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Code Issues Projects Releases Wiki Activity

Native concurrent downloading of fragments (#166)

Browse Source 
* Option `--concurrent-fragments` (`-N`) to set the number of threads

Related: #165

Known issues:
* When receiving Ctrl+C, the process will exit only after finishing the currently downloading fragments
* The download progress shows the speed of only one thread

Authored by shirt-dev
This commit is contained in:
shirt
2021-03-12 23:46:58 -05:00
committed by GitHub
parent 0a473f2f0f
commit 4cf1e5d2f9
7 changed files with 250 additions and 104 deletions
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152
yt_dlp/downloader/dash.py
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@ -1,11 +1,18 @@
from __future__ import unicode_literals
try:
import concurrent.futures
can_threaded_download = True
except ImportError:
can_threaded_download = False
from ..downloader import _get_real_downloader
from .fragment import FragmentFD
from ..compat import compat_urllib_error
from ..utils import (
DownloadError,
sanitize_open,
urljoin,
)
@ -49,47 +56,11 @@ class DashSegmentsFD(FragmentFD):
assert fragment_base_url
fragment_url = urljoin(fragment_base_url, fragment['path'])
if real_downloader:
fragments_to_download.append({
'url': fragment_url,
})
continue
# In DASH, the first segment contains necessary headers to
# generate a valid MP4 file, so always abort for the first segment
fatal = i == 0 or not skip_unavailable_fragments
count = 0
while count <= fragment_retries:
try:
success, frag_content = self._download_fragment(ctx, fragment_url, info_dict)
if not success:
return False
self._append_fragment(ctx, frag_content)
break
except compat_urllib_error.HTTPError as err:
# YouTube may often return 404 HTTP error for a fragment causing the
# whole download to fail. However if the same fragment is immediately
# retried with the same request data this usually succeeds (1-2 attempts
# is usually enough) thus allowing to download the whole file successfully.
# To be future-proof we will retry all fragments that fail with any
# HTTP error.
count += 1
if count <= fragment_retries:
self.report_retry_fragment(err, frag_index, count, fragment_retries)
except DownloadError:
# Don't retry fragment if error occurred during HTTP downloading
# itself since it has own retry settings
if not fatal:
self.report_skip_fragment(frag_index)
break
raise
if count > fragment_retries:
if not fatal:
self.report_skip_fragment(frag_index)
continue
self.report_error('giving up after %s fragment retries' % fragment_retries)
return False
fragments_to_download.append({
'frag_index': frag_index,
'index': i,
'url': fragment_url,
})
if real_downloader:
info_copy = info_dict.copy()
@ -102,5 +73,104 @@ class DashSegmentsFD(FragmentFD):
if not success:
return False
else:
def download_fragment(fragment):
i = fragment['index']
frag_index = fragment['frag_index']
fragment_url = fragment['url']
ctx['fragment_index'] = frag_index
# In DASH, the first segment contains necessary headers to
# generate a valid MP4 file, so always abort for the first segment
fatal = i == 0 or not skip_unavailable_fragments
count = 0
while count <= fragment_retries:
try:
success, frag_content = self._download_fragment(ctx, fragment_url, info_dict)
if not success:
return False, frag_index
break
except compat_urllib_error.HTTPError as err:
# YouTube may often return 404 HTTP error for a fragment causing the
# whole download to fail. However if the same fragment is immediately
# retried with the same request data this usually succeeds (1-2 attempts
# is usually enough) thus allowing to download the whole file successfully.
# To be future-proof we will retry all fragments that fail with any
# HTTP error.
count += 1
if count <= fragment_retries:
self.report_retry_fragment(err, frag_index, count, fragment_retries)
except DownloadError:
# Don't retry fragment if error occurred during HTTP downloading
# itself since it has own retry settings
if not fatal:
break
raise
if count > fragment_retries:
if not fatal:
return False, frag_index
self.report_error('giving up after %s fragment retries' % fragment_retries)
return False, frag_index
return frag_content, frag_index
def append_fragment(frag_content, frag_index):
if frag_content:
fragment_filename = '%s-Frag%d' % (ctx['tmpfilename'], frag_index)
try:
file, frag_sanitized = sanitize_open(fragment_filename, 'rb')
ctx['fragment_filename_sanitized'] = frag_sanitized
file.close()
self._append_fragment(ctx, frag_content)
return True
except FileNotFoundError:
if skip_unavailable_fragments:
self.report_skip_fragment(frag_index)
return True
else:
self.report_error(
'fragment %s not found, unable to continue' % frag_index)
return False
else:
if skip_unavailable_fragments:
self.report_skip_fragment(frag_index)
return True
else:
self.report_error(
'fragment %s not found, unable to continue' % frag_index)
return False
max_workers = self.params.get('concurrent_fragment_downloads', 1)
if can_threaded_download and max_workers > 1:
self.report_warning('The download speed shown is only of one thread. This is a known issue')
with concurrent.futures.ThreadPoolExecutor(max_workers) as pool:
futures = [pool.submit(download_fragment, fragment) for fragment in fragments_to_download]
# timeout must be 0 to return instantly
done, not_done = concurrent.futures.wait(futures, timeout=0)
try:
while not_done:
# Check every 1 second for KeyboardInterrupt
freshly_done, not_done = concurrent.futures.wait(not_done, timeout=1)
done |= freshly_done
except KeyboardInterrupt:
for future in not_done:
future.cancel()
# timeout must be none to cancel
concurrent.futures.wait(not_done, timeout=None)
raise KeyboardInterrupt
results = [future.result() for future in futures]
for frag_content, frag_index in results:
result = append_fragment(frag_content, frag_index)
if not result:
return False
else:
for fragment in fragments_to_download:
frag_content, frag_index = download_fragment(fragment)
result = append_fragment(frag_content, frag_index)
if not result:
return False
self._finish_frag_download(ctx)
return True