With h2o.prcomp(d, k=605, pca_method="Randomized") (d is a matrix of 1000 rows, 784 columns, of which 605 are non-const columns, i.e. it is the first 1000 rows of MNIST data.):
After being frustrated with it taking so long, and not knowing how long it might still run for (see bug #3322) I clicked stop from within RStudio. According to R it is stopped. However the water meter tells me 1 core is still maxed out, and `top` confirms that h2o is still running.
My guess is that it is because h2o.prcomp, with "Randomized" (or "Power" or "GLRM") first makes a PCA model, then makes an SVD model, and that the abort kills the PCA model, but it doesn't kill the SVD model?
I've marked this as a critical bug because the only way to stop that thread working was to kill the whole java process , this killing the cluster and losing all my models and data.