Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Protect balanced k-means out-of-memory in some cases #1161

Merged
merged 5 commits into from
Jan 21, 2023
Merged

Protect balanced k-means out-of-memory in some cases #1161

Changes from 1 commit
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
10b4b80
Protect balanced k-means from allocating too large temporary buffers …
achirkin Jan 20, 2023
1ca100e
Add a note to the docstring regarding the updated behavior
achirkin Jan 20, 2023
2747745
Fix an edge case of very small dataset
achirkin Jan 20, 2023
882f045
Fix an edge case of very small dataset
achirkin Jan 20, 2023
d247dab
Fix typo bad conversion
achirkin Jan 20, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 17 additions & 14 deletions cpp/include/raft/spatial/knn/detail/ann_kmeans_balanced.cuh
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -880,8 +880,8 @@ auto build_fine_clusters(const handle_t& handle,
uint32_t n_clusters_done = 0;
for (uint32_t i = 0; i < n_mesoclusters; i++) {
uint32_t k = 0;
for (IdxT j = 0; j < n_rows; j++) {
if (labels_mptr[j] == (LabelT)i) { mc_trainset_ids[k++] = j; }
for (IdxT j = 0; j < n_rows && k < mesocluster_size_max; j++) {
if (labels_mptr[j] == LabelT(i)) { mc_trainset_ids[k++] = j; }
}
if (k != mesocluster_sizes[i])
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I suggest we omit warning when k is limited due to mesocluster_size_max.

Suggested change
if (k != mesocluster_sizes[i])
if (k != mesocluster_sizes[i] && k < mesocluster_size_max)

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think, it's better to leave the warning, because it also gives an extra information about which clusters are the offending clusters and emphasizes the importance of the previous warning about the unbalanced mesoclusters. In the logs, they go one after another and it's rather easy to see the link between the two.

RAFT_LOG_WARN("Incorrect mesocluster size at %d. %d vs %d", i, k, mesocluster_sizes[i]);
Expand All @@ -896,19 +896,13 @@ auto build_fine_clusters(const handle_t& handle,
"Number of fine clusters must be non-zero for a non-empty mesocluster");
}

utils::copy_selected((IdxT)mesocluster_sizes[i],
(IdxT)dim,
dataset_mptr,
mc_trainset_ids,
(IdxT)dim,
mc_trainset,
(IdxT)dim,
stream);
utils::copy_selected(
(IdxT)k, (IdxT)dim, dataset_mptr, mc_trainset_ids, (IdxT)dim, mc_trainset, (IdxT)dim, stream);
if (metric == raft::distance::DistanceType::L2Expanded ||
metric == raft::distance::DistanceType::L2SqrtExpanded) {
thrust::gather(handle.get_thrust_policy(),
mc_trainset_ids,
mc_trainset_ids + mesocluster_sizes[i],
mc_trainset_ids + k,
dataset_norm_mptr,
mc_trainset_norm);
}
Expand All @@ -917,7 +911,7 @@ auto build_fine_clusters(const handle_t& handle,
n_iters,
dim,
mc_trainset,
mesocluster_sizes[i],
k,
fine_clusters_nums[i],
mc_trainset_ccenters.data(),
mc_trainset_labels.data(),
Expand Down Expand Up @@ -1036,10 +1030,19 @@ void build_hierarchical(const handle_t& handle,
auto [mesocluster_size_max, fine_clusters_nums_max, fine_clusters_nums, fine_clusters_csum] =
arrange_fine_clusters(n_clusters, n_mesoclusters, n_rows, mesocluster_sizes);

if (mesocluster_size_max * n_mesoclusters > 2 * n_rows) {
RAFT_LOG_WARN("build_hierarchical: built unbalanced mesoclusters");
const auto mesocluster_size_max_balanced =
uint32_t(size_t{n_rows * 2lu} / std::max<size_t>(n_mesoclusters, 1lu));
if (mesocluster_size_max > mesocluster_size_max_balanced) {
RAFT_LOG_WARN(
"build_hierarchical: built unbalanced mesoclusters (max_mesocluster_size == %u > %u). "
"At most %u points will be used for training within each mesocluster. "
achirkin marked this conversation as resolved.
Show resolved Hide resolved
"Consider increasing the number of training iterations `n_iters`.",
mesocluster_size_max,
mesocluster_size_max_balanced,
mesocluster_size_max_balanced);
RAFT_LOG_TRACE_VEC(mesocluster_sizes, n_mesoclusters);
RAFT_LOG_TRACE_VEC(fine_clusters_nums.data(), n_mesoclusters);
mesocluster_size_max = mesocluster_size_max_balanced;
}

auto n_clusters_done = build_fine_clusters<T, IdxT, LabelT>(handle,
Expand Down