diff --git a/src/neuron_proofreader/machine_learning/image_dataloader.py b/src/neuron_proofreader/machine_learning/image_dataloader.py
index 790969c3..b1fd6a5c 100644
--- a/src/neuron_proofreader/machine_learning/image_dataloader.py
+++ b/src/neuron_proofreader/machine_learning/image_dataloader.py
@@ -175,7 +175,7 @@ def create_mask(self, center, shape, node):
         subgraph = self.graph.rooted_subgraph(node, depth)
 
         # Annotate mask
-        mask = np.zeros(shape)
+        mask = np.zeros(shape, dtype=np.float32)
         #self.annotate_foreground(mask, nodes, offset, fill_val=0.5)  TEMP
         self.annotate_fragment(mask, subgraph, offset, fill_val=1)
         return mask
@@ -199,7 +199,7 @@ def read_image(self, center, shape):
         patch = self.img.read(center, shape)
         patch = np.minimum(patch, self.brightness_clip)
         patch = img_util.normalize(patch, percentiles=self.percentiles)
-        return patch
+        return patch.astype(np.float32)
 
     # --- Helpers ---
     def __getattr__(self, name):
diff --git a/src/neuron_proofreader/merge_proofreading/search_datasets.py b/src/neuron_proofreader/merge_proofreading/search_datasets.py
index 473685d1..52833cbf 100644
--- a/src/neuron_proofreader/merge_proofreading/search_datasets.py
+++ b/src/neuron_proofreader/merge_proofreading/search_datasets.py
@@ -11,8 +11,11 @@
 
 from abc import ABC, abstractmethod
 from concurrent.futures import FIRST_COMPLETED, ThreadPoolExecutor, wait
+from queue import Queue
+from threading import Thread
 from torch.utils.data import IterableDataset
 
+import itertools
 import networkx as nx
 import numpy as np
 import torch
@@ -59,27 +62,38 @@ def __init__(
 
     # --- Core routines ---
     def __iter__(self):
-        sites_generator = self._all_sites()
-        with ThreadPoolExecutor(max_workers=self.prefetch) as executor:
-            # Submit initial threads
-            pending = {}
-            for _ in range(self.prefetch):
-                self._submit(executor, sites_generator, pending)
-
-            # Process remaining jobs until complete
-            while pending:
-                done, _ = wait(pending.keys(), return_when=FIRST_COMPLETED)
-                for thread in done:
-                    site = pending.pop(thread)
-                    yield from self.get_input(site, *thread.result())
-                    self._submit(executor, sites_generator, pending)
-
-    def _submit(self, executor, sites_generator, pending):
-        try:
-            site = next(sites_generator)
-            pending[executor.submit(self.patch_loader, site)] = site
-        except StopIteration:
-            pass
+        patch_queue = Queue(maxsize=self.prefetch)
+        sentinel = object()
+    
+        def producer():
+            sites = self._all_sites()
+            with ThreadPoolExecutor(max_workers=self.prefetch) as executor:
+                futures = {}
+    
+                def fill():
+                    while len(futures) < self.prefetch:
+                        try:
+                            site = next(sites)
+                            futures[executor.submit(self.patch_loader, site)] = site
+                        except StopIteration:
+                            break
+    
+                fill()
+                while futures:
+                    done, _ = wait(futures, return_when=FIRST_COMPLETED)
+                    for f in done:
+                        patch_queue.put((futures.pop(f), f.result()))
+                    fill()
+    
+            patch_queue.put(sentinel)
+    
+        Thread(target=producer, daemon=True).start()
+    
+        while True:
+            item = patch_queue.get()
+            if item is sentinel:
+                break
+            yield from self.get_input(*item)
 
     def _all_sites(self):
         visited_ids = set()
@@ -231,29 +245,7 @@ def get_patch(self, nodes, img, offset):
             yield node, img[(slice(0, 2), *s)]
 
     def generate_patch_and_pc(self, nodes, img, offset):
-        # Initializations
-        label_mask = self.get_label_mask(nodes, img.shape, offset)
-        patch_centers = self.get_patch_centers(nodes) - offset
-
-        # Populate batch array
-        patches = np.empty((len(nodes), 2,) + self.patch_shape)
-        point_clouds = np.empty((len(nodes), 3, 3600), dtype=np.float32)
-        for i, (node, center) in enumerate(zip(nodes, patch_centers)):
-            s = img_util.get_slices(center, self.patch_shape)
-            patches[i, 0, ...] = img_util.normalize(img[s])
-            patches[i, 1, ...] = label_mask[s]
-
-            subgraph = self.graph.rooted_subgraph(node, self.subgraph_radius)
-            point_clouds[i] = subgraph_to_point_cloud(subgraph)
-
-        # Build batch dictionary
-        batch = ml_util.TensorDict(
-            {
-                "img": ml_util.to_tensor(patches),
-                "point_cloud": ml_util.to_tensor(point_clouds),
-            }
-        )
-        return nodes, batch
+        pass
 
     # --- Helpers ---
     def estimate_iterations(self):
@@ -276,7 +268,7 @@ def estimate_iterations(self):
 
         # Report results
         print("# Fragments:", n_fragments)
-        print(f"Total Cable Length: {total_cable_length / 1000:.2f}mm")
+        print(f"Total Cable Length: {total_cable_length / 10**5:.2f}cm")
         return int(total_cable_length / self.step_size)
 
 
@@ -310,9 +302,14 @@ def __init__(
         self.patch_loader = DetectionPatchLoader(self.graph, img_config)
         self.search_mode = "branching_nodes"
 
+    def estimate_iterations(self):
+        return len(self.branching_nodes())
+
     def generate_component_sites(self, root):
+        visited = set()
         for i, j in nx.dfs_edges(self.graph, source=root):
-            if self.degree[i] >= 3:
+            if self.degree[i] >= 3 and i not in visited:
+                visited.add(i)
                 yield i
 
     def get_patch(self, node, img):