Powershell Find and Replace Loop, OutOfMemoryException - powershell

Question

I have a working powershell script to find and and replace a few different strings with a new string in thousands of files, without changing the modified date on the files. In any given file there could be hundreds of instances of said strings to replace. The files themselves aren't very large and probably range from 1-50MB (a quick glance at the directory I am testing with shows the largest as ~33MB).
I'm running the script inside a Server 2012 R2 VM with 4 vCPUs and 4GB of RAM. I have set the MaxMemoryPerShellMB value for Powershell to 3GB. As mentioned previously, the script works, but after 2-4 hours powershell will start throwing OutOfMemoryExceptions and crash. The script is 'V2 friendly' and I haven't adopted it to V3+ but I doubt that matters too much.
My question is whether or not the script can be improved to prevent/eliminate the memory exceptions I am running into at the moment. I don't mind if it runs slower, as long as it can get the job done without having to check back every couple of hours and restart it.
$i=0
$all = Get-ChildItem -Recurse -Include *.txt
$scriptfiles = Select-String -Pattern string1,string2,string3 $all
$output = "C:\Temp\scriptoutput.txt"
foreach ($file in $scriptFiles)
{
$filecreate=(Get-ChildItem $file.Path).creationtime
$fileaccess=(Get-ChildItem $file.Path).lastaccesstime
$filewrite=(Get-ChildItem $file.Path).lastwritetime
"$file.Path,Created: $filecreate,Accessed: $fileaccess,Modified: $filewrite" | out-file -FilePath $output -Append
(Get-Content $file.Path) | ForEach-Object {$_ -replace "string1", "newstring" `
-replace "string2", "newstring" `
-replace "string3", "newstring"
} | Set-Content $file.Path
(Get-ChildItem $file.Path).creationtime=$filecreate
(Get-ChildItem $file.Path).lastaccesstime=$fileaccess
(Get-ChildItem $file.Path).lastwritetime=$filewrite
$filecreate=(Get-ChildItem $file.Path).creationtime
$fileaccess=(Get-ChildItem $file.Path).lastaccesstime
$filewrite=(Get-ChildItem $file.Path).lastwritetime
"$file.Path,UPDATED Created: $filecreate,UPDATED Accessed: $fileaccess,UPDATED Modified: $filewrite" | out-file -FilePath $output -Append
$i++}
Any comments, criticisms, and suggestions welcomed.
Thanks

Answer 1

Biggest issue I can see is that you are repeatedly getting the file for every property you are querying. Replace that with one call per loop pass and save it to be used during the pass. Also Out-File is one of the slower methods of outputting data to file.
$output = "C:\Temp\scriptoutput.txt"
$scriptfiles = Get-ChildItem -Recurse -Include *.txt |
Select-String -Pattern string1,string2,string3 |
Select-Object -ExpandProperty Path
$scriptfiles | ForEach-Object{
$file = Get-Item $_
# Save currrent file times
$filecreate=$file.creationtime
$fileaccess=$file.lastaccesstime
$filewrite=$file.lastwritetime
"$file,Created: $filecreate,Accessed: $fileaccess,Modified: $filewrite"
# Update content.
(Get-Content $file) -replace "string1", "newstring" `
-replace "string2", "newstring" `
-replace "string3", "newstring" | Set-Content $file
# Write all the original times back.
$file.creationtime=$filecreate
$file.lastaccesstime=$fileaccess
$file.lastwritetime=$filewrite
# Verify the changes... Should not be required but it is what you were doing.
$filecreate=$file.creationtime
$fileaccess=$file.lastaccesstime
$filewrite=$file.lastwritetime
"$file,UPDATED Created: $filecreate,UPDATED Accessed: $fileaccess,UPDATED Modified: $filewrite"
} | Set-Content $output
Not tested but should be fine.
Depending on what you replacements are actually like you could probably save some time there as well. Test first before running in production obviously.
I remove the counter you had since it appeared nowhere in the code.
Your logging could easily be csv based since you have all the object ready to go but I just want to be sure we are one the right track before we go to far.