Dart Analyzer very slow/stuck #55281
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lrhn
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area-analyzer
keertip
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type-performance
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@DanTup , do you see this? Have there been more reports of this kind? |
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/ cc @bwilkerson |
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I've not seen any other reports like this. 100% CPU certainly does not look healthy if it's persisting for a long period after initial analysis. @JonasJW a few questions:
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We were having the same issue and using the Removing it completely seems to have solved the issue for us, are you using it too, and can you try to remove it to confirm it comes from there if you are ? |
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/cc @scheglov |
keertip
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@DanTup Thanks for the response and sorry for the late reply. code --status output:To be honest, I'm not quite sure what you mean by your question about symlinks or how I can find out. Yes, this issue seems to have started just recently without making any noticeable changes such as updating SDKs, installing extensions, etc. Here are further screenshots, I hope this is the server timing page you meant.
If you have any recommendations what I can try to fix this issue, I'm happy to try that. As mentioned, I have already tried uninstalling Flutter/Dart, VSCode, etc. at the moment I don't know what else I could try. |
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For us updating |
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@JonasJW thanks - the page I meant was the one marked "Timing" on the left. Can you also confirm whether you're using any analyzer plugins? A few comments above suggest You should be able to check for symlinks by running |
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@DanTup thanks for the clarification! I don't use When I run Is that anything out of the ordinary? Here the screenshots of the "Timing" page:
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That one doesn't look like a problem, but are there any that point back up the tree (eg. creating cycles or including other large parts of the disk in the the path)? It may be useful to enable the analyzer instrumentation log (this file can get very large - be sure to turn it off afterwards) and reproduce the issue, and see if there is anything in the log file that looks out of place while this happens (for example exceptions, or paths you would not expect to be analyzed with this project open being analyzed). You mentioned this only happens on large projects - are any of them public projects that I could test with (or that sharing logs from would not include anything sensitive)? |
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Hi @DanTup, I apologize for taking so long to respond. I still have this issue and it's really slowing down my development process.
Here are a few symlinks, some point up but it doesn't appear to me that they would create a cycle
In total there are over 550 symlinks. Does any of this sound problematic? I also tried the analyzer instrumentation logs but I can't really find anything that appears out of place. However, this document seems to log all kinds of stuff and I'm not sure how to analyze it or what to look for. Yes, unfortunately, this project is private and can't be shared. I could probably share the analyzer instrumentation logs privately with you, if that would help. I recently tested this project on a windows laptop and the issue occurs as well. (Thus, I think completely reinstalling my mac won't even help fix it). These issues don't appear on new Flutter projects. Maybe I could try to download a big public project and see if I have problems with other bigger projects as well? If not it must be something specific with my project but I'm clueless about where the issue could be. |
Nothing above looks like an issue to me - the issue would be if the link points further up the tree so that walking the tree could cause endless cycles.
The most useful thing would be knowing what's being logged during the periods where performance is bad. So if the bad performance is during startup, it would be the start of the logs (until the first
I can't accept anything confidential (instrumentation logs can contain contents of opened files and paths/errors for other files in the workspace), but if you're able to reproduce this on a copy of the project with anything confidential removed (and perhaps only a single test file open), you might be able to get a log that doesn't contain anything confidential you can share. Something I forgot to ask earlier - can you confirm whether you have this option ticked in the VS Code (User or Workspace) settings?
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Understood, I will go back to the logs and look for these progress events. If I have something to share I will follow up on it here. The |
FWIW, my recommendation would be to not use that setting (and I should update the text). Although it sounds better for large projects, it was really added for a fairly specific case (command line editors that would provide the current working directory - which may be the user home dir - as the workspace folder). While the server will start up faster for very large workspaces, opening and closing files from different projects will trigger re-creating the analysis roots which can trigger "initial" analysis for those projects. It's beneficial if you're opening a folder that contains 100 projects and maybe only opening files from a handful, but if you're jumping between a large portion of the projects in the workspace, it's probably worse overall. |
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@JonasJW what is your current experience with analysis performance? Are you still experiencing this weird behavior? |
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@mraleph yes, I'm still experiencing performance issues |
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@JonasJW are you able to reproduce this issue with any public projects? It might be easier to narrow down with an instrumentation log, but that log will contain parts of source code from the open projects. If it only occurs with this one specific internal project, is it possible to make a copy of it and see if you can narrow down what causes it (for example if it's made up of many packages, can you remove some of them to narrow down if it's caused by a specific package/set of packages)? Do you also know if this issue occurs when typing in any file, or just some subset? This issue could be similar to #56307 which may be caused by the number of files that need to be reanalyzed as you modify a file (see #56307 (comment) and #56307 (comment)). |
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Maybe a related issue |
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We have a pretty large project (internal, 200k lines), and this issue is pretty hard on productivity. The worst of it comes from typing new class properties. The analyzer will get stuck on these for up to 20-30 seconds. Here's my 
(The top consumer seems to be the Android Emulator, which is probably fine) Here's the Dart process (if relevant): Anything else I can do to help debug this issue? |
If the alternative is to have all of features/modules be separate packages but not part of a workspace, then yes. The benefit of a workspace is that there is a single version solve for all of the packages in the workspace, which means that it's safe for the analyzer to build the element model for each third-party package once and share them across all of the packages. Without that guarantee of a single version solve the analyzer has to build the element model for each third-party package once for every package that has a dependency on it. If the alternative is to have a single large package with all of the code in each of the separate packages, then no, splitting it into separate packages in a workspace won't change the performance of the analyzer. On the other hand, if splitting the code into multiple packages would help to reduce the number of circular dependencies between pieces of the code, then the reduction in circularities would improve the performance of the analyzer. |
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We've been experiencing this problem for a while now. We are currently on |
It effectively analyses everything in the cycle as if it were in a single library. |
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I have this problem since upgrading to Flutter |
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Same issue for me. After upgrading from Flutter version |
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Everybody reporting perceived regression in 3.29 please add as much information as you can to #60335 (comment) |
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I have the same issue. Previously, I had a few barrel files, but after removing them, the performance is still just as slow. In my opinion, could this be related to the generated files? In my project, I’m only using Flutter: |
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After updating the plugin I still experience the same slowness. |
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@luis901101 not surprising because I don't think we know anything about what "slowness" is nor did we actually fix anything anywhere. If you can attach information described here. Then at least we can try to categorize the issue you are experiencing. |
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@mraleph I already did it 3 weeks ago: #55281 (comment) |
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Maybe an update is in order. Based on the reports received so far I've identifier:
I also discovered a bug in the flutter intellij plugin (flutter/flutter-intellij#7980) which can make the analyzer become unresponsive for a while when opening a file. None of the fixes have been released in stable yet, and I can't claim that they will definitely fix the issues you're seeing - but at least it's something. And again: If you are experiencing issues please upload reports as described in #55281 (comment) - it actually helps :) |
You are right. I downgraded to version 3.27.4 and the slowness went away. |
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For folks experiencing issues with 3.29, please see this comment. TLDR: if you are experiencing issues with Flutter 3.29 / Dart 3.7 (which you did not experience with earlier versions) and you are willing to test a fix for us leave a comment on the linked issue with your platform e.g. (Windows, Mac (X64), Mac (Apple Silicon), etc) and I will provide a custom Dart 3.7 SDK build which you can test and see if it resolves 3.29 issues. |
I'll like to test, Mac Apple Silicon over here. |
Instructions here. Notice this is not supposed to help with some random slowness. We are only looking to validate if this fixes regression in Flutter 3.29 / Dart 3.7. If you just experience generic slowness, which is the same in 3.29 and previous releases - then it makes no sense for you to test it. Only test it if your experience has regressed in 3.29 and you have better performance with previous stable releases. |
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I've got this problem in spades. It's not just that it's slow; it's that it's broken, too. If I see a red underline and hover over it, it takes 5–10 seconds for a popup to appear if one does (only works about half the time). Usually, it says nothing. When it does appear, it's often wrong.
I have previously relied on the popup that appears when hovering to add import statements. That's just entirely stopped working. The plugin has always seemed like the red-headed stepchild of Flutter efforts. It's always been slow and a bit flakey. But why is it getting worse? |
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@gisborne: are you on Flutter 3.29? If so, would you be willing to try the custom SDK @mraleph rolled? (See instructions in #60335 (comment).) |
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Installed the custom SDK. It's still not working properly. Time was when this would have offered to make the function for me.
Time also was when:
would also offer to change things to an expression body. |
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Thanks for checking! The lack of an assist offering to create the function could be a different issue, but I wonder, is the popup still taking a long time to appear? |
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The popup is still taking a long time to appear. But then, it always did take a long time. It's about as slow now on my M4 Pro as it was on my M1. |
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In my case after using the dart-sdk with the fix from here it has worked as expected, syntax highlighting, formatting, auto completion, auto imports all very good. This is a test just right now: Analysis Driver Timings:(name: <scheduler>, count: 0, elapsed: 0:00:00.000000, elapsedSelf: -0:00:12.004791)
(name: getUnitElement, count: 284754, elapsed: 0:00:03.113551, elapsedSelf: 0:00:01.157006)
(name: libraryContext, count: 284754, elapsed: 0:00:01.956545, elapsedSelf: 0:00:01.501911)(bytesGet: 24121433, bytesPut: 186090, cycleCount: 1727, libraryCount: 10678, libraryLoadCount: 10597)
(name: libraryCycle, count: 284754, elapsed: 0:00:00.116997, elapsedSelf: 0:00:00.116997)
(name: link, count: 76, elapsed: 0:00:00.337637, elapsedSelf: 0:00:00.001427)
(name: LibraryBuilder.build, count: 76, elapsed: 0:00:00.031726, elapsedSelf: 0:00:00.001067)
(name: libraryFile, count: 81, elapsed: 0:00:00.030659, elapsedSelf: 0:00:00.000253)
(name: parseCode, count: 81, elapsed: 0:00:00.030406, elapsedSelf: 0:00:00.030406)(length: 224984)
(name: buildOutlines, count: 76, elapsed: 0:00:00.273136, elapsedSelf: 0:00:00.248209)
(name: computeLibraryScopes, count: 76, elapsed: 0:00:00.023050, elapsedSelf: 0:00:00.015749)
(name: buildMacroApplier, count: 76, elapsed: 0:00:00.007007, elapsedSelf: 0:00:00.007007)
(name: executeMacroTypesPhase, count: 76, elapsed: 0:00:00.000294, elapsedSelf: 0:00:00.000294)
(name: executeMacroDeclarationsPhase, count: 76, elapsed: 0:00:00.000685, elapsedSelf: 0:00:00.000685)
(name: executeMacroDefinitionsPhase, count: 76, elapsed: 0:00:00.000699, elapsedSelf: 0:00:00.000699)
(name: mergeMacroAugmentations, count: 76, elapsed: 0:00:00.000493, elapsedSelf: 0:00:00.000357)
(name: buildAugmentationLibraryCode, count: 81, elapsed: 0:00:00.000136, elapsedSelf: 0:00:00.000136)
(name: writeLibraries, count: 76, elapsed: 0:00:00.031348, elapsedSelf: 0:00:00.031348)(length: 186090)
(name: analyzeFile, count: 322, elapsed: 0:00:08.891240, elapsedSelf: 0:00:04.271575)
(name: libraryContext, count: 322, elapsed: 0:00:04.619665, elapsedSelf: 0:00:00.209948)(bytesGet: 64626977, bytesPut: 6333038, cycleCount: 59, libraryCount: 30749, libraryLoadCount: 28004)
(name: libraryCycle, count: 322, elapsed: 0:00:00.241002, elapsedSelf: 0:00:00.241002)
(name: link, count: 17, elapsed: 0:00:04.168715, elapsedSelf: 0:00:00.000987)
(name: LibraryBuilder.build, count: 17, elapsed: 0:00:00.782481, elapsedSelf: 0:00:00.021290)
(name: libraryFile, count: 2745, elapsed: 0:00:00.761191, elapsedSelf: 0:00:00.001325)
(name: parseCode, count: 2745, elapsed: 0:00:00.759866, elapsedSelf: 0:00:00.759866)(length: 11701506)
(name: buildOutlines, count: 17, elapsed: 0:00:03.264415, elapsedSelf: 0:00:02.666760)
(name: computeLibraryScopes, count: 17, elapsed: 0:00:00.593127, elapsedSelf: 0:00:00.486603)
(name: buildMacroApplier, count: 17, elapsed: 0:00:00.104714, elapsedSelf: 0:00:00.104714)
(name: executeMacroTypesPhase, count: 17, elapsed: 0:00:00.001810, elapsedSelf: 0:00:00.001810)
(name: executeMacroDeclarationsPhase, count: 17, elapsed: 0:00:00.001487, elapsedSelf: 0:00:00.001487)
(name: executeMacroDefinitionsPhase, count: 17, elapsed: 0:00:00.001338, elapsedSelf: 0:00:00.001338)
(name: mergeMacroAugmentations, count: 17, elapsed: 0:00:00.001703, elapsedSelf: 0:00:00.001103)
(name: buildAugmentationLibraryCode, count: 2745, elapsed: 0:00:00.000600, elapsedSelf: 0:00:00.000600)
(name: writeLibraries, count: 17, elapsed: 0:00:00.120832, elapsedSelf: 0:00:00.120832)(length: 6333038)
Video demo from Android StudioScreen.Recording.2025-04-02.at.12.01.06.movAnalysis Reportdart_analyzer_diagnostics_report.json And compare with this previous test I shared before: #55281 (comment) |
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One request (to @luis901101 specifically but also to everybody else): please keep any Flutter 3.29 / Dart 3.7 related content in the 3.29 issue. If you are relatively happy with analyzer performance but experienced problem with Flutter 3.29 / Dart 3.7 - go to #60335. We are already piling too many things into this issue and it is becoming a kitchen sink. Everything that has clear root cause - we fork discussion into a specific issue and keep it there. Only generic reports (which have not been triaged to a specific root cause) should remain here. Thank you for understanding. |
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@mraleph should I move my last comment to the other issue? |
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@luis901101 I think it is okay to keep it here. |
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I've been using the test version and if anything, it's slower. I fixed a minor type issue over a minute ago, and I'm still seeing the red squiggle shrapnel and the Dart Analysis window is still showing the error. Sometimes, it gets stuck and never notices that I've fixed something. I find myself restarting analysis every five minutes or so.
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I'm really tired of having to work out relative paths for writing manual imports. Automatic imports does not, afaict, work at all, ever for me. |
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@gisborne Is the problem you're experience a regression in Flutter 3.29, or is this an issue you've been seeing since before 3.29? Just trying to establish how many performance issues we might have. Also, could you open the server diagnostics pages, select the "Collect Report" tab, generate a report and send it to us (after reviewing the data to ensure that we didn't accidentally include any personal or confidential information in it)? Thanks. |
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I've been having such problems for some time. A year, maybe? Happy to do a screen share or something while we do diagnostic things, if that would help. hmu To be clear: it has gotten significantly worse now. The analyzer is slowing me down significantly — particularly when it doesn't offer to write import statements for me. |
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Are you using workspace resolution by any chance? I thought it was neat and decided to use it. But things got unusably slow. It would analyse for minutes and then after every small change it would analyse again. I press 2 keys and there it goes again. Memory usage was at 13.8 Gb. I just reverted back and now it is at 3.4Gb when I load my big workspace. It still needs time (a minute or so) to analyse after I open my workspace but not nearly as long and it stopped needing to analyse again and again after ever small change. |
and others
Dart & Flutter has suddenly become unusable slow in VSCode. Intellisense won't load within 30+ seconds, syntax highlighting won't update, jumping to code definitions loads infinitely, etc.
This seems to be especially the case on bigger projects, on a newly created project it works fine. I tried switching to Android Studio which seems to behave similarly (maybe a little better).
I tried uninstalling all extensions, even completely removing VSCode with any data stored and reinstalling it. As soon as I install the Dart extension, it is unusable. I also tried setting the following settings:
I'm on macOS 14.4, VSCode Version 1.87.2 (Universal),
In the Activity Monitor, there is the
dart:analysis_server.dart.snapshotprocess running with around 1 GB of used memory. I'm not sure if this is normal.Here is a screenshot from the Dart Analyzer (which I'm also having trouble opening)
dart infooutput:General info
Project info
Process info
Any recommendations on how I could possible fix this would be very welcome!
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