{"id":8211,"date":"2007-03-23T15:50:00","date_gmt":"2007-03-23T15:50:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/powershell\/2007\/03\/23\/thread-apartmentstate-and-powershell-execution-thread\/"},"modified":"2019-02-18T13:16:46","modified_gmt":"2019-02-18T20:16:46","slug":"thread-apartmentstate-and-powershell-execution-thread","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/powershell\/thread-apartmentstate-and-powershell-execution-thread\/","title":{"rendered":"Thread.ApartmentState and PowerShell Execution Thread"},"content":{"rendered":"

Recently someone, in internal discussion groups, asked if it is possible to set \u201cApartmentState\u201d on the powershell\u2019s execution thread. I thought this info is useful to some of you and hence this blog.  <\/span>To touch basics on ApartmentState see <\/font>http:\/\/msdn.microsoft.com\/library\/default.asp?url=\/library\/en-us\/cpref\/html\/frlrfsystemthreadingapartmentstateclasstopic.asp<\/font><\/a><\/p>\n

Majority of PowerShell\u2019s execution happens through Pipeline class. PowerShell\u2019s  <\/span>ConsoleHost  <\/span>constructs a pipeline with user requested command +  <\/span>input and invoke<\/b>s the pipeline. This is true for any host built on top of PowerShell. Pipeline\u2019s Invoke method creates a child thread and delegates execution to this child thread. Unfortunately in v1.0 release, there is no way to set the ApartmentState of this child thread. By default CLR initializes new threads as \u201cMTA\u201d and there is no way to change the ApartmentState once the thread is started. As a result of this a cmdlet always runs in MTA thread when invoked using Pipeline.<\/font><\/p>\n

There is no easy solution to this problem. If you want to execute your cmdlet in \u201cSTA\u201d apartment, your cmdlet should create a new thread + change apartment state to \u201cSTA\u201d -> then execute the task in this child thread. One way of achieving this is creating a new cmdlet with the same functionality as invoke-expression cmdlet to take \u201cApartment\u201d as the parameter (Invoke-Expression is a sealed class, so we cannot extend from this class).  <\/span>I am calling this cmdlet \u201cInvoke-Apartment<\/b>\u201d. Here is how it works:<\/font><\/p>\n

PS C:\\temp> get-command invoke-apartment | select definition | fl *<\/font><\/font><\/b><\/p>\n

Definition: Invoke-Apartment [-Apartment] <ApartmentState> [-Expression] <String> <\/font><\/font><\/b><\/p>\n

The cmdlet takes an \u201cApartmentState\u201d and executes \u201cExpression\u201d in that apartment.  It creates a new Thread with the user requested ApartmentState -> constructs a ScriptBlock with the expression supplied by the user -> executes the ScriptBlock in this child thread.<\/font><\/p>\n

The behavior is as follows:<\/font><\/p>\n

PS C:\\temp> invoke-apartment “MTA” \u201c[System.Threading.Thread]::CurrentThread.GetApartmentState()”<\/font><\/font><\/b><\/p>\n

MTA<\/font><\/font><\/b><\/p>\n

PS C:\\temp> invoke-apartment “STA” “[System.Threading.Thread]::CurrentThread.GetApartmentState()”<\/font><\/font><\/b><\/p>\n

STA<\/font><\/font><\/b><\/p>\n

To achieve this, I did the following:<\/font><\/p>\n

1.<\/font>       <\/span><\/span><\/span>A ScriptBlock is constructed using \u201cExpression\u201d parameter.<\/font><\/p>\n

2.<\/font>       <\/span><\/span><\/span>A new thread is created and ApartmentState is set to the one requested by the user (if current apartment state is not what user requested).<\/font><\/p>\n

3.<\/font>       <\/span><\/span><\/span>ScriptBlock is invoked in the new thread while the parent thread waits for task completion.<\/font><\/p>\n

4.<\/font>       <\/span><\/span><\/span>ScriptBlock.InvokeReturnAsIs() needs a runspace to execute the script and it looks for runspace in the Thread-Local storage (TLS)<\/font><\/p>\n

5.<\/font>       <\/span><\/span><\/span>Since we are executing in a different thread, we need to set Runspace.DefaultRunspace on this thread as well. [Runspace.DefaultRunspace = somerunspace actually updates the TLS]<\/font><\/p>\n

Note: It is not recommended to execute cmdlets out of the pipeline context as described here as Runspace cannot handle multiple execuitons at the same time like this. Also there is a potential risk of compromising global variables state. <\/font><\/p>\n

<\/span><\/font><\/p>\n

Thanks <\/span><\/font><\/p>\n

Krishna Vutukuri<\/span><\/span><\/font><\/p>\n

Microsoft PowerShell Development<\/font><\/span> <\/span><\/p>\n

This posting is provided “AS IS” with no rights and warranties.<\/span><\/p>\n

<\/font> <\/p>\n

\/*  <\/span><\/span><\/p>\n

 <\/span>The code here is provided AS IS with no rights or warranties of any kind. Use it at your own discretion. <\/span><\/p>\n

 <\/span>*\/<\/span> <\/span><\/p>\n

 <\/span><\/p>\n

using<\/span> System;<\/span><\/p>\n

using<\/span> System.Collections.Generic;<\/span><\/p>\n

using<\/span> System.Text;<\/span><\/p>\n

using<\/span> System.Threading;<\/span><\/p>\n

using<\/span> System.ComponentModel;<\/span><\/p>\n

using<\/span> System.Configuration;<\/span><\/p>\n

using<\/span> System.Collections.ObjectModel;<\/span><\/p>\n

 <\/span><\/p>\n

using<\/span> System.Management.Automation;<\/span><\/p>\n

using<\/span> System.Management.Automation.Runspaces;<\/span><\/p>\n

 <\/span><\/p>\n

namespace<\/span> Powershell.Blogs<\/span><\/p>\n

{<\/span><\/p>\n

    <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

    <\/span>\/\/\/<\/span> Class implemeting Invoke-Apartment<\/span><\/span><\/p>\n

    <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

    <\/span>[Cmdlet<\/span>(“Invoke”<\/span>, “Apartment”<\/span>)]<\/span><\/p>\n

    <\/span>public<\/span> sealed<\/span><\/span><\/p>\n

    <\/span>class<\/span><\/span><\/p>\n

    <\/span>InvokeApartmentCommand<\/span> : PSCmdlet<\/span><\/span><\/p>\n

    <\/span>{<\/span><\/p>\n

        <\/span>internal<\/span> class<\/span> ExecutionResult<\/span><\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>private<\/span> object<\/span> output;<\/span><\/p>\n

            <\/span>private<\/span> Exception<\/span> error;<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>public<\/span> Object<\/span> Output<\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>get<\/span> { return<\/span> output; }<\/span><\/p>\n

                <\/span>set<\/span> { output = value<\/span>; }<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>public<\/span> Exception<\/span> Error<\/span><\/p>\n

     <\/span>       <\/span>{<\/span><\/p>\n

                <\/span>get<\/span> { return<\/span> error; }<\/span><\/p>\n

                <\/span>set<\/span> { error = value<\/span>; }<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>#region<\/span> Private Data<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>private<\/span> ManualResetEvent<\/span> waitHandle;<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>private<\/span> Runspace<\/span> runspace;<\/span><\/p>\n

        <\/span>private<\/span> Runspace<\/span> Runspace<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>get<\/span><\/span><\/p>\n

            <\/span>{                <\/span><\/span><\/p>\n

                <\/span>return<\/span> runspace;<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>set<\/span><\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>runspace = value<\/span>;<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>#endregion<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>#region<\/span> parameters<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>private<\/span> string<\/span> command;<\/span><\/p>\n

        <\/span>private<\/span> ApartmentState<\/span> apartment = ApartmentState<\/span>.MTA;<\/span><\/p>\n

        <\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> Apartment to run the cmdlet int<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

        <\/span>[Parameter<\/span>(Position = 0, Mandatory = true<\/span>)]<\/span><\/p>\n

        <\/span>public<\/span> ApartmentState<\/span> Apartment<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>get<\/span> { return<\/span> apartment; }<\/span><\/p>\n

            <\/span>set<\/span> { apartment = value<\/span>; }<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> Command to execute.<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

        <\/span>[Parameter<\/span>(Position = 1, Mandatory = true<\/span>, ValueFromPipeline = true<\/span>)]<\/span><\/p>\n

        <\/span>public<\/span> string<\/span> Expression<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>get<\/span> {  <\/span>return<\/span> command; }<\/span><\/p>\n

            <\/span>set<\/span> { command = value<\/span>; }<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>#endregion<\/span> parameters<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>protected<\/span> override<\/span> void<\/span> BeginProcessing()<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

        <\/span>    <\/span>\/\/ Set the runspace<\/span><\/span><\/p>\n

            <\/span>Runspace = Runspace<\/span>.DefaultRunspace;<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> For each record, execute it, and push the results into the <\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> success stream.<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

        <\/span>protected<\/span> override<\/span> void<\/span> ProcessRecord()<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>ExecutionResult<\/span> result = new<\/span> ExecutionResult<\/span>();<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>if<\/span> (Thread<\/span>.CurrentThread.GetApartmentState() == apartment)<\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>\/\/ Since the current apartment state is same as the one requested<\/span><\/span><\/p>\n

                <\/span>\/\/ do the work in same thread.<\/span><\/span><\/p>\n

                <\/span>DoWork(result);<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

            <\/span>else<\/span><\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>\/\/ the apartment state is different..perform the task in <\/span><\/span><\/p>\n

                <\/span>\/\/ a differnt thread.<\/span><\/span><\/p>\n

                <\/span>Thread<\/span> executionThread = new<\/span> Thread<\/span>(new<\/span> ParameterizedThreadStart<\/span>(PerformExecution));<\/span><\/p>\n

                <\/span>executionThread.SetApartmentState(apartment);<\/span><\/p>\n

 <\/span><\/p>\n

                <\/span>\/\/ Create a handle to wait for completion<\/span><\/span><\/p>\n

                <\/span>waitHandle = new<\/span> ManualResetEvent<\/span>(false<\/span>);<\/span><\/p>\n

                <\/span>executionThread.Start(result);<\/span><\/p>\n

 <\/span><\/p>\n

                <\/span>waitHandle.WaitOne();<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

                        <\/span><\/span><\/p>\n

            <\/span>if<\/span> (null<\/span> != result.Error)<\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

         <\/span>       <\/span>throw<\/span> result.Error;<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>if<\/span> (null<\/span> != result.Output)<\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>WriteObject(result.Output);<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>private<\/span> void<\/span> PerformExecution(object<\/span> outputToWriteTo)<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>ExecutionResult<\/span> result = (ExecutionResult<\/span>)outputToWriteTo;<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>\/\/ Use the runspace to execute the script<\/span><\/span><\/p>\n

            <\/span>Runspace<\/span>.DefaultRunspace = Runspace;<\/span><\/p>\n

 <\/span><\/p>\n

            <\/span>DoWork(result);<\/span><\/p>\n

            <\/span><\/span><\/p>\n

            <\/span>if<\/span> (null<\/span> != waitHandle)<\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>waitHandle.Set();<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>private<\/span> void<\/span> DoWork(ExecutionResult<\/span> result)<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>try<\/span><\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>ScriptBlock<\/span> myScriptBlock = InvokeCommand.NewScriptBlock(Expression);<\/span><\/p>\n

                <\/span>result.Output = myScriptBlock.InvokeReturnAsIs(null<\/span>);<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

            <\/span>catch<\/span> (Exception<\/span> e)<\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>result.Error = e;<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

        <\/span><\/span><\/p>\n

    <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

    <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

    <\/span>\/\/\/<\/span> Create this sample as a PowerShell snap-in<\/span><\/span><\/p>\n

    <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

    <\/span>[RunInstaller<\/span>(true<\/span>)]<\/span><\/p>\n

    <\/span>public<\/span> class<\/span> InvokeApartmentPSSnapIn<\/span> : PSSnapIn<\/span><\/span><\/p>\n

    <\/span>{<\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> Create an instance of the InvokeApartmentPSSnapIn<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

        <\/span>public<\/span> InvokeApartmentPSSnapIn()<\/span><\/p>\n

            <\/span>: base<\/span>()<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> Get a name for this PowerShell snap-in. This name will be used in registering<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> this PowerShell snap-in.<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

        <\/span>public<\/span> override<\/span> string<\/span> Name<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>get<\/span><\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>return<\/span> “InvokeApartmentSample”<\/span>;<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> Vendor information for this PowerShell snap-in.<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

        <\/span>public<\/span> override<\/span> string<\/span> Vendor<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>get<\/span><\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>return<\/span> “PowershellBlog”<\/span>;<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

 <\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><summary><\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> Description of this PowerShell snap-in.<\/span><\/span><\/p>\n

        <\/span>\/\/\/<\/span> <\/span><\/summary><\/span><\/span><\/p>\n

        <\/span>public<\/span> override<\/span> string<\/span> Description<\/span><\/p>\n

        <\/span>{<\/span><\/p>\n

            <\/span>get<\/span><\/span><\/p>\n

            <\/span>{<\/span><\/p>\n

                <\/span>return<\/span> “This is a PowerShell snap-in that includes the invoke-apartment cmdlet.”<\/span>;<\/span><\/p>\n

            <\/span>}<\/span><\/p>\n

        <\/span>}<\/span><\/p>\n

    <\/span>}<\/span><\/p>\n

}<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Recently someone, in internal discussion groups, asked if it is possible to set \u201cApartmentState\u201d on the powershell\u2019s execution thread. I thought this info is useful to some of you and hence this blog.  To touch basics on ApartmentState see http:\/\/msdn.microsoft.com\/library\/default.asp?url=\/library\/en-us\/cpref\/html\/frlrfsystemthreadingapartmentstateclasstopic.asp Majority of PowerShell\u2019s execution happens through Pipeline class. PowerShell\u2019s  ConsoleHost  constructs a pipeline with user […]<\/p>\n","protected":false},"author":600,"featured_media":13641,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-8211","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-powershell"],"acf":[],"blog_post_summary":"

Recently someone, in internal discussion groups, asked if it is possible to set \u201cApartmentState\u201d on the powershell\u2019s execution thread. I thought this info is useful to some of you and hence this blog.  To touch basics on ApartmentState see http:\/\/msdn.microsoft.com\/library\/default.asp?url=\/library\/en-us\/cpref\/html\/frlrfsystemthreadingapartmentstateclasstopic.asp Majority of PowerShell\u2019s execution happens through Pipeline class. PowerShell\u2019s  ConsoleHost  constructs a pipeline with user […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts\/8211","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/users\/600"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/comments?post=8211"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts\/8211\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/media\/13641"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/media?parent=8211"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/categories?post=8211"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/tags?post=8211"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}