Merge develop branch into master (#3518)

* update ci-testing.yml (#3322)

* update ci-testing.yml

* update greetings.yml

* bring back os matrix

* update ci-testing.yml (#3322)

* update ci-testing.yml

* update greetings.yml

* bring back os matrix

* Enable direct `--weights URL` definition (#3373)

* Enable direct `--weights URL` definition

@KalenMike this PR will enable direct --weights URL definition. Example use case:
```
python train.py --weights https://storage.googleapis.com/bucket/dir/model.pt
```

* cleanup

* bug fixes

* weights = attempt_download(weights)

* Update experimental.py

* Update hubconf.py

* return bug fix

* comment mirror

* min_bytes

* Update tutorial.ipynb (#3368)

add Open in Kaggle badge

* `cv2.imread(img, -1)` for IMREAD_UNCHANGED (#3379)

* Update datasets.py

* comment

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* COCO evolution fix (#3388)

* COCO evolution fix

* cleanup

* update print

* print fix

* Create `is_pip()` function (#3391)

Returns `True` if file is part of pip package. Useful for contextual behavior modification.

```python
def is_pip():
    # Is file in a pip package?
    return 'site-packages' in Path(__file__).absolute().parts
```

* Revert "`cv2.imread(img, -1)` for IMREAD_UNCHANGED (#3379)" (#3395)

This reverts commit 21a9607e00.

* Update FLOPs description (#3422)

* Update README.md

* Changing FLOPS to FLOPs.

Co-authored-by: BuildTools <unconfigured@null.spigotmc.org>

* Parse URL authentication (#3424)

* Parse URL authentication

* urllib.parse.unquote()

* improved error handling

* improved error handling

* remove %3F

* update check_file()

* Add FLOPs title to table (#3453)

* Suppress jit trace warning + graph once (#3454)

* Suppress jit trace warning + graph once

Suppress harmless jit trace warning on TensorBoard add_graph call. Also fix multiple add_graph() calls bug, now only on batch 0.

* Update train.py

* Update MixUp augmentation `alpha=beta=32.0` (#3455)

Per VOC empirical results https://github.com/ultralytics/yolov5/issues/3380#issuecomment-853001307 by @developer0hye

* Add `timeout()` class (#3460)

* Add `timeout()` class

* rearrange order

* Faster HSV augmentation (#3462)

remove datatype conversion process that can be skipped

* Add `check_git_status()` 5 second timeout (#3464)

* Add check_git_status() 5 second timeout

This should prevent the SSH Git bug that we were discussing @KalenMike

* cleanup

* replace timeout with check_output built-in timeout

* Improved `check_requirements()` offline-handling (#3466)

Improve robustness of `check_requirements()` function to offline environments (do not attempt pip installs when offline).

* Add `output_names` argument for ONNX export with dynamic axes (#3456)

* Add output names & dynamic axes for onnx export

Add output_names and dynamic_axes names for all outputs in torch.onnx.export. The first four outputs of the model will have names output0, output1, output2, output3

* use first output only + cleanup

Co-authored-by: Samridha Shrestha <samridha.shrestha@g42.ai>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Revert FP16 `test.py` and `detect.py` inference to FP32 default (#3423)

* fixed inference bug ,while use half precision

* replace --use-half with --half

* replace space and PEP8 in detect.py

* PEP8 detect.py

* update --half help comment

* Update test.py

* revert space

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Add additional links/resources to stale.yml message (#3467)

* Update stale.yml

* cleanup

* Update stale.yml

* reformat

* Update stale.yml HUB URL (#3468)

* Stale `github.actor` bug fix (#3483)

* Explicit `model.eval()` call `if opt.train=False` (#3475)

* call model.eval() when opt.train is False

call model.eval() when opt.train is False

* single-line if statement

* cleanup

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* check_requirements() exclude `opencv-python` (#3495)

Fix for 3rd party or contrib versions of installed OpenCV as in https://github.com/ultralytics/yolov5/issues/3494.

* Earlier `assert` for cpu and half option (#3508)

* early assert for cpu and half option

early assert for cpu and half option

* Modified comment

Modified comment

* Update tutorial.ipynb (#3510)

* Reduce test.py results spacing (#3511)

* Update README.md (#3512)

* Update README.md

Minor modifications

* 850 width

* Update greetings.yml

revert greeting change as PRs will now merge to master.

Co-authored-by: Piotr Skalski <SkalskiP@users.noreply.github.com>
Co-authored-by: SkalskiP <piotr.skalski92@gmail.com>
Co-authored-by: Peretz Cohen <pizzaz93@users.noreply.github.com>
Co-authored-by: tudoulei <34886368+tudoulei@users.noreply.github.com>
Co-authored-by: chocosaj <chocosaj@users.noreply.github.com>
Co-authored-by: BuildTools <unconfigured@null.spigotmc.org>
Co-authored-by: Yonghye Kwon <developer.0hye@gmail.com>
Co-authored-by: Sam_S <SamSamhuns@users.noreply.github.com>
Co-authored-by: Samridha Shrestha <samridha.shrestha@g42.ai>
Co-authored-by: edificewang <609552430@qq.com>

utils/general.py

@@ -1,5 +1,6 @@
 # YOLOv5 general utils
 
+import contextlib
 import glob
 import logging
 import math
@@ -7,11 +8,13 @@ import os
 import platform
 import random
 import re
-import subprocess
+import signal
 import time
+import urllib
 from itertools import repeat
 from multiprocessing.pool import ThreadPool
 from pathlib import Path
+from subprocess import check_output
 
 import cv2
 import numpy as np
@@ -33,6 +36,26 @@ cv2.setNumThreads(0)  # prevent OpenCV from multithreading (incompatible with Py
 os.environ['NUMEXPR_MAX_THREADS'] = str(min(os.cpu_count(), 8))  # NumExpr max threads
 
 
+class timeout(contextlib.ContextDecorator):
+    # Usage: @timeout(seconds) decorator or 'with timeout(seconds):' context manager
+    def __init__(self, seconds, *, timeout_msg='', suppress_timeout_errors=True):
+        self.seconds = int(seconds)
+        self.timeout_message = timeout_msg
+        self.suppress = bool(suppress_timeout_errors)
+
+    def _timeout_handler(self, signum, frame):
+        raise TimeoutError(self.timeout_message)
+
+    def __enter__(self):
+        signal.signal(signal.SIGALRM, self._timeout_handler)  # Set handler for SIGALRM
+        signal.alarm(self.seconds)  # start countdown for SIGALRM to be raised
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        signal.alarm(0)  # Cancel SIGALRM if it's scheduled
+        if self.suppress and exc_type is TimeoutError:  # Suppress TimeoutError
+            return True
+
+
 def set_logging(rank=-1, verbose=True):
     logging.basicConfig(
         format="%(message)s",
@@ -53,12 +76,12 @@ def get_latest_run(search_dir='.'):
 
 
 def is_docker():
-    # Is environment a Docker container
+    # Is environment a Docker container?
     return Path('/workspace').exists()  # or Path('/.dockerenv').exists()
 
 
 def is_colab():
-    # Is environment a Google Colab instance
+    # Is environment a Google Colab instance?
     try:
         import google.colab
         return True
@@ -66,6 +89,11 @@ def is_colab():
         return False
 
 
+def is_pip():
+    # Is file in a pip package?
+    return 'site-packages' in Path(__file__).absolute().parts
+
+
 def emojis(str=''):
     # Return platform-dependent emoji-safe version of string
     return str.encode().decode('ascii', 'ignore') if platform.system() == 'Windows' else str
@@ -80,13 +108,13 @@ def check_online():
     # Check internet connectivity
     import socket
     try:
-        socket.create_connection(("1.1.1.1", 443), 5)  # check host accesability
+        socket.create_connection(("1.1.1.1", 443), 5)  # check host accessibility
         return True
     except OSError:
         return False
 
 
-def check_git_status():
+def check_git_status(err_msg=', for updates see https://github.com/ultralytics/yolov5'):
     # Recommend 'git pull' if code is out of date
     print(colorstr('github: '), end='')
     try:
@@ -95,9 +123,9 @@ def check_git_status():
         assert check_online(), 'skipping check (offline)'
 
         cmd = 'git fetch && git config --get remote.origin.url'
-        url = subprocess.check_output(cmd, shell=True).decode().strip().rstrip('.git')  # github repo url
-        branch = subprocess.check_output('git rev-parse --abbrev-ref HEAD', shell=True).decode().strip()  # checked out
-        n = int(subprocess.check_output(f'git rev-list {branch}..origin/master --count', shell=True))  # commits behind
+        url = check_output(cmd, shell=True, timeout=5).decode().strip().rstrip('.git')  # git fetch
+        branch = check_output('git rev-parse --abbrev-ref HEAD', shell=True).decode().strip()  # checked out
+        n = int(check_output(f'git rev-list {branch}..origin/master --count', shell=True))  # commits behind
         if n > 0:
             s = f"⚠️ WARNING: code is out of date by {n} commit{'s' * (n > 1)}. " \
                 f"Use 'git pull' to update or 'git clone {url}' to download latest."
@@ -105,7 +133,7 @@ def check_git_status():
             s = f'up to date with {url} ✅'
         print(emojis(s))  # emoji-safe
     except Exception as e:
-        print(e)
+        print(f'{e}{err_msg}')
 
 
 def check_python(minimum='3.7.0', required=True):
@@ -135,10 +163,11 @@ def check_requirements(requirements='requirements.txt', exclude=()):
         try:
             pkg.require(r)
         except Exception as e:  # DistributionNotFound or VersionConflict if requirements not met
-            n += 1
             print(f"{prefix} {r} not found and is required by YOLOv5, attempting auto-update...")
             try:
-                print(subprocess.check_output(f"pip install '{r}'", shell=True).decode())
+                assert check_online(), f"'pip install {r}' skipped (offline)"
+                print(check_output(f"pip install '{r}'", shell=True).decode())
+                n += 1
             except Exception as e:
                 print(f'{prefix} {e}')
 
@@ -178,7 +207,8 @@ def check_file(file):
     if Path(file).is_file() or file == '':  # exists
         return file
     elif file.startswith(('http://', 'https://')):  # download
-        url, file = file, Path(file).name
+        url, file = file, Path(urllib.parse.unquote(str(file))).name  # url, file (decode '%2F' to '/' etc.)
+        file = file.split('?')[0]  # parse authentication https://url.com/file.txt?auth...
         print(f'Downloading {url} to {file}...')
         torch.hub.download_url_to_file(url, file)
         assert Path(file).exists() and Path(file).stat().st_size > 0, f'File download failed: {url}'  # check