A scheduled job without a trigger has to be run manually, but each job can have many triggers. By contrast, below is the code used for the runspace version. Multithreading Script Welcome › Forums › General PowerShell Q&A › Multithreading Script This topic has 1 reply, 1 voice, and was last updated 1 month, 3 weeks ago by Whereas two threads reading from a file is thread-safe since the file isn’t being changed. Powershell:WPF, Multithreading, Oh My! While the 117ms difference won’t be noticeable if you only ran this code once, it would start to add up if run thousands of times. In the below example, a script block is defined that contains a short script that accepts a name and creates a file with that name. It then retrieves the output from the job and outputs it to the console. While multithreading has sounded like nothing but amazing so far, this isn’t quite the case. This command gets all of the attributes of your jobs. PowerShell 7 implemented Parallel Foreach but has not added a means to do Sync lock. Where PowerShell normally uses a single thread, there are many ways to use more than one to parallelize your code. While runspace pools work the same, below is an example of how to add an argument to a runspace pool. Below is an example of what it would look like for each. At some point, most people will run into a problem that a basic PowerShell script is just too slow to solve. The Parallel parameter of the ForEach keyword runs the commands in a ForEach script block once for each item in a specified collection.. Extremely smart and passionate people who could talk about PowerShell for days along with direct access to the PowerShell product team! To do this, you’d first define a trigger using New-JobTrigger and define the scheduled job like what is shown below. Now that the runspace is created, assign it to a PowerShell instance to run PowerShell code. To install the module, run the below command in an administrative PowerShell session. Yep, mutexes will work great inside of a PSJob as each PSJob that is created is under a new process. (max 2 MiB). Next, make sure your code is “thread-safe”. Use thread pools and DIY multi-threading. 0. This could slow down your code, or cause it to fail outright. Below is some code that can be used to compare the difference in speed between a PSJob and an RSJob. The recommended amount of threads in a runspace pool depends on the amount of tasks being performed, and the machine that is running the code. GitHub Gist: instantly share code, notes, and snippets. All PSJobs are in one of eleven states. Multithreading also introduces logging challenges. In the conversations following that post I had a reader submit a fairly nasty note saying that multithreading with jobs was in fact not real multithreading. Here is a simple example: 1..100 | ForEach-Object -ThrottleLimit 20 -Parallel { Start-Sleep -Seconds 1; $_ } In a normal ForEach-Object loop, this would take 100 seconds to execute. You can see in the below image that instead of the command taking five seconds to complete, it only took .15 seconds to start the job. In the example from the previous section, the PSjob created took about 150ms to bring up. This removes the file locking problem, but then you have many log files that you would have to sort through to figure out everything that happened. These are both great examples of where using more processing power would get your code to run faster. If there are ways for you to speed up your code before multithreading, they should be done first. The majority of the time it takes to spin up a runspace job is handled before any code has been added. This command is used to specify attributes of the scheduled job like the scriptblock that is going to be run and triggers created with the New-JobTrigger command. It has been nearly 5 years since I wrote my original article on multithreading where I used PowerShell jobs to run multiple items at a time. The biggest difference in runspaces and PSjobs is the time it takes to set up and break down each one. As you can see below there is a large speed difference since the RSJobs are still using runspaces below the covers. Using runspaces can be a daunting task at first since there is no more PowerShell command hand-holding. For Start-Job and Start-RSJob from the PoshRSJob module, you can use the ArgumentList parameter to provide a list of objects that will be passed as parameters to the scriptblock in the order you list them. There are many pros and cons to using multithreading, but if used correctly, you can drastically reduce the runtime of your code. The problem with PowerShell multithreading code that is not thread-safe is that you may get inconsistent results. You can create a scheduled job for this. Compare the code above to the below example. The PowerShell ForEach loop allows you to loop through a collection of items and perform a defined task (command) on each item. Each new job runs in its own Windows PowerShell.exe instance (session). Runspaces took me from about 90,000 rows per second to 230,000 rows per second on average. Then you will assign the new runspace to the new PowerShell instance and add code to that instance. When using BeginInvoke(), store the output to a variable as it will be required to see the status of the scriptblock in the runspace as shown below. It is very important to save the output of this to a variable so you have a way to end the runspace when it has completed, especially when you are expecting to output some sort of object or other types of output. Once you have the output from the BeginInvoke() stored to a variable, you can check that variable to see the status of the job as seen below in the IsCompleted property. PowerShell ForEach-Object Parallel Feature, ForEach-Object -Parallel is a new parameter set added to the existing PowerShell ForEach cmdlet. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy, 2021 Stack Exchange, Inc. user contributions under cc by-sa, https://stackoverflow.com/questions/16360019/how-do-i-add-multi-threading/16360328#16360328, if you want to get more advanced with controlling threads try this, fyi for those that don't know the command ForEach-Object has aliases % and foreach. Below is the time difference for running the two lines from above. Then when you scale the code up to 20 or 30 jobs, the likelihood of not having at least two of the jobs try to write at the same time goes way down.