FileManager sending a massive quantity of messages on Blazor SignalR connection, causing server memory to increase and eventually hang.

Question

Hi Syncfusion,I'm using Blazor FileManager component 23.1.38 in a Blazor Server .NET 8.0 project.I've written an API controller that the FileManager calls for folder and file data.  This controller talks to a SQL database for the data, and is based upon the Syncfusion example.All seems to work okay except for when a user attempts to open a folder by double-clicking in the right-hand display pane and, I think, only when it is a second level or deeper folder that is accessed.  The application in the browser freezes and begins to send a massive number of messages to the server on the Blazor SignalR connection.  These messages cause the server memory to increase and eventually the server hangs.  A very bad situation indeed.This is one of the messages:

Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher: Debug: Received hub invocation: InvocationMessage { InvocationId: "", Target: "EndInvokeJSFromDotNet", Arguments: [ 875, False, [875,false,"Cannot read properties of null (reading 'querySelector')
TypeError: Cannot read properties of null (reading 'querySelector')
 at Object.ye [as select] (https://localhost:7165/_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js:1:64825)
 at b.expandedNode (https://localhost:7165/_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js:23:1579533)
 at Object.expandedNode (https://localhost:7165/_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js:23:1595459)
 at https://localhost:7165/_framework/blazor.server.js:1:3244
 at new Promise (<anonymous>)
 at y.beginInvokeJSFromDotNet (https://localhost:7165/_framework/blazor.server.js:1:3201)
 at Yt._invokeClientMethod (https://localhost:7165/_framework/blazor.server.js:1:60713)
 at Yt._processIncomingData (https://localhost:7165/_framework/blazor.server.js:1:58188)
 at Yt.connection.onreceive (https://localhost:7165/_framework/blazor.server.js:1:51829)
 at s.onmessage (https://localhost:7165/_framework/blazor.server.js:1:79974)"] ], StreamIds: [ ] }.On my development PC there are sent approximately 120 messages per second, in batches of around 30. each batch separated by 250ms.What can it be causing this?Your example which uses the PhysicalFileProvider does not exhibit this behaviour so I'm wondering if it might be something to do with the data returned to the FileManager from my API.  Data coming from SQL needs to be subtly different to the physical file situation because IDs are involved.  But surely no amount of bad data returned from the API should make the FileManager hang the server with messages?Do you have any ideas what might be happening here?  Has this been reported before now?Best regards,Steve

Prasanth Madhaiyan · Answer

Hi Stephen,Greetings from Syncfusion support.Based on the shared details, we understand that you are
facing an issue with the Blazor FileManager component and the SQL provider.
When attempting to open a folder (second level or deeper folder) by
double-clicking on the FileManager details view pane, the application in the
browser freezes and begins to send a massive number of messages to the server
at your end. However, we have prepared the Blazor FileManager sample and
connected it with the SQL Provider. While checking at our end, we were unable
to replicate the reported issue in the mentioned and latest NuGet version.For your reference, we have attached the sample and video
footage in a zip file.Please check out the attached sample, and if the issue still
persists, could you please replicate the issue in the attached sample or share
the replicated sample along with video footage for better understanding? This
will help us to reproduce the exact issue at our end, and based on that, we
will check and provide you with a prompt solution. Kindly get back to us with
the requested details.Regards,Prasanth Madhaiyan.Attachment: SampleAndVideo_fe8462db.zip

Stephen Haines · Answer

Thank you for your quick response Prasanth,

I will do as you ask.

In the meantime, please can you confirm that the Blazor SignalR messages I'm seeing on the server (viewed in Visual Studio's output window as a result of adding "Microsoft.AspNetCore.SignalR": "Debug" to logging in appsettings.json) are coming from the FileManager in the browser. If they are, then why?

I've attached a sample of the messages, filemanager_debug.txt.

Best regards,

Steve

Attachment: filemanager_debug_b981cf7.zip

Stephen Haines · Answer

Hi,I used the Syncfusion SQLFileProvider example code and successfully reproduced the issue described above.  Not with your SQL data but with mine.  I simply added rows manually to the table "Products2" until the issue appeared.  There are just nine rows in my table.I have attached two .sql scripts: create_table.sql creates the "Products2" table and "insert_data.sql" inserts the 9 rows.  Please create the table and see what happens there.I just can't see what's causing the problem.Regards,SteveAttachment: sql_ae8f2098.zip

Prasanth Madhaiyan · Answer

Hi Stephen,Based on the SQL table data you shared, we have prepared a
Blazor FileManager component sample by connecting it with the SQL service
provider. However, while checking the reported issue, 'when attempting to
open a folder (second level or deeper folder) by double-clicking on the
FileManager details view pane, the application in the browser freezes and
begins to send a massive number of messages to the server’, we were unable
to replicate this issue on our end. For your reference, we have attached the sample, SQL service
provider, and video footage in a zip file.Please review the attached sample. If the issue persists,
could you replicate the problem in the provided sample or share the replicated
sample along with video footage for better understanding? This will help us
reproduce the exact issue on our end, and based on that, we will check and
provide you with a prompt solution. Kindly get back to us with the requested
details.Regards,Prasanth Madhaiyan.Attachment: SampleAndVideo_ed6cc4a7.zip

Stephen Haines · Answer

Hi Prasanth,I have reproduced the issue with your example, albeit with a slightly different result.To begin with I removed all rows from your database table except the first (the row with ItemID=1).  I then added two folders to the root and one folder to the first of those.I run the example.  Double-click on the folder named "1".  All okay.  Double-click on the folder named "1.1".  The application freezes.  (It was at this point I previously saw continuous SignalR messages, but this did not happen here).  After a few seconds the application crashes with the error: The program 'iisexpress.exe' has exited with code 3221225477 (0xc0000005) 'Access violation'.This normally indicates some kind of infinite recursive call.Video attached.Please could you investigate.Regards,SteveAttachment: Recording_20231217_205523_6ae87671.zip

Prasanth Madhaiyan · Answer

Hi Stephen,We have checked the reported issue in the Blazor FileManager
component with the SQL provider. We consider this a bug on our end and will
update the feedback and timeline-related details shortly.Regards,Prasanth Madhaiyan.

Prasanth Madhaiyan · Answer

Hi Stephen,The fix for this issue will be included in the weekly patch
release scheduled for December 26, 2023. You can track the status of the fix
through the following link.Feedback: https://www.syncfusion.com/feedback/49347/facing-an-issue-when-opening-a-folder-in-the-large-icon-view-in-the-blazorDisclaimer: Inclusion of this solution in the weekly
release may change due to other factors including but not limited to QA checks
and works reprioritization.Regards,Prasanth Madhaiyan.

Stephen Haines · Answer

Hi Prasanth,Thank you.  Your kind attention in this matter is much appreciated.Best regards,Steve

SureshRajan Alagarsamy · Answer

Hi Stephen,Thanks for your patience.We are glad to announce that our patch release (v24.1.44)
has been rolled out successfully. The issue with "Facing an issue when
opening a folder in the large icon view in the Blazor FileManager with SQL
provider” has been resolved in this release.To access this fix, we suggest you update the package to 24.1.44
and we include the sample in the latest version for your reference.Sample: Attached as zip folder.Feedback: https://www.syncfusion.com/feedback/49347/facing-an-issue-when-opening-a-folder-in-the-large-icon-view-in-the-blazorRelease Notes: https://blazor.syncfusion.com/documentation/release-notes/24.1.44?type=all#file-managerRegards,Suresh.Attachment: File_ManagerSQL_Provider_c7b3f988.zip

Stephen Haines · Answer

Hi Suresh and Syncfusion,I have tested the code in your attachment and I'm am sorry to report that it is still possible to recreate the issue once a file has been uploaded.Here are the steps to reproduce:Start the SQLProvider.Start the Blazor App.  You will see the empty folders in your example mdb.In the large icon view, open folder 1, then folder 1.1, then NewFolder.  No problems.  I repeated this 20 times with no problems.﻿﻿Restart the Blazor App.  In the large icon view, open folder 1.  Upload a jpeg into folder 1.Double-click on the icon for folder 1.1.  The application hangs and the server memory starts to ramp up.Restart the Blazor App and attempt to navigate to folder 1.1.  Each time the application hangs and server memory starts to ramp up.Please see the attached screenshot showing the point in time just after the application has hung.Best regards,SteveAttachment: screenshot_b7910228.zip

SureshRajan Alagarsamy · Answer

Hi Stephen,We have checked the reported issue in the Blazor FileManager
component with the SQL provider. We were able to replicate the reported issue.
We have consider this a bug on our end. The fix for this issue will be included
in the weekly patch release scheduled for February 13, 2024.You can track the status of the fix through the following
link.Feedback: https://www.syncfusion.com/feedback/50544/persistent-spinner-loading-issue-when-opening-a-folder-in-the-large-icon-view-inDisclaimer: Inclusion of this solution in the weekly
release may change due to other factors including but not limited to QA checks
and works reprioritization.Regards,
Suresh.

Prasanth Madhaiyan · Answer

Hi Stephen,On further validation, we would like to inform you that the
reported 'Persistent spinner loading issue when opening a folder in the
large icon view in the Blazor FileManager with SQL provider' occurs because
the 'HasChild' value of 'Folder 1' is false in the SQL
table. However, the folder has a 'Folder 1.1' child in it. Therefore, we
suggest changing the 'hasChild' value of 'Folder 1' to true
in the SQL table, which will resolve the mentioned issue on our end.Screenshot:

Additionally, please confirm whether you have reported this
issue. If not, could you please share the exact issue you were facing at your
end with video footage of the issue for our easy understanding in the Blazor
FileManager with the SQL provider? Based on that, we will investigate and
provide you with a prompt solution. Kindly get back to us with the requested
details.Regards,Prasanth Madhaiyan.

Stephen Haines · Answer

Dear Prasanth & Syncfusion,I recreated the reported issue with your own sample (File_ManagerSQL_Provider_c7b3f988.zip) sent by you on 9th January 2024, as described in my message to you in this thread on 30th January 2024.I have run the tests again and confirm that the IsRoot values are correct and as expected.  The issue must be caused by something else.Regards,Steve

Prasanth Madhaiyan · Answer

Hi Stephan,Based on the shared details, we understand that you were
facing a hanging issue in the Blazor FileManager with SQL Provider at your end.
However, we performed the exact reproduction steps at our end to replicate the
mentioned scenario. However, we were unable to encounter any hanging issues in
the FileManager component, and it is functioning properly without any problems.For your reference, we have attached the video footage and
sample. Sample and video: Attached as a zip file. Please check the video footage, and we recommend you review
the shared sample at your end. If the issue still persists, could you please
provide video footage that will help us replicate it on our end? Additionally,
share the uploaded file with us. Based on that, we will investigate and provide
you with a prompt solution. Kindly get back to us with the requested details.Regards,Prasanth Madhaiyan.Attachment: File_ManagerSQL_Provider_Sample_96b1cd56.zip

Stephen Haines · Answer

Hi Prasanth & Syncfusion,I am confused by your most recent message saying that you are unable to reproduce the issue.  In a previous message, dated February 2nd 2024,  you did reproduce, using your own example and undertook to provide a fix by 13th February 2024.You wrote:

We have checked the reported issue in the Blazor FileManager component with the SQL provider. We were able to replicate the reported issue. We have consider this a bug on our end. The fix for this issue will be included in the weekly patch release scheduled for February 13, 2024.

I recreated the reported issue with your own sample (File_ManagerSQL_Provider_c7b3f988.zip) sent by you on 9th January 2024, as described in my message to you in this thread on 30th January 2024.  I confirm that the database IsRoot values are correct and as expected.  The issue must be caused by something else.Steve

Prasanth Madhaiyan · Answer

Hi Stephan,Sorry for the inconvenience.Based on the shared details, we would like to inform you
that the reported 'Persistent spinner loading issue when opening a folder in
the large icon view in the Blazor FileManager with SQL provider' occurs because
the 'HasChild' value of 'Folder 1' is false in the SQL
table. This was mistakenly added at our end, and we apologize for this
action. After that, when we performed the exact reproduction steps provided by
you at our end to replicate the mentioned scenario, we were unable to replicate
any hanging issues in the FileManager component, even though we uploaded the
000000-00000.jpeg file at our end in the FileManager component based on the
shared screenshot of yours.For your reference, we have attached the sample and video
footage as a zip file.Please review the video footage, and we recommend examining
the shared sample on your end. If the issue persists, could you kindly provide
video footage that will assist us in replicating it on our end? Additionally,
please share the uploaded file with us. Based on this information, we will
investigate and provide you with a prompt solution. Kindly get back to us with
the requested details.Regards,Prasanth Madhaiyan.Attachment: File_ManagerSQL_Provider_Sample_208b36ad.zip

Stephen Haines · Answer

Hi Guys,I can not run your most recent sample.  It targets version 24.2.5.  I have added the key you provide but licensing is unsuccessful.Please advise.Steve

Prasanth Madhaiyan · Answer

Hi Stephan,Based on the shared details, we understand that you were
facing a license-related issue when running our previous update sample.
However, now for your reference, we have attached the FileManager sample with
an SQL provider.Sample and SQL Provider: Attached as a zip file.Check out the attached sample and If the issue persists,
could you kindly provide video footage that will assist us in replicating it on
our end? Additionally, please share the uploaded file with us. Based on this
information, we will investigate and provide you with a prompt solution. Kindly
get back to us with the requested details.Regards,Prasanth Madhaiyan.Attachment: File_ManagerSQL_Provider_Sample_dc2c5f6a.zip

Stephen Haines · Answer

Hi Prasanth & Syncfusion,Your sample does recreate the issue.Start BlazorAppDouble click on Folder 1Double click on Folder 1.1.  The application freezes, continuous hub messages are generated and the memory usage ramps up.You might have to repeat the steps once or twice to see the issue, but once it happens, it happens consistently.Please see the attached video.SteveAttachment: Recording_20240219_125509_651e7fd7.zip

Prasanth Madhaiyan · Answer

Hi Stephen,Based on the shared details, while checking on our end now,
we were able to replicate the mentioned issue. However, we need some additional
time for further validation to determine the exact cause on our end, and we
will update you with further details shortly. We appreciate your patience.Regards,Prasanth Madhaiyan.

Prasanth Madhaiyan · Answer

Hi Stephen,We have checked the reported issues in the Blazor
FileManager with the SQL provider and considered it a bug at our end. The fix
for this issue will be included in the Volume 1 main release scheduled for
mid-March 2024. You can track the status of the fix through the following link.Feedback: https://www.syncfusion.com/feedback/51166/facing-a-console-error-when-double-clicking-to-open-the-folder-in-the-blazorRegards,Prasanth Madhaiyan.

Prasanth Madhaiyan · Answer

Hi Stephen,We are glad to announce that Essential Studio 2024 Volume 1 Main Release v25.1.35 is
rolled out and is available for download under the following link.Essential
Studio 2024 Volume 1 Main Release v25.1.35 is available for download |
Announcements Forums | SyncfusionThe issue with the “Facing a console error when
double-clicking to open the folder in the Blazor FileManager with SQL provider”
has been resolved in this release. To access this fix, we suggest you
update the package to 25.1.35 and we include the sample in the latest
version for your reference.Sample: https://www.syncfusion.com/downloads/support/directtrac/general/ze/File_ManagerSQL_Provider_Sample931431561.zipFeedback: https://www.syncfusion.com/feedback/51166/facing-a-console-error-when-double-clicking-to-open-the-folder-in-the-blazorRelease Notes: https://blazor.syncfusion.com/documentation/release-notes/25.1.35?type=all#file-managerWe thank you for your support and appreciate
your patience in waiting for this release. Please get in touch with us if you
would require any further assistance.Regards,Prasanth Madhaiyan.