question

Since you've changed both the O/S and PowerShell it's kinda hard to say!

However, if you're creating an array of 300K files and then processing the contents of the array, perhaps simply piping the results of the (I assume) Get-ChildItem into the Foreach-Object (If that's what you're using) might cure the problem.

OTOH, of you're using something like ForEach ($file in $array ){...} you'd have to change it to $array | Foreach-Object {...} and either change the existing references to the $file variable to $, or make the first statement in the ForEach-Object block something like $file = $, allowing you to avoid changing possibly multiple line of code.

Thanks for the reply, but I got this fixed.

The first thing I tried was to use [System.GC]::Collect(). I read so much about this and was amazed at all the differing information/opions people were providing whether to use this or not. In the if loop, I kept a counter of files read and would call Collect every 1000 files. Unfortunately, this had no effect at all.

I then just upgraded PowerShell to v5.1 from this link:
https://download.microsoft.com/download/6/F/5/6F5FF66C-6775-42B0-86C4-47D41F2DA187/Win8.1AndW2K12R2-KB3191564-x64.msu

Now everything works as before. I have to assume that it was something to do with PS v4, perhaps even a memory leak, as it works pefectly in v3 and v5.1.

If you'd accumulated 300K file objects in an array and then began processing them doing a garbage collection wouldn't have much of an effect. Doing a garbage collection after releasing the array (e.g. $array = $null, or $array = @()) might be beneficial, but only if there was a lot going on in the script after you're done with the array. Also possible is the removal from the array of the item just processed in the loop. After, say, removing 1000 items from the array you'd release some memory -- but at the expense of resizing the array repeatedly, and that would also consume memory and significant time,

That's one of the reasons I suggested piping the list of files directly into the loop rather than storing the results in an array. There's no large amount of storage consumed by the array.

I was going to suggest upgrading to release 5.1, but you didn't mention if there was any dependence on a particular version of PowerShell so I assumed(!) that there might be.

Hi, given that this post has been quiet for a while, this is a quick question and answer. Has your question been solved? If so, please mark it as an answer so that users with the same question can find and get help.
:)