CODEWITHSUNDEEP
powershellmemory-leaksjobs
Bill Gillingham
Bill Gillingham

Reputation: 31

Why is remote Powershell job consuming so much host memory over time?

Using powershell, I am creating jobs to run a command block on remote servers. The command scans folders looking for certain files and returns the contents via the output buffer. So - I poll the job every so often (say 10s) - and use receive-job to clear the output buffer. Even then, the memory consumed on the host machine continues to grow by megabytes (memory consumption on client stays low throughout). I don't see anything in other job buffers (error, warning, etc.). The total amount of data received via receive-job ends up being maybe 300k... but the memory consumption is around 400mb. When I remove-job and force garbage collection, the memory is released.

The consumption is gradual, and the growth rate is fairly constant as the job runs. (well - it jumps 3-6mb every so often...)

Invoke-Command ComputerName=$vweb -ScriptBlock {
    param($domainsRoot, $filter, $newFileKey, $sitesList)
    Get-ChildItem -Path $domainsRoot -ErrorAction SilentlyContinue | Where-Object {$sitesList.Contains($_.Name)} |
        ForEach-Object -Process {               
            Get-ChildItem -Path (Join-Path (Join-Path $domainsRoot $_) "wwwroot/v/*") -filter $filter -recurse -ErrorAction SilentlyContinue |
                    ForEach-Object -Process {
                        Write-Output ($newFileKey + ($_.FullName.replace($domainsRoot,'')))
                        Write-Output (Get-Content -Path $_.FullName)
                    }
        }
} -ArgumentList $domainsRoot, $filter, $global:newFileKey, $sitesList -AsJob -JobName $($vweb)

The command block basically scans a folder ($domainsRoot) looking for target folders (found in $sitesList array) - scans a subfolder of that (wwwroot/v/*) looking for files that match a filter ($filter). (the purpose is to scan iis websites on multiple servers for *.asp files)

Is it something in my command block - or am I misunderstanding how jobs work?

ps version: 5.1.19041.1320, windows 10 host/clients

Upvotes: 2

Views: 306

Answers (1)

Bill Gillingham
Bill Gillingham

Reputation: 31

When you create a remote job, two jobs are created - one for the host and a child job (also on the host) for the remote job. When I used receive-job on the parent, I expected this to clear out all output streams (parent and child). It turned out that the child job still had a fully populated field $childJob.output.

I ended up using receive-job on the child job, and then immediately cleared its output using $childJob.output.clear().

In my tests, this didn't have any adverse affects - but, I wouldn't completely trust this method for more critical tasks without better testing.

After I did this, the memory consumption problem was resolved.

Upvotes: 1

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