release note: cpfp carveout removed in 31.0 #34266

1. 
   instagibbs commented at 8:56 PM on January 12, 2026: member

   Seems it was overlooked for release notes, so let's add something

2. 
   DrahtBot commented at 8:56 PM on January 12, 2026: contributor

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   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/34266.

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   LLM Linter (✨ experimental)

   Possible typos and grammar issues:

   • 10kvB -> 10 kB [“10kvB” is not a valid/recognizable size unit; separate the number and unit (e.g., “10 kB”) so the size is comprehensible]

   ^2026-01-12

3. instagibbs force-pushed on Jan 12, 2026
4. DrahtBot added the label CI failed on Jan 12, 2026
5. in doc/release-notes-33629.md:50 in 1d4a7c023d

     45 | +- The "CPFP Carveout" has been removed from the mempool logic. The CPFP carveout
     46 | +  allowed one additional child transaction to be added to a package that's already
     47 | +  at its descendant limit, but only if that child has exactly one ancestor
     48 | +  (the package's root) and is small (no larger than 10kvB). The addition of a cluster count
     49 | +  limit makes the CPFP carveout rule useless, because a carveout
     50 | +  cannot be allowed to bypass the cluster count limit. It is expected that smart
   

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   l0rinc commented at 10:22 PM on January 12, 2026:

   I might be off here, but is it cluster count or size limit?

   https://github.com/bitcoin/bitcoin/blob/34a77138b7a6f65a31c6273f2770e943cc0b474b/src/txgraph.cpp#L1957-L1960 and https://github.com/bitcoin/bitcoin/blob/34a77138b7a6f65a31c6273f2770e943cc0b474b/src/txgraph.cpp#L2134 indicates it's size:

     (the package's root) and is small (no larger than 10kvB). The addition of a cluster size
     limit makes the CPFP carveout rule useless, because a carveout
     cannot be allowed to bypass the cluster size limit. It is expected that smart
   

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   sipa commented at 10:29 PM on January 12, 2026:

   It's count.

   The old ancestor count limit was 25. The CPFP carve-out allowed ancestor sets in specific circumstances to have 26 elements.

   There is no more ancestor count limit, instead there is a cluster count limit of 64, which has no exceptions.

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   l0rinc commented at 10:30 PM on January 12, 2026:

   thanks for clarifying, please resolve

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   instagibbs commented at 10:31 PM on January 12, 2026:

   interestingly the commit language I was cribbing a bit from said size, but yes it's actually count

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   glozow commented at 10:59 PM on January 12, 2026:

     (the package's root) and is small (no larger than 10kvB). 
     Nothing is allowed to bypass the cluster count limit. It is expected that smart
   

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   instagibbs commented at 11:04 PM on January 12, 2026:

   done

6. l0rinc approved
7. DrahtBot removed the label CI failed on Jan 12, 2026
8. release note: cpfp carveout removed in 31.0 61726483e1
9. instagibbs force-pushed on Jan 12, 2026
10. 
    l0rinc commented at 11:06 PM on January 12, 2026: contributor

    ACK 61726483e1c226c87212d0e12a3dd640fc393791

11. 
    glozow commented at 11:10 PM on January 12, 2026: member

    ACK 61726483e1c226c87212d0e12a3dd640fc393791

12. glozow merged this on Jan 12, 2026
13. glozow closed this on Jan 12, 2026

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14. fanquake added the label Docs on Jan 13, 2026
15. fanquake added this to the milestone 31.0 on Jan 13, 2026

Contributors

instagibbsDrahtBotl0rincsipaglozow

Milestone
31.0