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[mono][interp] Fix various leaks, primarily around dynamic methods - #119176
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For dynamic methods, imethod_alloc0 allocates from the dynamic method's mempool which is freed when the method is collected. We were previously allocating only from the global memory manager.
BrzVlad
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kotlarmilos, steveisok and vitek-karas
as code ownersAugust 28, 2025 15:15
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Tagging subscribers to this area: @BrzVlad, @kotlarmilos |
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Pull Request Overview
This PR addresses memory leaks in the Mono interpreter, particularly for dynamic methods. The main focus is on properly freeing method headers created during inlining operations and making various data structures associated with dynamic methods freeable.
Key changes:
- Tracks and frees method headers created during inlining to prevent memory leaks
- Changes memory allocation strategy for offset arrays to use freeable memory
- Implements cleanup of tiering data and patch sites when dynamic methods are freed
Reviewed Changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| src/mono/mono/mini/interp/transform.h | Adds headers_to_free field to track method headers for cleanup |
| src/mono/mono/mini/interp/transform.c | Implements header tracking and changes allocation strategy for offset arrays |
| src/mono/mono/mini/interp/tiering.h | Adds function declaration for clearing data items patch sites |
| src/mono/mono/mini/interp/tiering.c | Implements cleanup logic for patch sites when dynamic methods are freed |
| src/mono/mono/mini/interp/interp.c | Integrates patch site cleanup into method freeing process |
| src/mono/mono/mini/interp/interp-internals.h | Adds n_data_items field to track data item count for cleanup |
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Previously we were registering imethod locations from these data items in order for them to be patched once a method is tiered up. Because of this registering, the data item had to always be around. We now free the data item for dynamic methods and also we deregister the patch locations when freeing such a method.
We add them to a list for later freeing. This uses the same pattern as jit.
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kotlarmilos
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Aug 29, 2025
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srxqds
commented
Sep 1, 2025
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can you backport to release/9.0 and release/10.0 branch |
BrzVlad added a commit
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Sep 11, 2025
…otnet#119176) * [mono][interp] Fix leaking of compilation data For dynamic methods, imethod_alloc0 allocates from the dynamic method's mempool which is freed when the method is collected. We were previously allocating only from the global memory manager. * [mono][interp] Stop leaking data items Previously we were registering imethod locations from these data items in order for them to be patched once a method is tiered up. Because of this registering, the data item had to always be around. We now free the data item for dynamic methods and also we deregister the patch locations when freeing such a method. * [mono][interp] Free headers allocated for inlined methods We add them to a list for later freeing. This uses the same pattern as jit. * [mono][interp] Skip interp free for methods not yet compiled
BrzVlad added a commit
to BrzVlad/runtime
that referenced
this pull request
Sep 12, 2025
…otnet#119176) * [mono][interp] Fix leaking of compilation data For dynamic methods, imethod_alloc0 allocates from the dynamic method's mempool which is freed when the method is collected. We were previously allocating only from the global memory manager. * [mono][interp] Stop leaking data items Previously we were registering imethod locations from these data items in order for them to be patched once a method is tiered up. Because of this registering, the data item had to always be around. We now free the data item for dynamic methods and also we deregister the patch locations when freeing such a method. * [mono][interp] Free headers allocated for inlined methods We add them to a list for later freeing. This uses the same pattern as jit. * [mono][interp] Skip interp free for methods not yet compiled Fix attempt to free tiering data when tiering is disabled (dotnet#119294)
BrzVlad added a commit
to BrzVlad/runtime
that referenced
this pull request
Sep 23, 2025
…otnet#119176) * [mono][interp] Fix leaking of compilation data For dynamic methods, imethod_alloc0 allocates from the dynamic method's mempool which is freed when the method is collected. We were previously allocating only from the global memory manager. * [mono][interp] Stop leaking data items Previously we were registering imethod locations from these data items in order for them to be patched once a method is tiered up. Because of this registering, the data item had to always be around. We now free the data item for dynamic methods and also we deregister the patch locations when freeing such a method. * [mono][interp] Free headers allocated for inlined methods We add them to a list for later freeing. This uses the same pattern as jit. * [mono][interp] Skip interp free for methods not yet compiled Fix attempt to free tiering data when tiering is disabled (dotnet#119294)
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Free method headers created for inlining. Make some offsets arrays used by dynamic interp methods freeable. Make tiering data and the data items for dynamic methods freeable.