remove gc collect again for now

Author: albertz

users/zeyer/experiments/exp2024_04_23_baselines/ctc_recog_ext.py

@@ -457,7 +457,6 @@ def model_recog_flashlight(
         out_spatial_dim,
         final beam_dim
     """
-    import gc
     from dataclasses import dataclass
     import torch
     from flashlight.lib.text.decoder import LM, LMState
@@ -598,7 +597,9 @@ def _cache_maybe_free_memory(self):
                     if used_mem / total_mem < self._max_used_mem_fraction:
                         break
                     # Check again after trying to empty the cache.
-                    gc.collect()
+                    # Note: gc.collect() is problematic here because of how Flashlight handles the states:
+                    # We have millions of Python objects in the mapping_states dict,
+                    # which takes a very long time to go through.
                     torch.cuda.empty_cache()
                     used_mem = torch.cuda.memory_reserved(dev)
                     if used_mem / total_mem < self._max_used_mem_fraction: