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Chris Goddard

10/14/2020, 12:38 PM
Hey there - not sure if this belongs here or in community but I'm using Prefect Cloud and I often find that the dashboard becomes unresponsive when the page is left idle for a while. Refreshing doesn't work (I think maybe the refresh is overridden via history api? not sure) - I often have to close and open the page again. Anyway, it's not a big deal but as I often have the dashboard page open in the background so I can periodically check on it - which I feel like is probably fairly common. This is on Windows/Chrome/86.0.4240.75.
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Greg Roche

10/14/2020, 12:43 PM
I have also noticed exactly this issue, with Prefect Server running on an EC2 instance. +1 to hoping it is resolved.
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Raphaël Riel

10/14/2020, 12:46 PM
Same here. I have to Hard-Refresh the Page for the UI to work again. MacOS + Chrome 86
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Chris Goddard

10/14/2020, 12:46 PM
ok great - glad i'm not crazy 😂
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Raphaël Riel

10/14/2020, 12:47 PM
And this kind of unresponsiveness is also true in same condition for the Documentation! If the Doc page is left open for long enough, clicking on any link will result in the blue loading bar at the top to slowly progress, but the page’s content never changes. I do a hard-refresh in this case too to fix the issue.
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Chris Goddard

10/14/2020, 12:47 PM
yeah +1 for that actually I've found the same thing
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Raphaël Riel

10/14/2020, 12:48 PM
Maybe there’s a shared JS component and/or Websocket thing that’s shared across both the Server’s UI and Documentation?
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Chris Goddard

10/14/2020, 12:49 PM
I think they build everything using Vue.js so it might be some common code that's causing the issue. Prefect team let us know if you want us to file an issue on the UI github repo
so I'm a few years removed from being a front end dev so don't want to step out of my lane but this might be relevant https://vuejs.org/v2/cookbook/avoiding-memory-leaks.html FWIW the memory footprint of the tab does keep growing pretty consistently. I'll check back on the tab in 30 minutes and see where it's at
20 minutes later
going back to the page and clicked to flows and back - page still responsive and memory footprint now down to 217,000k
🕵️‍♂️ 1
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Jenny

10/14/2020, 1:23 PM
Hi @Chris Goddard and @Raphaël Riel - thanks for raising this. We've done quite a bit of work recently on improving performance in the UI and have some more planned. If you can give any more information about the page refresh not working that would be useful as that's not an issue I've previously encountered. The docs performance is separate. I'm going to open an issue for that to make sure it's something we're tracking.
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Raphaël Riel

10/14/2020, 1:48 PM
Just confimed a thing for the Server/Cloud UI. A) Returned (Was not focused on the tab) after 30mins, JS VM was taking 500Mb B) I gave it some time, roughly 15sec, and the Garbage collector managed to drop it to 26Mb C) After that the UI was responsive again. But for all the duration of “B”, the page was mostly blank and unresponsive.
As for the Documentation’s I’ll investigate a little more the next time I hit this problem.
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Jenny

10/14/2020, 1:50 PM
Thanks @Raphaël Riel - can you remember which page that was ( Dashboard, flow page, etc...)?
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Raphaël Riel

10/14/2020, 1:51 PM
Nope, sorry. When retuning the page was blank 😞
But I’m pretty sure this is not page-dependant. My best bet would be on the automatic polling of the GraphQL API
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Jenny

10/14/2020, 1:54 PM
Ok - no worries. I'll see if I can recreate. Thanks for the update.
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Raphaël Riel

10/14/2020, 1:56 PM
Try having a UI open in a non-focused tab for 30+ minutes.
@Jenny As for the Doc, it wasn’t hard to repro. “Pre-loaded” page were working just fine. But pages I had no viewed in the current page-load weren’t loading.
Here’s the Console Error in Text: 
Uncaught SyntaxError: Unexpected token '<'


Uncaught (in promise) ChunkLoadError: Loading chunk 325 failed.
(missing: <https://docs.prefect.io/assets/js/325.6d6048fd.js>)
    at Function.r.e (<https://docs.prefect.io/assets/js/app.0af387ff.js:1:7768>)
    at v-458fb356 (<https://docs.prefect.io/assets/js/app.0af387ff.js:13:49144>)
    at <https://docs.prefect.io/assets/js/app.0af387ff.js:13:58898>
    at u (<https://docs.prefect.io/assets/js/app.0af387ff.js:3:16909>)
    at Generator._invoke (<https://docs.prefect.io/assets/js/app.0af387ff.js:3:16662>)
    at Generator.next (<https://docs.prefect.io/assets/js/app.0af387ff.js:3:17268>)
    at n (<https://docs.prefect.io/assets/js/app.0af387ff.js:3:44371>)
    at s (<https://docs.prefect.io/assets/js/app.0af387ff.js:3:44574>)
    at <https://docs.prefect.io/assets/js/app.0af387ff.js:3:44633>
    at new Promise (<anonymous>)
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Jenny

10/14/2020, 2:03 PM
Thanks @Raphaël Riel
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Raphaël Riel

10/14/2020, 2:04 PM
Please note that for the Server’s UI, I spotted no error when the UI was irresponsive.
Same Behaviour, different causes 😉
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Jenny

10/14/2020, 2:09 PM
One more question/double check - you're seeing the issue in the Server UI - not Cloud?
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Chris Goddard

10/14/2020, 2:09 PM
I'm seeing it on cloud
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Jenny

10/14/2020, 2:11 PM
Thanks @Chris Goddard
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Raphaël Riel

10/14/2020, 2:19 PM
Cloud.
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Jenny

10/14/2020, 2:20 PM
Ah - thanks @Raphaël Riel
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nicholas

10/14/2020, 2:33 PM
Hi @Raphaël Riel and @Chris Goddard - thanks for raising this. As @Jenny mentioned this is on our radar for both the docs and the UI and is something we're actively working on. We've taken some steps recently in the UI that have shown marked improvements but there's still some work to be done; part, but not all, of this is related to a known memory leak in Vue-Apollo, the Apollo-client we use to interface with the Server/Cloud Apollo server. Before I open a new ticket in the UI repo, are you both on the latest version of Server? You mentioned seeing it in Cloud, was that from our hosted UI or your own? @Raphaël Riel are you also on Windows?
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Chris Goddard

10/14/2020, 2:33 PM
I'm using the hosted version
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hey just wanted to follow up because page is now unresponsive (been idle for ~1.5 hours)
ok and it finally loaded - memory footprint is enormous
what's interesting is as soon as I click on another tab (e.g. to flows and back to overview) something gets reset and the memory returns to a normal level
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Raphaël Riel

10/14/2020, 4:15 PM
Lunch time for me. I’ll start a Memory Sampling in Chrome to try to figure out what’s happening (I experience the same behaviour as @Chris Goddard )
Hopefully I’ll have interesting results upon returning.
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Michael Ludwig

10/16/2020, 11:54 PM
Just wanted to quickly mention that this is also a problem we saw. It was on Prefect cloud. But already some weeks back since I checked.
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Alex Joseph

12/23/2020, 7:35 PM
Hi, sorry to bump this old thread - But I'm still facing this issue with MacOSX + Chrome. Has there been any fix/workaround?
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nicholas

12/23/2020, 7:39 PM
Hi @Alex Joseph - this is still something we're working on but don't have an immediate answer to; nevertheless it's on our radar to fix as soon as possible!
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Raphaël Riel

01/04/2021, 1:12 PM
@Alex Joseph Does my Issue report fits your experience on this bug? https://github.com/PrefectHQ/ui/issues/513
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Alex Joseph

01/04/2021, 6:25 PM
@Raphaël Riel - Yes this is exactly the issue I've faced as well, thanks
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