Cannot extract enough nodes using SBS

[Carrieww]

Hi, I am working on movielens-1m dataset. SnowBallSampler will never stop when num_of_nodes is high (e.g. 50% of nodes) (I fixed the seed=2022 and k=50 by default). During debugging, I noticed self._queue in line 72 of snowballsampler.py is empty, as shown in the attachment. Therefore, the while loop will never stop. It would be nice to add an exception telling people that the sampler can only extract xxx nodes < num_of_nodes and advise people to increase the parameter k.

In my case, only 5049 nodes can be extracted using SnowBallSampler while num_of_nodes = 5200.