The PowerShell Guy

and mine

I did go on from Karl's last post Fast New PSCustomObject. where he used a HashTable to add the Properties and questioned the performance, so I converted his sample to a CTP2 Add-Type example and tested generating the Hashtable with an added method to ObjGen to create a HashTable, so to get a nice way in code to create the HashTable that is still performant.

I got some nice results again :

1. Creating HashTables with @{} does not preserve order (know issue) see output below
2. creating a HashTable from objGen and adding properties to it slows down considerable
3. Using the PowerShell Shortcut, just assigning the values to non existing properties (very convenient ) , is actually faster as using the Add method  and brings back speed to comparable speed with Karl's method :

Especialy 3 item did surprise and pleasure me

As you can see from the output above just assigning the not existing properties in the HashTable is faster as using the Add method, so this method looks better in Code AND is faster so a win-win situation

Lesson learned, convenient shortcuts are not always slower  

My testing code :

$class = @"
public static class ObjGen
{

  public static System.Collections.Hashtable GetHashTable (){return new System.Collections.Hashtable(); }

  public static System.Management.Automation.PSObject GetPSObject( System.Collections.Hashtable noteproperties )
  {
    System.Management.Automation.PSObject obj = new System.Management.Automation.PSObject();
    if (noteproperties != null) 
    {
      foreach(System.Collections.DictionaryEntry item in noteproperties)
      {
        obj.Properties.Add(new System.Management.Automation.PSNoteProperty((string)item.Key,item.Value)); 
      }
    }
    return obj;
  }
}
"@

add-type $class

. c:\powershell\Get-PerformanceHistory.ps1

1..50000 |% {[ObjGen]::GetPSObject($null)}
1..50000 |% {new-object PSObject}

.{
  [ObjGen]::GetPSObject(@{name="karl";age=31;now = [datetime]::Now}) | out-host

  $p = [ObjGen]::GetHashTable()
  $p.Add("name","karl")
  $p.add("age",31)
  $p.add("now",[datetime]::Now)
  [ObjGen]::GetPSObject($p) | out-host

  $p = [ObjGen]::GetHashTable()
  $p.name = "karl"
  $p.age = 31
  $p.now = [datetime]::Now
  [ObjGen]::GetPSObject($p) | out-host
}

1..50000 |% {[void][ObjGen]::GetPSObject(@{name="karl";age=31;now = [datetime]::Now})}

1..50000 |% {
  $p = [ObjGen]::GetHashTable()
  $p.Add("name","karl")
  $p.add("age",31)
  $p.add("now",[datetime]::Now)
  [void][ObjGen]::GetPSObject($p)
}

1..50000 |% {
  $p = [ObjGen]::GetHashTable()
  $p.name = "karl"
  $p.age = 31
  $p.now = [datetime]::Now
  [void][ObjGen]::GetPSObject($p)
}

Get-PerformanceHistory 6

# h | select com*,{[datetime]$_.EndExecutionTime - [datetime]$_.StartExecutionTime}

Also testing showed the HashTable method of Objgen is realy not needed as the @{} construct for hashtables PowerShell  is also faster as this method.

Greetings /\/\o\/\/