Rider freezes UI very often when combined with NCrunch

Thanks, I'll have a look around and will get back to you.

Some more questions:

- Do you have a lot of editor windows open when the freezes are happening? Does closing all but the one editor window have an effect on the problem?
- Is there any length of time that you're able to use the IDE after a fresh start before you notice the issue appearing?

Remco wrote:- Do you have a lot of editor windows open when the freezes are happening? Does closing all but the one editor window have an effect on the problem?

Windows? No. Tabs per instance in its single window? Yeah, quite a few, I'd say around 30-50 open file tabs at any given time.

I started the day by closing every instance, invalidating Rider's caches, and opening three solutions (medium to large size), one of which contains ~600 tests. Things felt smooth for a while, but it didn't take long before it became somewhat sluggish, freezing every 5 minutes or so for about 3–5 seconds. I might be biased, but whenever the freezes started, I'd close every tab in the instance I was working in. It felt like it helped — the freezes would still occur, but they seemed to take a bit longer to come back.

Remco wrote:- Is there any length of time that you're able to use the IDE after a fresh start before you notice the issue appearing?

Iit really depends and feels somewhat random. Today it took about 1–2 hours before the freezing returned.

Would you be interested in trying the build below to see if it helps with the problem? This build contains a few optimisations to reduce memory traffic, particularly around editor window integration. It's a blind stab, but worth trying.

NCrunch_Rider_5.21.0.7.7z
NCrunch_Rider_5.21.0.7.zip

Remco wrote:Would you be interested in trying the build below to see if it helps with the problem? This build contains a few optimisations to reduce memory traffic, particularly around editor window integration. It's a blind stab, but worth trying.

NCrunch_Rider_5.21.0.7.7z
NCrunch_Rider_5.21.0.7.zip

When I try to install from disk I get:
"Plugin 'NCrunch' (version '5.21.0.7') is not compatible with the current version of the IDE, because it requires build 261.21525 or newer but the current build is RD-253.31033.136"

mullerwashere wrote:
When I try to install from disk I get:
"Plugin 'NCrunch' (version '5.21.0.7') is not compatible with the current version of the IDE, because it requires build 261.21525 or newer but the current build is RD-253.31033.136"

Ahh, sorry, I should have mentioned this. I've moved the Rider plugin up to the newer version, because it's set to drop soon. To try this build, you'll need to use the 2026.1 EAP build. This should be a free download from the JB site.

I also have this since the "later" Rider Versions (not EAP). Sometimes Rider freezes when opening the Solution and the NCrunch Test Runner Tool Windows is active. Or when i switch to it.
(had the latest NCrunch Forum Version installed). Was good a while, but godd worse in the last weeks. Maybe an Rider Update was not good for NCrunch.

Will upgrade die EAP and give this Version a try.

@Remco, just sent you my findings via the contact form. Hopefully it can help you.

Thanks for sharing this. It was very useful!

Here's my next try:
NCrunch_Rider_5.21.0.8.7z
NCrunch_Rider_5.21.0.8.zip

Remco wrote:Thanks for sharing this. It was very useful!

Here's my next try:
NCrunch_Rider_5.21.0.8.7z
NCrunch_Rider_5.21.0.8.zip

Hey, no luck, pretty bad freezes today, didn't take long to start happening. Sent you my findings in the contact form.

Ok, here is attempt #3

NCrunch_Rider_5.21.0.9.7z
NCrunch_Rider_5.21.0.9.zip

Unfortunately, I am experiencing the freeze problem again with the latest version of NCrunch 5.21.0.10 in combination with Rider 2026.1.0.1. So, when I click on another screen/window, it unfreezes again.

I have send in the contact form the Rider logs

Can also say the freezes still happen. An NCrunch seems to be at least involved.
When I kill the nCrunch.Rider.EngineHost when the freeze is gone.

Does disabling the engine get rid of the freezes after they start happening?

Is there any correlation between the freezes and number of editor windows you have open?

Another question: Does recovery from the freeze happen on its own? Or do you absolutely need to click on another window? I'm wondering if it's a performance issue or some kind of temporary crash.

So this issue finally started happening for me with relative consistency, or at least, it started showing up when it felt like it.

I've been trying to analyse it for a few weeks now, and I'm presently working on a theory that it's being caused by NCrunch's CPU affinity handling. As with VS, NCrunch changes the processor affinity mask for the running Rider process (both the Intellij frontend and the ReSharper backend) so that it runs on different CPU cores to the NCrunch engine. The config wizard does this automatically and you have the ability to micromanage the distribution through the CPU core settings.

Under VS doing this is fairly harmless as long as the IDE has enough resources to do its work, though under Rider, when I have the IDE constrained, the freezes appear. If I set the CPU cores for Rider to be all available cores, the freezes so far haven't been happening.

So if you're experiencing this issue, make sure you have Rider set to use ALL cores on your system via NCrunch's config settings, then restart the IDE. I'm eager to hear if this solves the problem for you. If so, I'll modify the next build to make the CPU core settings ineffective for Rider sessions, since they then clearly aren't worth it.

Ok, will try it.

Current Configuration (since I've got the new Laptop about 18 Month Ago)

Cores for IDE: 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19
Cores for NCrunch: 20,21,22,23,24,25,26,27

But I did not recollect an Issue in the last Weeks (but also I'm on the 2026.2 EAP Bandwagon). On the other side, the brain also ignores stuff ;)

After I cleared the Cores for the IDE. The effective value is now: 0,1,2,3,4,5,6,7,8,9,10,11,12,13
Less then before ;)

But in the last weeks I improved my excluding list for IDE Stuff from the Windows Defender Scan. That may be an a alternative reason I don't recall freezing Issue.

Try setting the cores for the IDE to EVERY core on your system (i.e 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27). It should be safe to overlap with NCrunch cores. The core splitting system was originally designed back when we were using quad-core machines. I doubt we'll see any difference on modern hardware.

If I'm right, you'll never freeze like this.

My theory is that something in the IDE is trying to allocate work onto specific cores, then is stalling when our core mask prevents it. The selected core might vary between sessions, which could explain why the problem seems so bad sometimes then at other times it never shows.

BTW 28 cores is pretty impressive for a laptop. That's some nice hardware.

Ok, did that.

28 Cores... yeah,in theory fine. https://www.intel.com/content/www/us/en/products/sku/232161/intel-core-i713850hx-processor-30m-cache-up-to-5-30-ghz/specifications.html

Also in a beefy HP Laptop with better cooling.... but still no good. The plan was assign the effiency core to NCrunch.

Sounds like a plane taking off when working, it throttles after around 2 minutes of full load.

Without a power brick it constanlty complaing that i should plug in to get some speed out of it.

A beefy Desktop with that kind of Cores and excelent cooling i would prefer… but who pays say what it payed for.

On the other hand, at least we are getting Hardware were you can work on. Some companies are cheaping out.