`bitcoind` RPC: ask if syncing headers or blocks

Question

Is there a way to know from bitcoind RPC if it's syncing headers or blocks? And is there a way to know the header sync progress?

Even if not directly available, is it possible to derive header sync progress from other information through RPC?

I tried to get this information from the debug log, but the problem there is that occasionally, the last header sync log message looks like this

Synchronizing blockheaders, height: 1660930 (~95.02%)

It never logs out whether it reached 100% or not, and that's a problem for the software that I'm working on.

Pieter Wuille · Accepted Answer · 2020-01-14 23:31:20Z

2

The getblockchaininfo RPC will tell you have many blocks and headers you have. When the number of headers is larger, you're still synchronizing.

answered Jan 14, 2020 at 23:31

Pieter Wuille

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I'm not asking about whether bitcoind is syncing blocks or not. I'm talking about the header-first sync. I want to know the progress of that.
– M.K. Safi
Jan 14, 2020 at 23:40
1

Oh, I misread. In that case the answer is even easier: you can't know.
– Pieter Wuille
Jan 15, 2020 at 0:27
Pieter, what about comparing startingheight from the getpeerinfo response with the header field from the getblockchaininfo response?
– M.K. Safi
Jan 28, 2020 at 18:44
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If an approximate answer is enough, you can just look at the timestamp of the last header. That's more accurate than relying on startingheight (which will be outdated for long lived connections).
– Pieter Wuille
Jan 28, 2020 at 19:20
1

The point I'm trying to make is that there is no exact answer to this question: your node is always syncing headers, and is never "done". There may be a block that was just mined, but you haven't learned about, so you can never be sure you're caught up.
– Pieter Wuille
Jan 28, 2020 at 19:22

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