that we were working on, we saw over 150mb of leaked memory. Here, we present some changes that will fix this
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So Long MAX_PATH… And Thanks For All The Fish!

So Long MAX_PATH… And Thanks For All The Fish!

Almost every developer that we've spoken to seems to have, at some point, encountered the MAX_PATH limit problem... this post talks about how to PROPERLY fix it
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Is It A Drive? Is It A Directory? No, It’s…

Is It A Drive? Is It A Directory? No, It’s…

In this post, we look into why IPlatformFileCreateDirectory() was responsible for nearly 1 million allocations during a full cook of KiteDemo and why FPaths::IsDrive(), a huge 100-line function, is being used just to determine whether a filepath begins with a drive mapping... all for the purpose of further speeding up Unreal's cook process just a little bit more
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Cache-ing Up, Cache-ing In

Cache-ing Up, Cache-ing In

As part of modifying the file profiler we looked at the file IO activity on starting the UE4 editor with one of the lightweight sample projects, noticing that certain files were being read multiple times. Each was being read in their entirety up to 200 times simply opening the editor. In this post we show you why this was happening and how it can be fixed
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The Case of the Locked File

The Case of the Locked File

We were seeing frequent file IO errors in relation to temporary files created during cooking (particularly when compiling shaders). Our findings for why this were happening were surprising. Here we present a clean way to fix the issues
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The Long and Winding Path of the Cook

The Long and Winding Path of the Cook

Long file path problems are commonplace when cooking with UE4. We took a look at it - and found that the engine was being too aggressive with its checks for whether or not a path really was too long
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Static Code Analysis With PVS-Studio (Part 5)

Static Code Analysis With PVS-Studio (Part 5)

The fifth part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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The Sadness of the Ignored Null Pointer

The Sadness of the Ignored Null Pointer

In this post we present an optimization coming from removing some pointless null pointer checks. The way that we found this was quite interesting
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Speeding Up The Time Limit Controls

Speeding Up The Time Limit Controls

When a process takes a long time to complete, it makes absolute sense to put some time limit checks in so that you're not starving other work. What you don't want to do, of course, is to have those checks slow your original task down further by any considerable amount - here, we found that exactly this was happening .. so we present a solution
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The Battle of the Lean and the Inlined Bone Functions

The Battle of the Lean and the Inlined Bone Functions

We took a look at the inlining of a certain part of the codebase and were shocked with what we found... we then went about improving it
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ToString() Or Not ToString()… Wait, What’s The Question?

ToString() Or Not ToString()… Wait, What’s The Question?

ToString() is one of the most commonly called functions in UE4 - certainly across the editor, the content cooker and such. Here we take a look at it and make it over twice as fast
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Tiny Code Fixes – Part 1

Tiny Code Fixes – Part 1

Here we present several small code fixes and improvements in a nice little package
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Package Versioning… How It Works… And An Optimization

Package Versioning… How It Works… And An Optimization

UE4's Package Versioning is a bit of a dark art for most.. here we try to remove some of the confusion around it - while, again, offering some improvements through optimization
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Portrait Of A Serialize Perf Killer

Portrait Of A Serialize Perf Killer

With performance critical editor and cooker code, it's well advised to consider performance when adding tests for rare errors. Here we take a look at this and show by, by considering the CPU pipeline and code cache, a simple change can yield a significant performance improvement without reducing stability
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Sweeping Up And Disassembling A Physics Macro

Sweeping Up And Disassembling A Physics Macro

Macros can often be useful to make certain programming tasks simpler - but they can also cause hidden performance headaches that might otherwise be avoided. Here we look at one of those - and how to improve it
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Static Code Analysis With PVS-Studio (Part 4)

Static Code Analysis With PVS-Studio (Part 4)

The fourth part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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When Are Shopping Lists A Waste of Time?

When Are Shopping Lists A Waste of Time?

We take a look at some list generating code with UE4 - and why it was completely pointless
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Using The Disassembler To Highlight Optimization Targets

Using The Disassembler To Highlight Optimization Targets

We use the debugger's disassembly view to look at FPaths::IsRelative() after it shows up in our profiling tests. Then we optimize it
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Static Code Analysis With PVS-Studio (Part 3)

Static Code Analysis With PVS-Studio (Part 3)

The third part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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The Cook, The Resave, His Garbage And Her Optimization

The Cook, The Resave, His Garbage And Her Optimization

We present here a way to improve cook times by reducing the frequency of garbage collection
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The Case Of The ExportHash String Monster

The Case Of The ExportHash String Monster

We found CreateExportHash() was showing up in profiling the cooker - so we optimized it. Our findings and changes are presented here
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Static Code Analysis With PVS-Studio (Part 2)

Static Code Analysis With PVS-Studio (Part 2)

The second part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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Patch Content Early – NOT At Runtime

Patch Content Early – NOT At Runtime

We present an optimization that removes a significant amount of memory churn from the animation code
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Static Code Analysis With PVS-Studio (Part 1)

The first part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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A Huge PhysX Memory Churn Reduction

A Huge PhysX Memory Churn Reduction

Here we implement a scratch buffer to reduce temporary memory churn passing through PhysX
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The Smallest, Coolest Optimization

The Smallest, Coolest Optimization

While profiling a game's runtime, we found that 40% of memory allocations were coming from a single function. The fix/optimization involves adding a single character
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The Clue In The Code Comments

The Clue In The Code Comments

We present a tiny little fix for a simple - but serious - coding error in the UE4 codebase
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