test: add URL image loading comparison script

studio/tests/test_url_image_loading.py

@@ -0,0 +1,132 @@
+"""
+Reproduce: VLM URL image loading with HF datasets.
+Tests cast_column(Image()) vs manual download approaches.
+Dataset: google-research-datasets/conceptual_captions (subset: labeled)
+"""
+from datasets import load_dataset, Image as datasets_Image, Dataset
+from PIL import Image as PILImage
+from io import BytesIO
+from itertools import islice
+import time
+
+DATASET = "google-research-datasets/conceptual_captions"
+SUBSET = "labeled"
+SPLIT = "train"
+N_SAMPLES = 20  # small slice for testing
+
+print("=" * 60)
+print("Loading dataset (streaming, first N samples)...")
+print("=" * 60)
+ds = load_dataset(DATASET, name=SUBSET, split=SPLIT, streaming=True)
+rows = list(islice(ds, N_SAMPLES))
+dataset = Dataset.from_list(rows)
+
+print(f"Loaded {len(dataset)} samples")
+print(f"Columns: {dataset.column_names}")
+print(f"First image_url: {dataset[0]['image_url'][:100]}...")
+print()
+
+# ─── Test 1: cast_column(Image()) — what we tried ───
+print("=" * 60)
+print("TEST 1: cast_column(Image()) approach")
+print("=" * 60)
+try:
+    ds_cast = dataset.cast_column("image_url", datasets_Image())
+    success, fail = 0, 0
+    t0 = time.time()
+    for i, sample in enumerate(ds_cast):
+        try:
+            img = sample["image_url"]
+            if img is not None:
+                print(f"  [{i}] OK — {img.size} {img.mode}")
+                success += 1
+            else:
+                print(f"  [{i}] None returned")
+                fail += 1
+        except Exception as e:
+            print(f"  [{i}] FAILED: {type(e).__name__}: {str(e)[:80]}")
+            fail += 1
+    elapsed = time.time() - t0
+    print(f"\nResult: {success} ok, {fail} failed, {elapsed:.1f}s")
+except Exception as e:
+    print(f"CRASHED during iteration: {type(e).__name__}: {str(e)[:120]}")
+print()
+
+# ─── Test 2: Manual download with requests.Session ───
+print("=" * 60)
+print("TEST 2: requests.Session() approach")
+print("=" * 60)
+try:
+    import requests
+    session = requests.Session()
+    success, fail = 0, 0
+    t0 = time.time()
+    for i, sample in enumerate(dataset):
+        url = sample["image_url"]
+        try:
+            resp = session.get(url, timeout=10)
+            resp.raise_for_status()
+            img = PILImage.open(BytesIO(resp.content)).convert("RGB")
+            print(f"  [{i}] OK — {img.size} {img.mode}")
+            success += 1
+        except Exception as e:
+            print(f"  [{i}] FAILED: {type(e).__name__}: {str(e)[:80]}")
+            fail += 1
+    elapsed = time.time() - t0
+    print(f"\nResult: {success} ok, {fail} failed, {elapsed:.1f}s")
+except Exception as e:
+    print(f"CRASHED: {type(e).__name__}: {str(e)[:120]}")
+print()
+
+# ─── Test 3: urllib (stdlib) ───
+print("=" * 60)
+print("TEST 3: urllib approach (stdlib)")
+print("=" * 60)
+try:
+    from urllib.request import urlopen, Request
+    success, fail = 0, 0
+    t0 = time.time()
+    for i, sample in enumerate(dataset):
+        url = sample["image_url"]
+        try:
+            req = Request(url, headers={"User-Agent": "Mozilla/5.0"})
+            with urlopen(req, timeout=10) as resp:
+                img = PILImage.open(BytesIO(resp.read())).convert("RGB")
+            print(f"  [{i}] OK — {img.size} {img.mode}")
+            success += 1
+        except Exception as e:
+            print(f"  [{i}] FAILED: {type(e).__name__}: {str(e)[:80]}")
+            fail += 1
+    elapsed = time.time() - t0
+    print(f"\nResult: {success} ok, {fail} failed, {elapsed:.1f}s")
+except Exception as e:
+    print(f"CRASHED: {type(e).__name__}: {str(e)[:120]}")
+print()
+
+# ─── Test 4: fsspec directly with expand=True ───
+print("=" * 60)
+print("TEST 4: fsspec.open() with expand=True")
+print("=" * 60)
+try:
+    import fsspec
+    success, fail = 0, 0
+    t0 = time.time()
+    for i, sample in enumerate(dataset):
+        url = sample["image_url"]
+        try:
+            with fsspec.open(url, "rb", expand=True) as f:
+                img = PILImage.open(BytesIO(f.read())).convert("RGB")
+            print(f"  [{i}] OK — {img.size} {img.mode}")
+            success += 1
+        except Exception as e:
+            print(f"  [{i}] FAILED: {type(e).__name__}: {str(e)[:80]}")
+            fail += 1
+    elapsed = time.time() - t0
+    print(f"\nResult: {success} ok, {fail} failed, {elapsed:.1f}s")
+except Exception as e:
+    print(f"CRASHED: {type(e).__name__}: {str(e)[:120]}")
+
+print()
+print("=" * 60)
+print("DONE — compare success rates and timing above")
+print("=" * 60)