GH-38281: [Go] Ensure CData imported arrays are freed on release#38314
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zeroshade merged 6 commits intoapache:mainfrom Oct 18, 2023
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GH-38281: [Go] Ensure CData imported arrays are freed on release#38314zeroshade merged 6 commits intoapache:mainfrom
zeroshade merged 6 commits intoapache:mainfrom
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| runtime.SetFinalizer(imp.data, func(arrow.ArrayData) { | ||
| defer C.free(unsafe.Pointer(arr)) | ||
| C.ArrowArrayRelease(arr) | ||
| if C.ArrowArrayIsReleased(arr) != 1 { | ||
| panic("did not release C mem") | ||
| } | ||
| }) |
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Might be a good idea to keep the finalizer in debug mode to assert that the ref count that's maintained manually via Retain/Release is indeed zero when the objected is not referenced anymore.
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We don't actually expose any API to externally check the current refcount on the objects so there's not really a way for the finalizer to check that. That's why I added the new tests to confirm that Release does actually free the memory, and users can use the CheckedAllocator if they want to ensure that things are being properly released
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Ahh. Makes sense. I do remember unit tests complaining about my refcounts when I was implementing ListView.
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After merging your PR, Conbench analyzed the 5 benchmarking runs that have been run so far on merge-commit 0428c5e. There were no benchmark performance regressions. 🎉 The full Conbench report has more details. It also includes information about 14 possible false positives for unstable benchmarks that are known to sometimes produce them. |
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Nov 13, 2023
apache#38314) ### Rationale for this change The usage of `SetFinalizer` means that it's not *guaranteed* that calling `Release()` on an imported Record or Array will actually free the memory during the lifetime of the process. Instead we can leverage a shared buffer count, atomic ref counting and a custom allocator to ensure proper and more timely memory releasing when importing from C Data interface. ### What changes are included in this PR? * Some simplifications of code to use `unsafe.Slice` instead of the deprecated handling of `reflect.SliceHeader` to improve readability * Updating tests using `mallocator.Mallocator` in order to easily allow testing to ensure that memory is being cleaned up and freed * Fixing a series of memory leaks subsequently found by the previous change of using the `mallocator.Mallocator` to track the allocations used for testing arrays. ### Are these changes tested? Yes, unit tests are updated and included. * Closes: apache#38281 Authored-by: Matt Topol <[email protected]> Signed-off-by: Matt Topol <[email protected]>
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apache#38314) ### Rationale for this change The usage of `SetFinalizer` means that it's not *guaranteed* that calling `Release()` on an imported Record or Array will actually free the memory during the lifetime of the process. Instead we can leverage a shared buffer count, atomic ref counting and a custom allocator to ensure proper and more timely memory releasing when importing from C Data interface. ### What changes are included in this PR? * Some simplifications of code to use `unsafe.Slice` instead of the deprecated handling of `reflect.SliceHeader` to improve readability * Updating tests using `mallocator.Mallocator` in order to easily allow testing to ensure that memory is being cleaned up and freed * Fixing a series of memory leaks subsequently found by the previous change of using the `mallocator.Mallocator` to track the allocations used for testing arrays. ### Are these changes tested? Yes, unit tests are updated and included. * Closes: apache#38281 Authored-by: Matt Topol <[email protected]> Signed-off-by: Matt Topol <[email protected]>
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Rationale for this change
The usage of
SetFinalizermeans that it's not guaranteed that callingRelease()on an imported Record or Array will actually free the memory during the lifetime of the process. Instead we can leverage a shared buffer count, atomic ref counting and a custom allocator to ensure proper and more timely memory releasing when importing from C Data interface.What changes are included in this PR?
unsafe.Sliceinstead of the deprecated handling ofreflect.SliceHeaderto improve readabilitymallocator.Mallocatorin order to easily allow testing to ensure that memory is being cleaned up and freedmallocator.Mallocatorto track the allocations used for testing arrays.Are these changes tested?
Yes, unit tests are updated and included.