A Mystery To Solve: Memory Leaks While Files Download?

I did not have tons of money when I built this PC, so currently my install of Windows occupies as little as 100gb, with around 8-15gb of free space at any given time. The drive itself is 500gb, but the rest of it is taken up by older data that's lived on the same partition as my C:\ for many, many years. (mostly its game development software and art resources, but it's also perpetually nearly full).

I say this to set up the first instance of when I noticed this problem occurring: when downloading Forza Horizon 4 from the Windows Store, it got to around 80 or 90% downloaded and then my whole system ground to a halt as the pagefile filled up. I tried my best to diagnose, but it got slower, and slower, and slower, until I eventually got it to reboot and everything went back to normal. Forza finished downloading and everything was fine.

A few weeks ago, something similar happened, this time with Sea of Thieves. This time, I watched C:\ fill up as Sea of Thieves downloaded, going from 11gb free to just a few hundred megabytes. Again, the system began to grind to a halt, but I caught it early, rebooted, and everything was fine. At the time, I thought maybe the Windows Store app was probably storing data temporarily on C:\ and as storage was gobbled up, the system struggled to maintain function.

Today, I installed a new HDD. Not on C:\, no. Remember, I said that 500gb HDD was two partitions -- Windows and game development tools. A few years ago, I bought a second HDD, a 2tb Western Digital Black, to store Steam games and video capture for my Youtube channel (D:\ drive). That drive was approaching five years old, so I caught a deal on Western Digital Red drives and replaced it with a 4tb version. The slower speed worries me, but prices on platter HDDs have been weird for a while (that's a different topic).

Having more room to breathe now, I decided to put it through its paces. I queued up some of the larger game downloads in Steam -- notably Metal Gear Rising (26gb) and Sunset Overdrive (29gb) in particular. And, after about an hour, I noticed the telltale signs of my system beginning to slow down, just like when I was downloading games from the Windows Store.

Unlike with the Windows Store, C:\ was untouched. It remained at a "comfortable" 10gb free. Nothing was constraining the actual operating system files, but my system was beginning to buckle under an unseen force anyway.

Popping open the Task Manager, Windows was claiming Firefox was the culprit, showing its memory usage in red, but it was only taking up 200mb of RAM, which is a pathetic amount compared to the gigabytes it often burns through. It also said Steam and Discord were to blame, but they were taking up less than half of Firefox's figure -- around 50mb a piece. I closed Firefox and eventually Discord, and while that helped a little, the problem was still slowly getting worse the more Steam was allowed to download.

Opening the resource monitor, Disk activity was all over the place. Indeed, Steam was having trouble maintaining its download, just like what had happened to Forza Horizon 4 in the Windows Store. Steam's ability to access the disk was being rated in kilobytes per second, despite topping out at 17mb/s not even one hour earlier. The pagefile for D:\ (my steam drive) was also coming up a lot for high activity.

Under Memory, the Resource Monitor was saying "Memory Compression" (the service that manages the page file) was also going crazy, with the bar graph totally maxed out. Unfortunately, I don't know how to read this section quite well enough -- I'm mainly a bit fuzzy on what "hard faults" mean, but Memory Compression by itself was over 120 hard faults per second.

Back in the Task Manager, it was claiming 99% memory usage, which was easy enough for me to understand, even though everything listed was actually taking up criminally little memory.

I'd figure maybe it was a memory leak, but I guess I'm also still not sure what those are, either. I understand the general idea (something gets stuck in memory and never gets freed for other software) but I'm not entirely clear on the effects. My main point of reference for a memory leak was Windows 98, where the Active Desktop would die, or your icons would get scrambled. I don't know what a modern one looks like.

So I rebooted before it got too much worse. Windows loaded back up to a much healthier 30% memory usage and resumed downloading Sunset Overdrive. Near as I could figure, maybe it was a problem caused by Firefox -- in all three scenarios, Firefox was the program I noticed the problem in first. Pages would have difficulty scrolling, text entry would become sluggish, videos would stutter.

But after Windows rebooted, it graciously reopened the task manager and resource monitor for me, as I'd left them open when I started the reboot. So I sat there on an empty desktop, with nothing more than Steam and Discord open, as I watched Windows' memory usage begin to climb while Sunset Overdrive downloaded its last third.

35% memory usage... 40%... 45%...

Steam itself did not appear to grow in memory usage during this time. It hung around 250mb, as did Discord, but something in the system was slowly eating memory. It hit 50% memory when Sunset Overdrive finished downloading, and the moment it did, memory usage rested at 49% and stayed there.

I'd just like to know what's going on here, what normal operation is, and how to prevent these problems in the future. I'm a mid-range user, I understand some of what's going on, but I don't understand all of it.

I don't think it can be blamed on the new HDD, I don't think it can be blamed on the Windows Store, and even though Firefox is a constant in all of these scenarios, I pretty much always have Firefox open all day anyway, so of course it's going to be running when anything goes wrong.

If anyone can shed some light on this, I'd love to hear it.

 

My thoughts are that you need much more free space on the operating system partition.
When downloading, copying, or anything involving moving data, my understanding is that it has to write t the hard drive first,and needs space to do that- I feel the 10gb free is far too little.
If there is nothing you can move from you C drive to a spare hard drive, you will need to extend that C partition- Then you say the second partition is also pretty full- so you need to create more space.
My way of solving this would be to transfer as much data from the second partition to a spare hard drive, and try to lose about 100gb or, more, from it
-
BUT, when this full, I have found that it can take a long time, as you need to remove small files at a time ,until it starts to move those files a little quicker- Experience tells me that you need to be patient, and not try to move large files until you get to , say 50 gb free.
The files should then be easier to move .
When you clear space on the second partition,you can use Windows partition manager to shrink the second partition, to free up space , so that you can extend the C drive to take in that extra space needed.
Try to understand what I have said, and come back with any progress, or, problem.

 

I think I've tracked down the culprit.

My motherboard came with a piece of software its drivers disc installed called "Killer Network." It's supposed to help prioritize gaming traffic on your system, so things like Windows updates or whatever don't interrupt multiplayer sessions. I had a friend complain about it in the past, but I'd never had any trouble with it, so I figured maybe it was better now and I left it alone.

I've had to reboot my system three times today because the website Giantbomb was having a "free trial" month for their premium subscription and I was downloading a lot of their paid web shows. This time, I was using the uGet download manager, and just like in my original post, the more things downloaded, the more memory would slowly disappear without a trace. Nothing in the Task Manager or Resource Monitor would visibly increase in memory usage, but just the same, memory was being gobbled up by something.

And then it dawned on me: if memory is leaking just because something is downloading, regardless of what's downloading it or where it's being downloaded from, I have a piece of software running that monitors and controls network traffic and could be effecting things.

Almost 30 minutes ago I disabled both the Killer Network software and service and the problem instantly vanished. My memory usage hasn't budged, even though I downloaded another 10 videos from Giantbomb.

I'm going to update the first post's tags to include Killer Network to make this post easier to find.