[Efficiency Improver] perf: reduce allocations in BFSTestNodeVisitor path tracking and WrappedName building#7836
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Evangelink merged 3 commits intoApr 27, 2026
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…teWrappedName - Replace StringBuilder in the BFS queue with string, eliminating one StringBuilder allocation per test node during tree traversal. Each node's full path is now an immutable string shared directly with child nodes as their base path. - Replace HashSet<PlatformTestNodeUid> with HashSet<string> for UID filter lookups. This avoids allocating a temporary PlatformTestNodeUid wrapper object on every node lookup in the HashSet. - Simplify CreateWrappedName in TestArgumentsManager to a conditional string.Concat, removing a StringBuilder allocation per argument entry. Proxy metric: heap allocations per test node during BFS traversal. Before: 1 StringBuilder + 1 string per node (path) + 1 PlatformTestNodeUid per node (filter lookup). After: 1 string per node (path), no PlatformTestNodeUid per lookup. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
This PR reduces heap allocations in MSTest.Engine’s test-node discovery/execution pipeline by simplifying per-node path tracking in BFSTestNodeVisitor and by removing StringBuilder usage in argument display-name wrapping.
Changes:
- Replace per-node
StringBuilderpath propagation inBFSTestNodeVisitorwith immutablestringpath tracking. - Avoid per-lookup
PlatformTestNodeUidwrapper allocations by switching UID filter membership checks toHashSet<string>. - Simplify
TestArgumentsManager.CreateWrappedNameto usestring.Concatinstead ofStringBuilder.
Show a summary per file
| File | Description |
|---|---|
| src/Adapter/MSTest.Engine/Engine/BFSTestNodeVisitor.cs | Removes per-node StringBuilder allocations in BFS traversal and reduces UID-filter lookup allocations by using string values directly. |
| src/Adapter/MSTest.Engine/Engine/TestArgumentsManager.cs | Removes StringBuilder allocation from wrapped-name formatting for argument fragments. |
Copilot's findings
- Files reviewed: 2/2 changed files
- Comments generated: 2
This was referenced Apr 26, 2026
…deVisitor Agent-Logs-Url: https://github.com/microsoft/testfx/sessions/c99d957f-6c20-4942-988b-5c1977ecef1d Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>
…nd cache PathSeparator as string field Agent-Logs-Url: https://github.com/microsoft/testfx/sessions/eb488e40-99da-4224-81ee-95f9c0e4dc4b Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>
JanKrivanek
approved these changes
Apr 27, 2026
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|
Btw. PR description got likely half eaten out |
Evangelink
deleted the
efficiency/bfstestnode-string-path-tracking-f474c342a1a32973
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This was referenced Apr 28, 2026
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Replace StringBuilder in the BFS queue with string, eliminating one StringBuilder allocation per test node during tree traversal. Each node's full path is now an immutable string shared directly with child nodes as their base path.
Replace HashSet with HashSet for UID filter lookups. This avoids allocating a temporary PlatformTestNodeUid wrapper object on every node lookup in the HashSet.
Simplify CreateWrappedName in TestArgumentsManager to a conditional string.Concat, removing a StringBuilder allocation per argument entry.
Proxy metric: heap allocations per test node during BFS traversal. Before: 1 StringBuilder + 1 string per node (path) + 1 PlatformTestNodeUid
per node (filter lookup).
After: 1 string per node (path), no PlatformTestNodeUid per lookup.
Fixes #7828