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Fix Dask DBSCAN tree reduction #7398

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Merged
rapids-bot merged 2 commits into from
Oct 30, 2025
Merged

Fix Dask DBSCAN tree reduction #7398

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bb21def
Fix Dask DBSCAN tree reduction
viclafargue Oct 28, 2025
db3c69c
remove logging
viclafargue Oct 28, 2025
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5 changes: 3 additions & 2 deletions cpp/src/dbscan/mergelabels/tree_reduction.cuh
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Original file line number Diff line number Diff line change
Expand Up @@ -39,12 +39,13 @@ void tree_reduction(const raft::handle_t& handle,
const auto& comm = handle.get_comms();
int my_rank = comm.get_rank();
int n_rank = comm.get_size();
raft::comms::request_t request;

int s = 1;
while (s < n_rank) {
CUML_LOG_DEBUG("Tree reduction, s=", s);

raft::comms::request_t request;

// Find out whether the node is a receiver / sender / passive
bool receiver = my_rank % (2 * s) == 0 && my_rank + s < n_rank;
bool sender = my_rank % (2 * s) == s;
Expand All @@ -57,7 +58,7 @@ void tree_reduction(const raft::handle_t& handle,
comm.isend(labels, N, my_rank - s, 0, &request);
}

comm.waitall(1, &request);
if (receiver || sender) { comm.waitall(1, &request); }

if (receiver) {
CUML_LOG_DEBUG("--> Merge labels");
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8 changes: 6 additions & 2 deletions python/cuml/cuml/dask/cluster/dbscan.py
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Expand Up @@ -104,8 +104,12 @@ def fit(self, X, out_dtype="int32"):

data = self.client.scatter(X, broadcast=True)

comms = Comms(comms_p2p=True)
comms.init()
# Get the workers that actually hold the scattered data
who_has = self.client.who_has(data)
workers = list(who_has[data.key])

comms = Comms(comms_p2p=True, client=self.client)
comms.init(workers=workers)

# Get worker info to map workers to their RAFT ranks
worker_info = comms.worker_info(comms.worker_addresses)
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