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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Thread safe class method defined in Powershell hangs inside a Lazy inside a ConcurrentDictionary","articleBody":"### Prerequisites\r\n\r\n- [X] Write a descriptive title.\r\n- [X] Make sure you are able to repro it on the [latest released version](https://github.com/PowerShell/PowerShell/releases)\r\n- [X] Search the existing issues.\r\n- [X] Refer to the [FAQ](https://github.com/PowerShell/PowerShell/blob/master/docs/FAQ.md).\r\n- [X] Refer to [Differences between Windows PowerShell 5.1 and PowerShell](https://docs.microsoft.com/powershell/scripting/whats-new/differences-from-windows-powershell).\r\n\r\n### Steps to reproduce\r\n\r\nI have a thread safe class method (it's static and empty) that is hanging when called inside of a ```System.Lazy``` initializer inside of a ```System.Collections.Concurrent.ConcurrentDictionary``` when used with ```ForEach-Object -Parallel```. Calling a normal dotnet method works fine (e.g. ```[System.Convert]::ToString(132456, 2)```), but my ```[Dead]::Lock()``` method call hangs.\r\n\r\nThis is as far as I was able to strip my repro code down while still causing the hang:\r\n````Powershell\r\n#Requires -Version 7\r\n\r\nWrite-Host \"Starting job`n\"\r\n\r\n$dict = [System.Collections.Concurrent.ConcurrentDictionary[string, System.Lazy[string]]]::new()\r\n\r\n$job = 1..16 | ForEach-Object -AsJob -ThrottleLimit 16 -Parallel {\r\n    $threadNum = $_\r\n    $dict = $using:dict\r\n\r\n    class Dead {\r\n        # This method should be thread safe(?)\r\n        static [void] Lock() {\r\n        }\r\n    }\r\n\r\n    [System.Console]::WriteLine(\"Starting thread #$threadNum\")\r\n\r\n    $lazy = $dict.GetOrAdd(\"same key\", [System.Lazy[string]]::new(\r\n        {\r\n            # Calling this method causes the script to hang, even though it should(?) be thread safe\r\n            [Dead]::Lock()\r\n\r\n            $okToCall = [System.Convert]::ToString(132456, 2)\r\n            return \"\"\r\n        },\r\n        [System.Threading.LazyThreadSafetyMode]::ExecutionAndPublication))\r\n\r\n    [void]$lazy.Value\r\n\r\n    [System.Console]::WriteLine(\"Completed thread #$threadNum\")\r\n}\r\ntry {\r\n    while (!$job.Finished.WaitOne(1000)) {\r\n        Write-Host \"$(Get-Date): Waiting\"\r\n    }\r\n    $job | Receive-Job\r\n\r\n    Write-Host \"`nFinished job`n\"\r\n} finally {\r\n    $job | Stop-Job\r\n}\r\n````\r\n\r\nNote: you may need to run this a bunch of times to actually see the hang. I'm also running this without my profile to ensure that's not interfering: ```pwsh.exe -NoProfile -File $Home\\OneDrive\\Scripts\\bug.ps1```\r\n\r\nI've had independent verification of the hang from at least one other user.\r\n\r\n### Expected behavior\r\n\r\n```console\r\nPS C:\\\u003e pwsh.exe -NoProfile -File $Home\\OneDrive\\Scripts\\bug.ps1\r\nStarting job\r\n\r\nStarting thread #1\r\nStarting thread #2\r\nStarting thread #3\r\nStarting thread #4\r\nStarting thread #5\r\nStarting thread #6\r\nStarting thread #7\r\nStarting thread #8\r\nStarting thread #9\r\nStarting thread #10\r\nStarting thread #11\r\nStarting thread #12\r\nStarting thread #13\r\nStarting thread #14\r\nStarting thread #15\r\nStarting thread #16\r\nCompleted thread #2\r\nCompleted thread #6\r\nCompleted thread #9\r\nCompleted thread #13\r\nCompleted thread #3\r\nCompleted thread #1\r\nCompleted thread #4\r\nCompleted thread #5\r\nCompleted thread #7\r\nCompleted thread #8\r\nCompleted thread #10\r\nCompleted thread #11\r\nCompleted thread #12\r\nCompleted thread #14\r\nCompleted thread #15\r\nCompleted thread #16\r\n\r\nFinished job\r\n\r\nPS C:\\\u003e\r\n```\r\n\r\n\r\n### Actual behavior\r\n\r\n```console\r\nPS C:\\\u003e pwsh.exe -NoProfile -File $Home\\OneDrive\\Scripts\\bug.ps1\r\nStarting job\r\n\r\nStarting thread #2\r\nStarting thread #1\r\nStarting thread #3\r\nStarting thread #4\r\nStarting thread #5\r\nStarting thread #6\r\nStarting thread #7\r\nStarting thread #8\r\nStarting thread #9\r\nStarting thread #10\r\nStarting thread #11\r\nStarting thread #12\r\nStarting thread #13\r\nStarting thread #14\r\nStarting thread #15\r\nStarting thread #16\r\n10/10/2022 11:52:52: Waiting\r\n10/10/2022 11:52:53: Waiting\r\n10/10/2022 11:52:54: Waiting\r\n10/10/2022 11:52:55: Waiting\r\n10/10/2022 11:52:56: Waiting\r\n10/10/2022 11:52:57: Waiting\r\n10/10/2022 11:52:58: Waiting\r\n10/10/2022 11:52:59: Waiting\r\n10/10/2022 11:53:00: Waiting\r\n10/10/2022 11:53:01: Waiting\r\n10/10/2022 11:53:02: Waiting\r\n```\r\n\r\n\r\n### Error details\r\n\r\n_No response_\r\n\r\n### Environment data\r\n\r\n```powershell\r\nName                           Value\r\n----                           -----\r\nPSVersion                      7.2.6\r\nPSEdition                      Core\r\nGitCommitId                    7.2.6\r\nOS                             Microsoft Windows 10.0.22621\r\nPlatform                       Win32NT\r\nPSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}\r\nPSRemotingProtocolVersion      2.3\r\nSerializationVersion           1.1.0.1\r\nWSManStackVersion              3.0\r\n```\r\n\r\n\r\n### Visuals\r\n\r\n_No response_","author":{"url":"https://github.com/User1785604260","@type":"Person","name":"User1785604260"},"datePublished":"2022-10-10T14:53:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/18248/PowerShell/issues/18248"}