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Instruments is a performance-analysis and testing tool for iOS, iPadOS, watchOS, tvOS, and macOS apps.

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CPU Profiling with instruments fails to start
When trying to profile any process with the Instruments CPU Profiler I get this message: (Before run started) No allocated PMI record. Not sure what to do here. I tried other instruments like time profile and that works fine so not sure what to do here... Didn't find any people having similar issues when googling so I'm hoping someone here can help me out. Im using a m1 max 14 inch macbook pro with macOS 12.3 and instruments 13.0 (13A1030d)
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9.1k
Feb ’25
Instruments "Failed to split user provided arguments: working directory doesn't exist"
Trying to examine performance issues in Xcode Instruments using the Animation Hitches instrument in Xcode 16.0 beta 6 (16A5230g). When connected to my iPhone 15 Pro Max and I try to start a run with my app, it has an error “Failed to split user provided arguments: working directory doesn't exist” with timestamp “(Before Run Started)”. When running the app on an iOS simulator, the instrument runs fine—but I want to profile on a real device.
 Instruments > Settings, Recording Location set to Default and that directory does exist.
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921
Jan ’25
Instrument Recording Failure - CPU counter failed
Hi, I’m encountering an issue while using xctrace & instruments to profile an application on macOS. Specifically, when trying to record a trace using the CPU Profiler template, I get the following errors: Failed to start the recording: configureHardwareCounters: Failed set kpc configuration: Operation not permitted. Unexpected failure: Couriers have returned unexpectedly. macOS Version: 15.3.1 Chip: Apple M4 Pro Xcode Version: Xcode 16.2
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590
Mar ’25
Instruments - No PMI Record Found
Instruments CPU Profiler failed to start the profilable app (get-task-allow is set to true) with error "No PMI Record Found". Device is iPhone 13 Pro currently running iOS 17.0.3. Tried to profile in instruments shipped with Xcode 14.3.1, Xcode 15.0.1 and Xcode 15.1 Beta, same issue across. If it helps, I was able to successfully profile on iPhone X running iOS f16.7 using Xcode 14.2 instruments.
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2.5k
Nov ’24
[tvOS 18][SwiftUI] Severe ScrollView Lag after Update
Hello, I've upgraded both of my Apple TVs to tvOS 18. Since then, my app developed with SwiftUI has become almost unusable due to severe lag, particularly when scrolling in a LazyVStack. On the A1625 (Apple TV HD), the lag can last up to 20 seconds, while on the A2843 (Apple TV 4K, 3rd generation, Wi-Fi + Ethernet), it’s about one second. I can consistently reproduce the issue with this minimal example: @main struct MyApp: App { var body: some Scene { WindowGroup { ScrollView { LazyVStack { ForEach(0..<1000) { nb in Button("Item \(nb)") {} } } } } } } Using Instruments, I found that the hang is related to this call: 389.00 ms 71,4 % 6.00 ms +[_UIFocusRegionEvaluator __regionsByEvaluatingOcclusionsForBaseRegions:occludingRegions:baseRegionsCanOccludeEachOther:inSnapshot:] Unfortunately, I can't attach the Instruments trace directly here, but you can download it from this link: https://drive.google.com/file/d/1sEIwXhr7_ajjRHZevCIW6jNOlPjaeU6L/view?usp=sharing Important notes: The same screen, when written in UIKit, runs smoothly on both devices. After performing a factory reset on the older device, the performance issue disappeared. However, as you can imagine, I’m already receiving complaints from users who are understandably unwilling to reset their devices. Does anyone know of a workaround until this is addressed by Apple?
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1.1k
Oct ’24
Cannot run Animation Hitches Instrument
I'm trying to run the Instrument "Animation Hitches", but it fails immediately after starting on the iPhone. This happens on multiple projects, including a brand new project. I get the following errors: Timestamp | Message (Before Run Started) | Unexpected failure: Couriers have returned unexpectedly. (Before Run Started) | Failed to start the recording: Failed starting ktrace session. The issue also happens with the instruments App Launch, but not with any other that I tested. Is this a bug? Using Xcode Version 16.1, Mac Mini M1 Sequoia 15.1. Running project on iPhone 14 Pro iOS 18.1.
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1k
Dec ’24
How to collect macOS traces on customer machines with symbols for OS libs?
Our customers are large enterprises and we need to be able to collect traces on our customers' endpoints in support cases. Especially critical are performance problems. So far we've instructed our customers to use ktrace: sudo ktrace artrace -p appname --type=profile We would then open this trace in Instruments with the CPU profile and load our own symbols. The problem is, that symbols for system libraries are missing. In one instance we see that all of the high load is coming from a syscall made by libpcap. But all symbols other than our own are missing. How can we collect traces which include those symbols? I tried to use ktrace symbolicate in tests where I recorded a trace and then used ktrace symbolicate to collect system lib symbols, but it fails for most libraries, including libpcap and the syscalls. This is somewhat surprising, because dyld_info -exports /usr/lib/libpcap.A.dylib is able to print the symbols including offsets. So what is the recommended workflow for this scenario? Installing Xcode is of course not an option on a customer machine, especially not in an enterprise scenario.
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Dec ’24
On-device hang detection with threshold lower than 250 ms
There is a WWDC session about this cool instrument to detect hangs on-device: https://developer.apple.com/videos/play/wwdc2022/10082/ I very like this tool; it's handy and gives useful stack traces, but the threshold of 250 ms is practically too high to use in a testing environment. It would be better if there was an option like 100 ms or something like that. I think most of the people can see the scrolling hang with a duration of 100-250 ms, and it would be cool to detect such hangs with this instrument. Is there a way to set a lower threshold, or can Apple consider adding such a threshold? Thank you!
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Sep ’24
Help me to understand sending push to Wallet card
Good afternoon) I am doing one of the test projects to create a PKPASS and a server to update this file on the device, as well as sending PUSH-a. APN service is used with JWT Bearer token. The server is written in Java Springboot. We try to send push notification, pkpass update happens, response from APN 200 OK. But there is no notification, can you please tell me why this is happening? I am also sending you a sample request: curl -v -X POST -H "apns-push-type: alert" -H "apns-id: 5af474c5-a212-42f3-9f99-70a9e587e1e2" -H "apns-topic: pas.example225" -H "apns-expiration: 0" -H "authorization: bearer eyJraWQiOiJGQ0pQVFFMV1ZNIiwiYWxnIjoiRVMyNTYifQ.eyJpc3MiOiI2N0ZGUTY1TEQzIiwiaWF0IjoxNzMwMzY3NzQ4fQ.FGXSLCR6mxkQyi7bNliZKZbVdN3m0xQzFSMUDRFU4aAYIgsgflk5MDEkS9k5riMHp10wpr80b20uq9cuPnoQqw" --data '{"aps":{"alert":{"title":"title","subtitle":"subtitle","body":"body"}}}' \ P.S. I checked JWT on the page: https://icloud.developer.apple.com JWT was built correctly. Thank you for your reply) Translated with DeepL.com (free version)
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816
Nov ’24
Not seeing signposts when profiling a unit test (Xcode 16.1)
While I was recently profiling some code from a Swift library, I noticed that XCTest added in signposts for the measurement tests, which I found really helpful to "home in" on the code I wanted to profile digging around in the stack trace. I tried to add my own signposts to provide just a bit of my own markers in there, but while it compiles and profiles equivalently, the signposts just aren't showing up. This is with Xcode 16.1, macOS Sequoia (15.1) and a swift library, using XCTest and profiling within one of the unit tests. Is there something in this sequence that doesn't allow the library to set up signposts and have instruments collect them? The flow I'm using: import os let subsystem = "MyLibrary" class MyClass { let logger: Logger = .init(subsystem: subsystem, category: "fastloop") let signposter: OSSignposter init() { signposter = OSSignposter(logger: logger) } func goFast() { let signpostId = signposter.makeSignpostID() let state = signposter.beginInterval("tick", id: signpostId) // ... do a bunch of work here - all synchronous signposter.endInterval("tick", state) } } Is there something I'm doing incorrectly in using this API, or not enabling to allow those signposts to be collected by the profiler? I do see the signposts that XCTests injects into the system, just not any of the ones I'm creating.
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723
Nov ’24
Identifying memory leaks
I'm having an issue with my swiftui macOS application where it is continually consuming more memory over time and after a couple of hours will grind to a halt. I've watched a few videos now on how to use Xcode Memory Graph and Instruments to identify the source of a leak (I assume it is a leak). These videos all provide very obvious issues as examples but mine seems more elusive and I don't know how to identify which part of my code is the cause of the issue. After running instruments I see the following but the leaked objects are not always consistent: Xcode Memory Graph shows NSSet as the culprit which is shown under CoreFoundation (not my App). I really am a beginner here and because it's not showing me somewhere in my app that I can go and investigate I'm really stuck.
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2.0k
Dec ’24
PacketLogger doesn't capture logs for iOS devices.
I'm unable to capture Bluetooth logs via PacketLogger from my iPhone 11 (iOS 18.2) and iPad Pro (iPadOS 17.5.1) with Mac mini M2 macOS 15.2 (24C101). I've installed Bluetooth profile on both devices, restarted multiple times connected to the computer, it shows device as online, however PacketLogger captures nothing at all. For test I've installed profile on macOS and PacketLogger captures everything as it should. I saw some posts here from earlier this year, that people were having similar problems with PacketLogger. Please suggest a solution or confirm that it is a known bug.
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1k
Dec ’24
How to symbolicate kernel callstacks (or what is kernel.release.t6020)?
Hi everyone, (I am running on an M2 MacBook Pro 14 inch with 96 GB of memory) I've been profiling with Instruments to find out why program suddenly goes from full CPU usage (all of my threads active and all cores working) to about 33% CPU usage. An Instruments system trace is showing me a massive performance cliff where I suddenly get taken off the performance cores and only run on efficiency cores. The performance cores are then occupied by "kernel.release.t6020". What is this thing? I have kernel callstacks enabled but I only get the instruction pointer and have no symbols for any of those callstacks. I'm accustomed to Windows development where kernel symbols are available so you can see deeply into the kernel to know why you're spending time there (for example, semaphore wait or thread scheduling). Is there a way for me to get a similar level of information or kernel symbols so I can see what the kernel is doing? Around the time I observe the performance cliff, I also noticed in the narrative view some of the preemptions are done "because thread was balanced off CPU i (P Core) to optimize the system's CPU performance". What does this mean? Have I begun to hit some sort of thermal limit? Here are some example screenshots of what I am seeing in Instruments:
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528
Jan ’25
XCTestCase Async Setup Function Always Causes Leak in Instruments
I'm developing a library and using XCTest for unit tests. While trying to profile the test suite, I noticed that Instruments seems to report a leak every single time the async throwing setup function is called, no matter what. For example, This will report a leak: final class LeakTests: XCTestCase { override func setUp() async throws { try await super.setUp() } func testLeak() async throws { try await Task.sleep(nanoseconds: 5_000_000_000) } } This will not report a leak: final class LeakTests: XCTestCase { // override func setUp() async throws { // try await super.setUp() // } func testLeak() async throws { try await Task.sleep(nanoseconds: 5_000_000_000) } } Any ideas on why this might be happening, or should I just file a bug report? It makes it quite difficult to use the leak detection for unit tests, as it shows hundreds of leaks when the whole suite is ran.
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459
Jan ’25