Demonstrate PowerShell memory leak with XmlSchemaSet

repro-xmlschemaset-memoryleak.ps1

function cleanup() {
	write-host "Cleaning up..."
	remove-item $schemaFile
	break
}

trap {
	cleanup
}

# The following was stolen from http://powershellquiz.com/post/10429186577/a4-one-bit-of-difference
Add-Type -Language CSharp -TypeDefinition @'
public class NullString {
    public override string ToString() {
        return null;
    }
}
'@
$null_for_dotnet_string = New-Object -TypeName NullString;


$TEST_SCHEMA = @'
<schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:x">
	<element name="a" type="string"/>
	<element name="b" type="string"/>
	<element name="c" type="string"/>
	<element name="d" type="string"/>
	<element name="e" type="string"/>
	<element name="f" type="string"/>
	<element name="A" type="string"/>
	<element name="B" type="string"/>
	<element name="C" type="string"/>
	<element name="D" type="string"/>
	<element name="E" type="string"/>
	<element name="F" type="string"/>
</schema>
'@

$schemaFileName = [System.IO.Path]::GetTempFileName()

$TEST_SCHEMA > $schemaFileName

$N = 100000

1..$N |% {

	if ($_ % 100 -eq 0) { write-host -nonewline '.' }

	$schemaSet = new-object -typename System.Xml.Schema.XmlSchemaSet

	$dummy = register-objectevent $schemaSet ValidationEventHandler -MessageData $schemaFileName -Action {
		$a = $args[1]
		$e = $a.Exception
		$topLevelFileName = $event.MessageData
		write-host "$($topLevelFileName): $($a.Severity) in $($e.SourceUri) at line $($e.LineNumber) column $($e.LinePosition): $($e.Message)"
	}

	try {
		$reader = [System.Xml.XmlReader]::Create($schemaFileName)

		# Passing $null to a .NET method which expects a string
		# doesn't work: PowerShell passes an empty string instead,
		# which has a different (and incorrect) meaning for Add().
		[void] $schemaSet.Add($null_for_dotnet_string, $reader)
		# ATTEMPT: $schema = $schemaSet.Add($null_for_dotnet_string, $reader)

		$reader.Close()

		$schemaSet.Compile()

		# ATTEMPT: [void] $schemaSet.RemoveRecursive($schema)
		# ATTEMPT: remove-variable schema
	} catch {
		write-host "$($schemaFileName): Exception: $_"
	}

	# ATTEMPT: remove-variable reader
	# ATTEMPT: remove-variable schemaSet 
}

write-host