From: Sjors Provoost <sjors@sprovoost•nl>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Cc: Andreas Schildbach <google.com@schildbach•de>
Subject: Re: [bitcoindev] Does anyone still need testnet3?
Date: Fri, 14 Mar 2025 10:31:50 +0100 [thread overview]
Message-ID: <C899E966-6444-41EC-B977-96CFFCBF936A@sprovoost.nl> (raw)
In-Reply-To: <7c28f8e9-d221-4633-8b71-53b4db07fa78@schildbach.de>
Hi Andreas,
> By the way, testnet3 works great for us (for testing). I consider block storms a feature, because it tests our code in rough conditions. We had planned to support both testnets in the forseeable future.
>
> https://github.com/bitcoinj/bitcoinj/
The "good" news is that testnet4 has very frequent short reorgs. [0]
It appears that people are trying to CPU mine by exploiting the rule that difficulty drops to 1 after 20 minutes. For every real difficulty block that's mined, they instantly publish 5 or 6 blocks, right up against the rule that blocks can't be more than 2 hours in the future.
Another side-effect of that behavior is that on testnet4 MTP is typically in the future, rather than an hour in the past. Combined with the timewarp attack mitigation rule helped reveal some bugs. [1, 2, 3]
There is a potential counter measure [4] that involves re-orging out those low difficulty blocks, though it's just a hackathon proof-of-concept and not likely to be included in Bitcoin Core itself. If anyone were to run it, you'd get even more reorgs to test :-)
- Sjors
[0] https://fork.observer/?network=4
[1] https://github.com/benjamin-wilson/public-pool/commit/4282233d2f11ceecbd0d142e8292ccc9c37ea999
[2] https://github.com/stratum-mining/stratum/pull/1325
[3] https://github.com/bitcoin/bitcoin/pull/31600
[4] https://github.com/bitcoin/bitcoin/pull/31117
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prev parent reply other threads:[~2025-03-14 13:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-14 8:52 Sjors Provoost
2025-03-14 9:12 ` 'Andreas Schildbach' via Bitcoin Development Mailing List
2025-03-14 9:31 ` Sjors Provoost [this message]
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