Segfault in METIS

[aaron-skydio]

segfault in metis for exactly five optimized variables :exploding_head:

best example I have currently, just dealing with two-vectors. the commented out jacobians/hessians look fine to me. any other chain length seems to work fine

import functools
import numpy as np

from symforce import geo
from symforce import sympy as sm
from symforce.opt.factor import Factor
from symforce.opt.optimizer import Optimizer
from symforce.values import Values

import sym

def between(x: geo.V2, y: geo.V2) -> geo.V2:
    return x - y

# if this is 4 or 6 or any other number I tried so far, it works
num_samples = 5
x_keys = [f"x{i}" for i in range(num_samples)]

values = Values()
for i in range(num_samples):
    values[x_keys[i]] = np.array([1, 2])
print(values)

factors = []

for i in range(num_samples - 1):
    factor = Factor(keys=[x_keys[i], x_keys[i + 1]], residual=between)
    factors.append(factor)

    # factor._generate_python_function(optimized_keys=factor.keys)
    # res, jac, hes, rhs = factor.generated_residual(values[x_keys[i]], values[x_keys[i + 1]])
    # print(jac)
    # import ipdb; ipdb.set_trace()

x_prior = geo.V2(1, 0)
prior_factor = Factor(
    keys=[x_keys[0]], name="prior", residual=functools.partial(between, y=x_prior)
)
factors.append(prior_factor)

# prior_factor._generate_python_function(prior_factor.keys)
# res, jac, hes, rhs = prior_factor.generated_residual(values[xs[0]])
# print(jac)

optimizer = Optimizer(factors=factors, optimized_keys=values.keys(), params=Optimizer.Params())

# segfault here in metis computing ordering
result = optimizer.optimize(values)

print(f"x_prior: {x_prior.T}")
print(result.initial_values)
print(result.optimized_values)
print(f"num iters: {len(result.iteration_stats)}")
print(f"final error: {result.error()}")

I added a print in SparseCholeskySolver<MatrixType, UpLo>::ComputePermutationMatrix, just before the failing line to ordering_(A_selfadjoint, invpermutation) to convert to dense and print:

Dense A_selfadjoint:
 1  0 -1  0  0  0  0  0  0  0
 0  1  0 -1  0  0  0  0  0  0
-1  0  1  0 -1  0  0  0  0  0
 0 -1  0  1  0 -1  0  0  0  0
 0  0 -1  0  1  0 -1  0  0  0
 0  0  0 -1  0  1  0 -1  0  0
 0  0  0  0 -1  0  1  0 -1  0
 0  0  0  0  0 -1  0  1  0 -1
 0  0  0  0  0  0 -1  0  1  0
 0  0  0  0  0  0  0 -1  0  1

with num_samples = 6, structure is the same

Dense A_selfadjoint:
 1  0 -1  0  0  0  0  0  0  0  0  0
 0  1  0 -1  0  0  0  0  0  0  0  0
-1  0  1  0 -1  0  0  0  0  0  0  0
 0 -1  0  1  0 -1  0  0  0  0  0  0
 0  0 -1  0  1  0 -1  0  0  0  0  0
 0  0  0 -1  0  1  0 -1  0  0  0  0
 0  0  0  0 -1  0  1  0 -1  0  0  0
 0  0  0  0  0 -1  0  1  0 -1  0  0
 0  0  0  0  0  0 -1  0  1  0 -1  0
 0  0  0  0  0  0  0 -1  0  1  0 -1
 0  0  0  0  0  0  0  0 -1  0  1  0
 0  0  0  0  0  0  0  0  0 -1  0  1

GDB backtrace shows the segfault in libmetis__genmmd

[hayk-skydio]

@aaron-skydio I notice a bunch of these old tickets are Done in the project but still Open here? Is it a manual process to do both?

[aaron-skydio]

Aah, I'll go through and fix them. It's automated in the reverse direction (closing the issue marks as done in the project), but there's seemingly no way to have marking as done automatically close the issue yet