Ensure UpstreamResourceAdaptor is not cleared by the Python GC
#1170
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vyasr
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Nov 30, 2022
vyasr
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Nov 30, 2022
harrism
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Dec 1, 2022
Co-authored-by: Vyas Ramasubramani <vyas.ramasubramani@gmail.com>
…wina/rmm into upstream-resource-adaptor-no-gc-clear
…resource-adaptor-no-gc-clear
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shwina
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Dec 19, 2022
…idsai#1170) Closes rapidsai#1169. Essentially, we are running into the situation described in https://cython.readthedocs.io/en/latest/src/userguide/extension_types.html#disabling-cycle-breaking-tp-clear with `UpstreamResourceAdaptor`. The solution is to prevent clearing of `UpstreamResourceAdaptor` objects by decorating them with `no_gc_clear`. Cython calls out the following: > If you use no_gc_clear, it is important that any given reference cycle contains at least one object without no_gc_clear. Otherwise, the cycle cannot be broken, which is a memory leak. The other object in RMM that we mark `@no_gc_clear` is `DeviceBuffer`, and a `DeviceBuffer` can keep a reference to an `UpstreamResourceAdaptor`. But, an `UpstreamResourceAdaptor` cannot keep a reference to a `DeviceBuffer`, so instances of the two cannot form a reference cycle AFAICT. Authors: - Ashwin Srinath (https://github.com/shwina) Approvers: - Vyas Ramasubramani (https://github.com/vyasr) - Mark Harris (https://github.com/harrism) URL: rapidsai#1170
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Closes #1169.
Essentially, we are running into the situation described in https://cython.readthedocs.io/en/latest/src/userguide/extension_types.html#disabling-cycle-breaking-tp-clear with
UpstreamResourceAdaptor.The solution is to prevent clearing of
UpstreamResourceAdaptorobjects by decorating them withno_gc_clear.Cython calls out the following:
The other object in RMM that we mark
@no_gc_clearisDeviceBuffer, and aDeviceBuffercan keep a reference to anUpstreamResourceAdaptor. But, anUpstreamResourceAdaptorcannot keep a reference to aDeviceBuffer, so instances of the two cannot form a reference cycle AFAICT.