Remove `GlobalArray` and `GlobalVector`.

glotzerlab / hoomd-blue

Molecular dynamics and Monte Carlo soft matter simulation on GPUs.

http://glotzerlab.engin.umich.edu/hoomd-blue

BSD 3-Clause "New" or "Revised" License

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Remove `GlobalArray` and `GlobalVector`. #1938

Closed joaander closed 1 week ago

joaander commented 1 week ago

Description

Remove the now unused GlobalArray and GlobalVector classes.

Motivation and context

Unused code adds needless complication the codebase.

How has this been tested?

CI checks.

Checklist:

[x] I have reviewed the Contributor Guidelines.
[x] I agree with the terms of the HOOMD-blue Contributor Agreement.
[x] My name is on the list of contributors (sphinx-doc/credits.rst) in the pull request source branch.
[x] I have summarized these changes in CHANGELOG.rst following the established format.

joaander commented 1 week ago

@mphoward FYI, GlobalArray apparently disabled the check that prevented overlapping ArrayHandles on the same GPUArray - even when it masqueraded as GPUArray. Expect to trigger this exception when your external components when they are built against trunk-major (or 5.0 after release): https://github.com/glotzerlab/hoomd-blue/blob/ec0b84cdf49987f9d6fdd5d1f6d4bfa216edbfc7/hoomd/GPUArray.h#L1172-L1176

See the individual commits on this PR for methods to avoid the exception.

mphoward commented 1 week ago

Got it, thanks! I can't remember whether we are actually using GlobalArray anywhere or if we stuck with GPUArray, but this simplification of the codebase so we don't have to worry about that choice will be very helpful.

joaander commented 1 week ago

Got it, thanks! I can't remember whether we are actually using GlobalArray anywhere or if we stuck with GPUArray, but this simplification of the codebase so we don't have to worry about that choice will be very helpful.

ParticleData, NeighborList, ParticleGroup and other core classes were using GlobalArray. If you use any of these classes in your components then you were using GlobalArray unknowingly. There are seeming weird issues that occur, like you can't do

for (unsigned int i = 0; i < m_group->getNumMembers();

if you have a handle to the tags array above the for loop because getNumMembers might acquire the tags array when it rebuilds the group.

mphoward commented 1 week ago

If you use any of these classes in your components then you were using GlobalArray unknowingly.

Got it, yeah, that makes sense. I'm sure we will run into at least some of these issues then.