Historically Speaking

So I've recently had a need to begin using Slack. I started out using a web browser, but since there is a Windows client I decided to give it a go. This article isn't about Slack as much as what I was curious about and how I decided to tackle the problem.

I had read a few comments about the performance of the Slack client, although they may have been in reference to using a web browser, but it actually doesn't matter. Instead I thought, "How can I get some historical data?" You probably have similar needs for things like processes or disk space. Since I was interested in memory utilization I could have used performance counters, and perhaps I'll write about that eventually, but for now I had a simple one line command that gave me the pieces of information I wanted to track.

Get-Process Slack | measure -Property WS -sum | Select Count,Sum

Getting process data (Image Credit: Jeff Hicks)

What I wanted was a way to take that snapshot repeatedly throughout the day and record the results. I decided to use a PowerShell scheduled job.

I wanted a repeating task and in my case I decided to only have it repeat for an 8 hour time span. I used a hashtable of parameters to splat to New-JobTrigger.

$paramHash = @{
RepetitionInterval = (New-TimeSpan -Minutes 30)
RepetitionDuration = (New-Timespan -hours 8)
at = (Get-Date).AddMinutes(1)
Once = $True
}

$Trigger = New-JobTrigger @paramHash

I elected to kick off the job one minute from the time I created the trigger. I could have used a scriptfile for my command which I expanded to export the results to a CSV file with a little additional information.

$sb = {
Param([string]$Path)

Get-Process Slack | measure -Property WS -sum |
Select @{Name="Computername";Expression={$env:computername}},
@{Name="Date";Expression={Get-Date}},Count,Sum |
Export-CSV $path -Append -NoTypeInformation
}

All that remains is to create the scheduled job with Register-ScheduledJob.

$path = "C:\work\slackhistory.csv"
$paramHash = @{
Name = 'SlackHistory'
Trigger = $Trigger
MaxResultCount = 4
ScriptBlock = $sb
ArgumentList = $path
}

Register-ScheduledJob @paramHash

Throughout the day, PowerShell added data to my CSV file.

The data csv file (Image Credit: Jeff Hicks)

If you noticed, I suppressed type information. This was so I could easily import the CSV into Excel and do some charting.

Charting the data in Excel (Image Credit: Jeff Hicks)

I formatted a few columns to make a nicer graph. Although I certainly could have formatted values like the WS sum in MB in PowerShell to begin with.

My techniques here are admittedly a little ad-hoc and perhaps not completely ready for an enterprise wide data gathering system, certainly of the "poor man's" flavor. But I hope you see how easy it is to combine PowerShell and scheduled tasks to get the job done.

You probably have questions, so feel free to ask in the comments.

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