Server stops with errors "Collection was modified after..."

[nightroman]

Describe the Bug

Server stops with the error "Collection was modified after the enumerator was instantiated."

Steps To Reproduce

Steps to reproduce the behavior:

2024-03-25-server-stops.zip

(1) Start the attached server.ps1, rather trivial one route server.

(2) In the opened browser keep refreshing the page with brief processes details.
Alternatively, run the attached loop.ps1 which sends similar requests in a loop.

(3) At some point, sometimes soon or after a while, the server stops with errors like:

Test-PodeRestartPressed: C:\Program Files\WindowsPowerShell\Modules\Pode\2.9.0\Public\Core.ps1:194
Line |
 194 |  … t.IsCancellationRequested) -or (Test-PodeRestartPressed -Key $key)) {
     |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     | Collection was modified after the enumerator was instantiated.

Errors may be at different locations and about different keys tested.

Expected Behavior

Ideally, the error should not happen, with its reasons avoided.

If this is not possible errors should be caught and ignored.

Platform

• OS: Windows 11
• Browser: Chrome
• Versions:
  • Pode: 2.9.0
  • PowerShell: 7.4.1

[mdaneri]

It's a bug due to the way Powershell deals with array and piping.

We have to make the Write-PodeTextResponse and Write-PodeHtmlResponse "piping compliance"

Try this one

Start-PodeServer {
    Add-PodeEndpoint -Address localhost -Port 8081 -Protocol Http
    #working
    Add-PodeRoute -Path '/processes'  -Method Get -ScriptBlock {
        $r = Get-Process | .{ process { if ($_.WS -gt 100mb) { $_ } } } |
            Select-Object Name, @{e = { [int]($_.WS / 1mb) }; n = 'WS' } |
            Sort-Object WS -Descending

        Write-PodeHtmlResponse -Value $r  -StatusCode 200
    }
    #not working
    Add-PodeRoute -Path '/processesPipedNotWorking'  -Method Get -ScriptBlock {
        Get-Process | .{ process { if ($_.WS -gt 100mb) { $_ } } } |
            Select-Object Name, @{e = { [int]($_.WS / 1mb) }; n = 'WS' } |
            Sort-Object WS -Descending | Write-PodeHtmlResponse  -StatusCode 200
    }

    #this is like the previous one
    Add-PodePage -Name NotWorkingProcesses -ScriptBlock {
        Get-Process | .{ process { if ($_.WS -gt 100mb) { $_ } } } |
            Select-Object Name, @{e = { [int]($_.WS / 1mb) }; n = 'WS' } |
            Sort-Object WS -Descending
    }

    Start-Process http://localhost:8081/processes
}

[mdaneri]

I found the real problem, and it's not related to the piping issue.

I'm going to open a bug for the piping issues with arrays