Bitcoin Forum

Hello,

I would like to point out a problem that i have for at least few years on bitcoin core qt since version 0.8 to 0.12. not sure if bitcoind has the same issue.

The problem happens in most of time when bitcoin qt synchronizing with network, it will first start downloading at full speed (about 5MB per second with 8 connections). soon later it will stop downloading while the network is always in prefect condition. i thought it's cache might reach the limit(which i set to 3GB) and that could be the reason why it stopped downloading just to verify blocks.

But then i checked the cpu rate in use, it was under 10% !!! 0 byte downloading, cpu use rate under 10%. current blocks verified slowly increase about 5 secs per block, that's not the libsecp256k1 performance !!! this situation can continue for a very long time >30 minutes then suddenly everything returns normal, download back to 5MB per second and cpu back to over 50% and 1 sec per block verified.

So the question is why is this happening? does bitcoin qt stop downloading while it has enough blocks to verify say every 1GB downloaded? What can i do when it strikes and do nothing? some one please check the the source code of related parts.

spec:

I7 6700K + M2 PCIE 3.0*4 SSD + 64GB ram + 50mb per second network
I need it to download at 100% bandwidth and verify blocks with 100% CPU usage at the same time

Does this happen if you use 0.13.0+?

I guess so since there is no code changes about the verify and download functions in 0.13. can't find anyone pointed out this issue neither.

But you haven't tried, and that is completely unhelpful. I need you to try and see if you run into the same problems. Just because the code hasn't changed specifically there does not mean that the problem still exists as code changes elsewhere can also effect what happens.