log, doc: Confusing log message #17139

bitcoind -par=1

Excerpt from the debug.log:

Using 0 threads for script verification

Zero? I guess not ;)

It's always been like that. It doesn't count the main thread in that message. "Threads" counts the extra threads. Feel free to change it to:

Using 0 additional threads for script verification

"Threads" counts the extra threads.

But setting -par=2 gets "Using 2 threads for script verification".

Huh.

EDIT: Corrected number of dedicated script-checking threads (thanks @sipa)

Here's the help message:

  -par=<n>
       Set the number of script verification threads (-4 to 16, 0 = auto, <0 =
       leave that many cores free, default: 0)

The behavior is confusing here:

• not having a par setting, setting -par=0 or setting -nopar: defaults to starting GetNumCores() - 1 dedicated script-checking threads
• setting -par=1: starts no dedicated script-checking threads and does all script-checking on the main thread. This is confusing and undocumented!
• setting -par=n for n > 1: starts n - 1 dedicated script-checking threads (up to a max of 16)
• setting -par=-n for n > 1: starts GetNumCores() - n dedicated script-checking threads. This is weird but at least it's documented!

No, -par=N should start N-1 script checking threads, as the main thread always participates (so there should always be N threads in total doing script verification, for N>=1).