Forward profile events to client

[novikd]

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Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):
Send profile events from server to client. New packet type ProfileEvents was introduced. Closes #26177.

[novikd]

@Mergifyio update

[mergify]

Command update: success

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All committers have signed the CLA.

[nikitamikhaylov]

What will I see in case of distributed queries?

[alexey-milovidov]

@nikitamikhaylov Events for distributed queries are just forwarded (not merged anyhow) so the events from different servers can be distinguished on the client to show various summaries like: maximum memory usage across all servers, total memory usage summed across all servers, multiple individual progress bars, etc...

[alexey-milovidov]

This is how it's supposed to work, I did not read the PR though :)

[novikd]

All profile events are supposed to be forwarded to the client (You can see that in RemoteQueryExecutor). The client handles all the data. After this change it will compute number of threads, cores and memory used on all the hosts.

[nikitamikhaylov]

snapshots.reserve() after we acquire a lock?

[azat]

@novikd Maybe ProfileEvents packets should be sent only if they were requested, like send_logs_level (and enable it automatically on client if some options was enabled)?
This will also fix #30134

P.S. I've also verified that it does not decrease throughput of a simple select 1 query (i.e. clickhouse-benchmark --query 'select 1' -i10000)

[alexey-milovidov]

@azat Better to avoid complications.
I see it can be needed only for tests.

[alexey-milovidov]

@nikitamikhaylov The whole implementation is wrong.

increment values should send increments, not accumulated values.