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Demonstrate PowerShell memory leak with XmlSchemaSet
function cleanup() {
write-host "Cleaning up..."
remove-item $schemaFile
trap {
# The following was stolen from
Add-Type -Language CSharp -TypeDefinition @'
public class NullString {
public override string ToString() {
return null;
$null_for_dotnet_string = New-Object -TypeName NullString;
<schema xmlns="" 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"/>
$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)
# ATTEMPT: [void] $schemaSet.RemoveRecursive($schema)
# ATTEMPT: remove-variable schema
} catch {
write-host "$($schemaFileName): Exception: $_"
# ATTEMPT: remove-variable reader
# ATTEMPT: remove-variable schemaSet
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