Bitcoin Core rescanning use only 1 CPU Core

[Kulahin]

When i run bitcoin-qt.exe with -zapwallettxes parameter, it rescan my wallet, but using only 1 of 20 core ~6.6% of maximum, and only 60-90 MB/sec reading on M2SSD drive. How can i add more cores for running QT ?

https://i.imgur.com/zNQMgJ3.png
^{bitcoin.conf = dbcache = 20000 par = 15 txindex = 1 addresstype = legacy proxy=127.0.0.1:9050 listen=1 bind=127.0.0.1 onlynet=onion datadir=E:\Roaming\Bitcoin blocksdir=E:\Roaming\Bitcoin}

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[DaveF]

As far as I know and have seen it's locked to one core. Some people have hacked together ways around it but you would have to dig. I had a similar issue a year or so ago and in the end just said screw it and let it run for hours till it finished.

Others might be able to give you better advice, but I would just let it run. If you stop it and start again with other parameters and they don't work you just lost all the time it was running now.

-Dave

[khaled0111]

...

If he finds a way to make bitcoin-qt uses more cores, will this really speed up the rescanning process? I doubt it will!
Setting the dbcache value properly and using an ssd would be enough.
From the configuration shared in OP, the dbcache is set to 20000 which is way too much, in my opinion.

[nc50lc]

From the configuration shared in OP, the dbcache is set to 20000 which is way too much, in my opinion.

If he has 32GB of RAM and more, there's no harm on using a high cache size.
The problem in the config is par=15 which limits his system on using 15cores while the default "0" will use all available cores if needed.

For the issue, OP might had just started the -reindex when he posted this thread.
At which point that there're no signature validation required for earlier blocks thus wont require a lot of CPU usage.
If not, there must be a bottleneck somewhere.

[Kulahin]

PC has 128gb ram
i try to change -par and -dbcache parameters, nothing changes, bitcoin-qt always use 1 of 20 core.