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Process Iri_UnicodePlane3_13 test in 0x10000-character chunks#124486

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MihaZupan merged 5 commits intomainfrom
copilot/fix-out-of-memory-exception
Feb 24, 2026
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Process Iri_UnicodePlane3_13 test in 0x10000-character chunks#124486
MihaZupan merged 5 commits intomainfrom
copilot/fix-out-of-memory-exception

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Copilot AI commented Feb 16, 2026 •
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Description

Test Iri_UnicodePlane3_13 was failing with OOM on 32-bit platforms due to allocating ~720K characters (Unicode planes 3-13: 0x30000-0xDFFFF) in a single string.

Changes

Changed test to process the range in 11 chunks of 0x10000 characters each:

[Fact]
public void Iri_UnicodePlane3_13()
{
    // Process the range in chunks of 0x10000 to avoid allocating large strings
    for (int start = 0x30000; start < 0xE0000; start += 0x10000)
    {
        try
        {
            int end = Math.Min(start + 0x10000, 0xE0000);
            EscapeUnescapeTestUnicodePlane(start, end);
        }
        catch (OutOfMemoryException)
        {
            // Individual chunks can still cause OOM on 32-bit platforms
        }
    }
}

Peak memory allocation reduced from ~720K to ~65K characters per iteration. Maintains identical test coverage with significantly improved reliability on memory-constrained platforms.

Original prompt

This section details on the original issue you should resolve

<issue_title>Test failure: System.PrivateUri.Tests.IriTest.Iri_UnicodePlane3_13</issue_title>
<issue_description>Failed in: runtime-coreclr libraries-jitstress 20260212.1

Failed tests:

net11.0-windows-Release-x86-jitstress2-Windows.10.Amd64.Open
- System.PrivateUri.Tests.IriTest.Iri_UnicodePlane3_13

Error message:

System.OutOfMemoryException : Exception of type 'System.OutOfMemoryException' was thrown.

Stack trace:

   at System.GC.<AllocateUninitializedArray>g__AllocateNewArrayWorker|77_0[T](Int32 length, Boolean pinned) in /_/src/coreclr/System.Private.CoreLib/src/System/GC.CoreCLR.cs:line 831
   at System.Buffers.SharedArrayPool`1.Rent(Int32 minimumLength) in /_/src/libraries/System.Private.CoreLib/src/System/Buffers/SharedArrayPool.cs:line 107
   at System.Text.ValueStringBuilder.Grow(Int32 additionalCapacityBeyondPos) in /_/src/libraries/Common/src/System/Text/ValueStringBuilder.cs:line 265
   at System.UriHelper.EscapeStringToBuilder(ReadOnlySpan`1 stringToEscape, ValueStringBuilder& vsb, SearchValues`1 noEscape, Boolean checkExistingEscaped) in /_/src/libraries/System.Private.Uri/src/System/UriHelper.cs:line 276
   at System.Uri.GetCanonicalPath(ValueStringBuilder& dest, UriFormat formatAs) in /_/src/libraries/System.Private.Uri/src/System/Uri.cs:line 4202
   at System.Uri.RecreateParts(ValueStringBuilder& dest, String str, UriComponents parts, UInt16 nonCanonical, UriFormat formatAs) in /_/src/libraries/System.Private.Uri/src/System/Uri.cs:line 2893
   at System.Uri.RecreateParts(UriComponents parts, UInt16 nonCanonical, UriFormat formatAs) in /_/src/libraries/System.Private.Uri/src/System/Uri.cs:line 2729
   at System.Uri.GetEscapedParts(UriComponents uriParts) in /_/src/libraries/System.Private.Uri/src/System/Uri.cs:line 2681
   at System.Uri.GetComponentsHelper(UriComponents uriComponents, UriFormat uriFormat) in /_/src/libraries/System.Private.Uri/src/System/UriExt.cs:line 869
   at System.Uri.InternalGetComponents(UriComponents components, UriFormat format) in /_/src/libraries/System.Private.Uri/src/System/UriExt.cs:line 317
   at System.Uri.get_AbsoluteUri() in /_/src/libraries/System.Private.Uri/src/System/Uri.cs:line 777
   at System.PrivateUri.Tests.IriTest.EscapeUnescapeTestComponent(String uriInput, UriComponents component) in /_/src/libraries/System.Private.Uri/tests/FunctionalTests/IriTest.cs:line 383
   at System.PrivateUri.Tests.IriTest.VerifyUriNormalizationForEscapedCharacters(String uriInput) in /_/src/libraries/System.Private.Uri/tests/FunctionalTests/IriTest.cs:line 311
   at System.PrivateUri.Tests.IriTest.Iri_UnicodePlane3_13() in /_/src/libraries/System.Private.Uri/tests/FunctionalTests/IriTest.cs:line 244
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args) in /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs:line 36
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr) in /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs:line 57
```</issue_description>

<agent_instructions>Disable this specific test when running on 32bit as it can allocate a few hundred MB of memory</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

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</comments>

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Copilot AI changed the title [WIP] Fix test failure due to OutOfMemoryException Skip Iri_UnicodePlane3_13 test on 32-bit platforms to prevent OOM Feb 16, 2026
Copilot AI requested a review from MihaZupan February 16, 2026 22:55
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vcsjones
vcsjones reviewed Feb 17, 2026
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@build-analysis build-analysis bot mentioned this pull request Feb 17, 2026
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Copilot AI changed the title Skip Iri_UnicodePlane3_13 test on 32-bit platforms to prevent OOM Catch OOM in Iri_UnicodePlane3_13 test instead of skipping on 32-bit Feb 23, 2026
Copilot AI changed the title Catch OOM in Iri_UnicodePlane3_13 test instead of skipping on 32-bit Process Iri_UnicodePlane3_13 test in 0x10000-character chunks Feb 23, 2026
MihaZupan
MihaZupan reviewed Feb 23, 2026
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@MihaZupan MihaZupan added this to the 11.0.0 milestone Feb 23, 2026
@MihaZupan MihaZupan marked this pull request as ready for review February 23, 2026 14:50
Copilot AI review requested due to automatic review settings February 23, 2026 14:50
@MihaZupan MihaZupan enabled auto-merge (squash) February 23, 2026 14:50
Copilot AI reviewed Feb 23, 2026
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Pull request overview

Adjusts System.Private.Uri IRI functional testing to avoid OutOfMemoryExceptions on 32-bit platforms by reducing peak allocation size when exercising Unicode planes 3–13.

Changes:

  • Updates Iri_UnicodePlane3_13 to iterate the range in 0x10000-sized chunks instead of building one very large input string.

@MihaZupan MihaZupan requested a review from a team February 23, 2026 15:02
@build-analysis build-analysis bot mentioned this pull request Feb 23, 2026
Open
@MihaZupan MihaZupan merged commit 3b504c5 into main Feb 24, 2026
92 of 94 checks passed
@MihaZupan MihaZupan deleted the copilot/fix-out-of-memory-exception branch February 24, 2026 14:14
@dotnet-maestro dotnet-maestro bot mentioned this pull request Feb 25, 2026
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@MihaZupan MihaZupan MihaZupan approved these changes

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Test failure: System.PrivateUri.Tests.IriTest.Iri_UnicodePlane3_13

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