First torrent after booting does not start

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When starting a fresh Tribler instance, searching for a torrent and subsequently downloading it, the downloaded torrent does not start.

• This does not happen when starting a download using a .torrent file.
• This does not happen when allowing the metadata to be fully retrieved before starting the download.

Specifically, it keeps cycling through peers endlessly.

The workaround for this is to start and stop the torrent.

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Information from the debug screen:

For the stuck torrent. Libtorrent reports ses.num_upload_only_torrents equal to 1. After starting and stopping the torrent, the value is set to 0.

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I noticed a Timeout waiting for libtorrent DHT getting enough peers log message.

Commenting out these lines, fixes the issue:

TriblerExperimental/src/tribler/core/libtorrent/download_manager/download_manager.py

Lines 648 to 652 in b18fb19

	if self.dht_readiness_timeout > 0 and self.dht_ready_task is not None:
	try:
	await wait_for(shield(self.dht_ready_task), timeout=self.dht_readiness_timeout)
	except asyncio.TimeoutError:
	self._logger.warning("Timeout waiting for libtorrent DHT getting enough peers")

[qstokkink]

After some very extensive debugging (thanks @xoriole and @egbertbouman) I found the fix. Replace:

TriblerExperimental/src/tribler/core/libtorrent/download_manager/download_manager.py

Lines 636 to 637 in b18fb19

	_ = self.register_anonymous_task('AddTorrent', self._async_add_torrent, ltsession, infohash, atp,
	ignore=(Exception,))

with

_ = self.replace_task(f"AddTorrent{infohash}", self._async_add_torrent, ltsession, infohash, atp,
                                  ignore=(Exception,))