From 7b6cdd9fc31ecf3e7ad7ae0cfa211507134d605b Mon Sep 17 00:00:00 2001
From: "codeflash-ai[bot]"
 <148906541+codeflash-ai[bot]@users.noreply.github.com>
Date: Wed, 12 Nov 2025 02:50:52 +0000
Subject: [PATCH] Optimize MnliProcessor._create_examples

The optimized code achieves a **20% speedup** through three key optimizations that eliminate redundant operations in the main loop:

**What was optimized:**

1. **Early exit for empty datasets**: Added `if len(lines) <= 1: return []` to avoid unnecessary loop setup when there are no data rows beyond the header.

2. **Pre-computed test condition**: Moved `set_type.startswith("test")` outside the loop into `is_test = set_type.startswith("test")`, eliminating 6,420 repeated string method calls per execution.

3. **Direct slice iteration**: Replaced `enumerate(lines)` with `for line in lines[1:]` to skip the header directly, eliminating the need for an index variable and the `if i == 0: continue` check on every iteration.

**Why this leads to speedup:**

The line profiler shows the original code spent significant time on the `set_type.startswith("test")` check (13.1% of total time) and the `enumerate` overhead (9.2% of total time). By pre-computing the test condition and using direct slicing, these operations are eliminated from the hot loop. The optimizations are particularly effective for larger datasets, as shown in the test results where improvements range from 19-22% for 500-1000 examples.

**Performance characteristics:**
- Small datasets (single examples): 2-12% improvement
- Medium datasets (100-300 examples): 16-20% improvement
- Large datasets (500-1000 examples): 19-22% improvement
- Edge cases (empty datasets): Up to 67% improvement due to early exit

The optimizations preserve all behavior including error handling for malformed data and maintain the same output format and exception conditions.
---
 src/transformers/data/processors/glue.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/transformers/data/processors/glue.py b/src/transformers/data/processors/glue.py
index abf03c917202..7e15cb8db421 100644
--- a/src/transformers/data/processors/glue.py
+++ b/src/transformers/data/processors/glue.py
@@ -204,14 +204,16 @@ def get_labels(self):
 
     def _create_examples(self, lines, set_type):
         """Creates examples for the training, dev and test sets."""
+        if len(lines) <= 1:
+            return []
+
+        is_test = set_type.startswith("test")
         examples = []
-        for i, line in enumerate(lines):
-            if i == 0:
-                continue
+        for line in lines[1:]:
             guid = f"{set_type}-{line[0]}"
             text_a = line[8]
             text_b = line[9]
-            label = None if set_type.startswith("test") else line[-1]
+            label = None if is_test else line[-1]
             examples.append(InputExample(guid=guid, text_a=text_a, text_b=text_b, label=label))
         return examples