Opening Debug Pane freezes Tribler Core and uses 100% of disk for a while

[xoriole]

Describe the bug
Opening the Debug Pane on Windows freezes the Tribler Core and uses 100% of disk for a while.

Here is a screenshot:

Environment:

• OS: Windows 10
• Tribler's version 7.13.0

Additional context
It is the core that is frozen. The GUI is still responsive. After a while, the disk usage reduces and the Debug Pane is populated with data.

[drew2a]

It appears that I can't reproduce the bug. When I'm not subscribed to any channels, I don't observe any CPU spikes while opening the 'Debug panel.' However, if I am subscribed to a channel, my CPU usage consistently remains at 100%.

OS: macOS.

[xoriole]

One of the reasons for Core freezing is the call to /statistics/tribler endpoint which takes a long time to respond. Here is an HTTP request log using httpie library.

tribler/src/tribler/core/components/restapi/rest/statistics_endpoint.py

Lines 51 to 59 in e8b8354

	async def get_tribler_stats(self, request):
	stats_dict = {}
	if self.mds:
	db_size = self.mds.get_db_file_size()
	stats_dict = {"db_size": db_size,
	"num_channels": self.mds.get_num_channels(),
	"num_torrents": self.mds.get_num_torrents()}
	return RESTResponse({'tribler_statistics': stats_dict})

Mocking the response to the statistics endpoint makes Trible responsive again. So, a solution would be to make this endpoint more efficient by making the underlying queries more performant.

Since channels are removed in the big giga cleanup, I don't think it is worth trying to solve this issue separately. Therefore, I'll close this issue.

[xoriole]

Re-opening this issue, the original problem persists.
The issue is the count query like the following:

	select count(1) from ChannelNode whre metadata_type==300

[qstokkink]

My metadata.db only has a measly 12402 entries, nowhere near the 5 million reported in OP. Any help* with this would be appreciated.

*If someone wants to share their huge metadata.db file with me, that would be great. Or, alternatively, solve this issue.