From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Sat, 25 Jul 2026 11:30:09 -0700 Received: from mail-oa1-f56.google.com ([209.85.160.56]) by mail.fairlystable.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1wnh8T-0006cf-1I for bitcoindev@gnusha.org; Sat, 25 Jul 2026 11:30:09 -0700 Received: by mail-oa1-f56.google.com with SMTP id 586e51a60fabf-4519fdc5145sf1497027fac.1 for ; Sat, 25 Jul 2026 11:30:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlegroups.com; s=20251104; t=1785004202; x=1785609002; darn=gnusha.org; h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post :list-id:mailing-list:precedence:x-original-sender:content-type :mime-version:subject:references:in-reply-to:message-id:to:from:date :sender:from:to:cc:subject:date:message-id:reply-to:content-type; bh=SKkRaaFsFZWZ0a2xZOJWfQWpQvpJ8ENu9xkUU+FZaCE=; b=hLLGjjaCOepfGnTHSK5a8o6lzXj2NE4entBtZT+qwCFtt1POnYtpxxblMKHW2nl/pQ By/r5wD2jS3KhrQi0HV/VGC59j9owd/a01TZ+OKU+//DmbkEEww/y485iAIbnYrbS26t BqgC4GxxbKznRF/oJl2LU3N8+amMTYn1fDgiNt01VDxwTtqLPV3vVf48cxPxsfP+V1+/ R/jvQZ4hrLadvl6wXCUJelDBTO1Jzr+G09arUYs7DEjRNffF3X/PFWC88mnzxeyBqpVy wMY/o9p2wmntjBQQ1h9exshoaEa0P4I6/IMplUWg+LIv8a3M+0TxbODmQDejgyZX6t2n dKNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785004202; x=1785609002; h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post :list-id:mailing-list:precedence:x-original-sender:content-type :mime-version:subject:references:in-reply-to:message-id:to:from:date :x-beenthere:x-gm-message-state:sender:from:to:cc:subject:date :message-id:reply-to:content-type; bh=SKkRaaFsFZWZ0a2xZOJWfQWpQvpJ8ENu9xkUU+FZaCE=; b=L7Rbyn2Jpu2jrpxcauxWYVblSiFCRU8iK3K1F8DnKRVj2+kVMfZQ14RPurpk41RieK HTK6RXHrjblb/Vz6kMpSCfC03le4QCvT5x95d6EjzwViJwExc9YCpqiUf6ebVfAdZlNd waTPjPy1Q0jM27wy806P73+xXXA1PPaY2h0QX+J9e14QlasU3Acp3mJ9BW4yhpiyo8zY aqZ0sqbRLdtTWLYVWdSviJvRISTGIReYKkrW/F1iNPGpQFmJ0MzoTUhlyx6OzTw21/3X fbuJmTMuNyM666iCEiF4cOkssRL0acKRRt1L5kHQGCdNGFSNm3GjxPenDLxyYCRIO9Dg 6KLA== Sender: bitcoindev@googlegroups.com X-Forwarded-Encrypted: i=1; AHgh+RpdFvaECDyQYN7hNsSN/YQ1bZinMbmHqJbwZGuJz+h0yM7JBcU46vM/aeLL9WP2r73O9g/1Z0cE2Pgg@gnusha.org X-Gm-Message-State: AOJu0YxjrwUIjF1h7jnrBjgTug6O028Y6mFjG0i/ftJ6Fkegc81U/Mpy jhQhX74QfRxARrljSkhsj1+LdjekZtcy4Yx4z+D7CP6vn/jjDNCRaD28 X-Received: by 2002:a05:6808:d4b:b0:495:9870:2b25 with SMTP id 5614622812f47-4ab6a1fe862mr2857696b6e.34.1785004202512; Sat, 25 Jul 2026 11:30:02 -0700 (PDT) X-BeenThere: bitcoindev@googlegroups.com; h="Aa7YSPSbu/JdkHm9FmndbXH9Kmf5K8bmF9KN/OS4UcHlaQ6v2A==" Received: by 2002:a05:6870:1408:b0:456:7cc0:8618 with SMTP id 586e51a60fabf-4579da2b047ls1517077fac.1.-pod-prod-06-us; Sat, 25 Jul 2026 11:29:56 -0700 (PDT) X-Received: by 2002:a05:6808:244e:b0:479:f7e7:4a81 with SMTP id 5614622812f47-4ab69c50a57mr2718320b6e.0.1785004196341; Sat, 25 Jul 2026 11:29:56 -0700 (PDT) Received: by 2002:a05:690c:26c8:b0:81e:11b4:1172 with SMTP id 00721157ae682-81f5a8b0fdams7b3; Sat, 25 Jul 2026 11:23:03 -0700 (PDT) X-Received: by 2002:a05:690c:4b11:b0:809:9422:8c47 with SMTP id 00721157ae682-81f69d35d44mr10545607b3.22.1785003782742; Sat, 25 Jul 2026 11:23:02 -0700 (PDT) Date: Sat, 25 Jul 2026 11:23:02 -0700 (PDT) From: Ali Sherief To: Bitcoin Development Mailing List Message-Id: <3d57026c-7998-468b-ab72-b57cc2e971f2n@googlegroups.com> In-Reply-To: References: Subject: [bitcoindev] Re: Testnet 4 difficulty/hashrate MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_175214_1737207568.1785003782151" X-Original-Sender: ali@notatether.com Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.7 (/) ------=_Part_175214_1737207568.1785003782151 Content-Type: multipart/alternative; boundary="----=_Part_175215_417983591.1785003782151" ------=_Part_175215_417983591.1785003782151 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable This is having consequences in development workflows. Tests with=20 bitcoin-related libraries with this kind of block generation is now almost= =20 impossible unless you mine your old blocks. For instance, my testnet4=20 faucet transactions have been sitting in the almost-empty mempool for=20 around 30-60 minutes, never confirm, and then drop out. It is certainly making developing Bitcoin-related stuff much harder -Ali On Friday, June 5, 2026 at 1:28:01=E2=80=AFPM UTC+3 Anthony Towns wrote: > On Fri, Jun 05, 2026 at 07:35:27PM +1000, Anthony Towns wrote: > > compared with current mainnet difficulty of ~138T, or testnet4's=20 > > current difficulty of ~1239M, > > If testnet4's current difficulty is D=3D1239M [0], and there were > no min-difficulty blocks, that would be one thing. But there are > min-difficulty blocks, and sufficient hashrate mining them with the clock > set forward to saturate them. What's the actual hashrate for testnet4 > given a reported difficulty D? > > [0]=20 > https://mempool.space/testnet4/block/000000000000000359f805aea2a5f18671bf= 98a1106d0cdbbfbe1f341f5e08dc?showDetails=3Dtrue&view=3Dactual#details > > Suppose the "correct" difficulty corresponding with actual hashrate would > be H. Then real difficulty blocks are found every (D/H * 10 minutes) > on average, and minimum time blocks fill up the rest of the retarget > period. So between blocks 135072 and 137087, I see 192 real-difficulty > blocks and 1824 min-difficulty blocks, suggesting that the real testnet4 > difficulty should be H=3D130M. > > The limit on not having D/H=3D2016 is that with 2016 min-difficulty block= s, > you'd have a retarget period taking up 4 weeks instead of 2 weeks. I thin= k > a real-difficulty block can reset up to 5 or 6 blocks of min-difficulty > time (any more than that would violate median time constraints on behalf > of the real difficulty block, or too-far-in-future constraints on the > min-difficulty blocks), so I think that means that you want at least > 1 real block for every 10 or 12 min-difficulty blocks, so a 192:1824 > (1:9.5) ratio seems close to the max already. > > This also suggests ~90% of testnet4 blocks are being confirmed via > competition in network propagation with only ~10% confirmed via > PoW/hashrate competition. > > Cheers, > aj > > --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+unsubscribe@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/= 3d57026c-7998-468b-ab72-b57cc2e971f2n%40googlegroups.com. ------=_Part_175215_417983591.1785003782151 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable This is having consequences in development workflows. Tests with bitcoin-re= lated libraries with this kind of block generation is now almost impossible= unless you mine your old blocks. For instance, my testnet4 faucet transact= ions have been sitting in the almost-empty mempool for around 30-60 minutes= , never confirm, and then drop out.

It is certainly ma= king developing Bitcoin-related stuff much harder

-Ali

On Friday, June 5, 2026 at 1:28:01=E2=80=AFPM UTC+3 Anthony= Towns wrote:
On Fri, Jun 05, 2026 at 07:35:27PM +1000, Anthony Towns wrote:
> compared with current mainnet difficulty of ~138T, or testnet4'= ;s=20
> current difficulty of ~1239M,

If testnet4's current difficulty is D=3D1239M [0], and there were
no min-difficulty blocks, that would be one thing. But there are
min-difficulty blocks, and sufficient hashrate mining them with the clo= ck
set forward to saturate them. What's the actual hashrate for testne= t4
given a reported difficulty D?

[0] https://mempool.spac= e/testnet4/block/000000000000000359f805aea2a5f18671bf98a1106d0cdbbfbe1f341f= 5e08dc?showDetails=3Dtrue&view=3Dactual#details

Suppose the "correct" difficulty corresponding with actual ha= shrate would
be H. Then real difficulty blocks are found every (D/H * 10 minutes)
on average, and minimum time blocks fill up the rest of the retarget
period. So between blocks 135072 and 137087, I see 192 real-difficulty
blocks and 1824 min-difficulty blocks, suggesting that the real testnet= 4
difficulty should be H=3D130M.

The limit on not having D/H=3D2016 is that with 2016 min-difficulty blo= cks,
you'd have a retarget period taking up 4 weeks instead of 2 weeks. = I think
a real-difficulty block can reset up to 5 or 6 blocks of min-difficulty
time (any more than that would violate median time constraints on behal= f
of the real difficulty block, or too-far-in-future constraints on the
min-difficulty blocks), so I think that means that you want at least
1 real block for every 10 or 12 min-difficulty blocks, so a 192:1824
(1:9.5) ratio seems close to the max already.

This also suggests ~90% of testnet4 blocks are being confirmed via
competition in network propagation with only ~10% confirmed via
PoW/hashrate competition.

Cheers,
aj

--
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