About Windows threads that do not have "correct" names - those are the threads that did not run our code yet, or maybe never will.
When I just start the mysqld.exe, and set breakpoint in main(), there are already 2 threads created by default process threadpool, probably when loading shared libraries.

There is some discussion about it in https://stackoverflow.com/questions/34822072/why-does-windows-10-start-extra-threads-in-my-program

About "one_connection" as thread name - unlike in MySQL, thread names are synchronized with performance schema, so it is just the result of this.

wlad serg maybe later we can add a build-time option to add more details into a thread name, what'd you say?

Sometimes it's tricky to find a thread that executes your query. Okay in thread-per-connection mode it's fine, but in tpool you'll have to traverse all thread stacks to find one, if, say, you're just pausing the execution in gdb.

I solve this problem with parallel stacks in clion, it looks like this:

Yet I would definitely love to rely on such mouse-addicted interface less.

I solve this problem with Visual Studio, and others solve this problem with "SHOW PROCESSLIST", if they need an id. the os thread id is also there. Is thread-per-connection much better? How do you find your thread with 100 of threads?

@nikita, I would say, changing thread name twice per query (as in threadpool, to indicate thread ID, and to indicate "idle/waiting" state without THD) would be too expensive for optimized binary. For debug, it probably does not make any difference, so personally I would not care (but I did not care about thread names being perfschema-compatible in the first place, just did it on @serg's request)