Prevent all threads from using the same POW nonce.

[penguins-cymbals]

GolosChain#37

Not sure how to issue the pull request cross-chains, but anyways, the same thing applies to steemit.

The nonce should be different for each thread, otherwise all threads are performing the exact same hash, which means effectively on a machine with N cores you were only actually performing 1 core's worth of work.
This should hopefully bring back some fairness in mining.

Since I'm giving up my unfair advantage, I hope this comes with a bug bounty from steemit and/or golos. Please PM 'penguin' in golos or steemit chat if so, so I can say where to issue it. :)

[abitmore]

Threads aren't using same nounces, see this line of code: https://github.com/steemit/steem/blob/v0.14.2/libraries/plugins/witness/witness.cpp#L491 .
Simply, hash rate should be higher if mining-threads in config.ini set to more than 1 and if the machine has more than 1 core.

//Edit: my bad.. just checked the PR. Stupid bug.

[penguins-cymbals]

thread_num is never changed in the current code base, it is always 0.

[abitmore]

You're right. It's introduced in this commit: 42e95ba#diff-76b4b57a464fcf6ec0c0525753ed1222L587

[arhag]

@abitmore: Actually the bug was first introduced with this commit: 581317f#diff-76b4b57a464fcf6ec0c0525753ed1222

[theoreticalbts]

Fixed, merged.