Hello ๐ folks, Iโm Kevkevin. Iโm an open-source developer and reporter for Insider Edition. Last week I reviewed several pull requests from the Bitcoin Core repo. One merge this week changes the compact-block reconstruction log. When a peer prefills a transaction this node already has, in the mempool or in the extrapool, that prefill is now its own count and its own byte size. The old line folded the extrapool into the mempool number. The new one reports prefill, mempool, extrapool, and the transactions that still had to be requested as four separate numbers.
Another merge removes -persistmempoolv1. That option wrote mempool.dat in the legacy format so a node could downgrade to v26 or earlier. Those releases are unsupported. The file is always written in the current format, with a random XOR key. A v1 file still loads.
Thursdayโs #bitcoin-core-dev meeting was not held. stickies-v left a reminder that many people could not attend. Later, eugenesiegel asked about startup failures after power loss, and nkaretnikov pointed at the missing-undo report and the chainstate rewrite discussion. v32.0rc4 is tagged, and the binaries are up. Final v32.0 is not.
Merged PRโs
Every week, several changes are officially added to Bitcoin Core. This week, 22 changes were merged. Here are some I found interesting this week.
cmpctblock: Improve logging of
cmpctblockmessage reconstruction statistics [part of prefill series] by David Gumberg
The compact-block reconstruction log used to fold extrapool hits into the mempool number. On a successful FillBlock it now prints four separate counts with byte sizes: prefilled, from mempool, from extrapool, and requested. A second debug line reports redundant prefills, meaning prefilled transactions the node already had in its mempool or extrapool.
These stats are only collected when cmpctblock debug logging is on, otherwise they stay zero. At trace level, every requested txid is now logged in one line, not only when fewer than five were missing.
-persistmempoolv1 wrote mempool.dat in the old v1 format, without the XOR key, so a node could downgrade to v26 or earlier. v26 has been end of life since April 2025, so the option is gone. DumpMempool always writes the current format with a fresh obfuscation key, and a v1 file still loads.
mempool_compatibility.py now tests against v31.0, the last release with the flag. mempool_persist.py also checks that importmempool rejects a truncated file.
There are always changes being updated and reviewed in real-time. Here are some notable PRโs that are still up and looking for reviews.
Evicting by age can drop a transaction that could still be mined, so this PR (fixing #33510) deletes CTxMemPool::Expire and the two-week default. LimitMempoolSize now only trims to the size limit, and LoadMempool no longer skips old saved transactions.
-mempoolexpiry stays as a hidden option that only logs a warning if set. The entry_time index and mempool_expiry.py are removed.
Time-based mempool expiry has been removed, and the
-mempoolexpirystartup option no longer has any effect (a warning is logged if it is set).
IRC meeting notes
Every week on Thursday, there is an IRC meeting. Here are some short notes from that meeting.
--- Topic 1 ---
๐๐๐ถ๐ฐ๐ธ๐ถ๐ฒ๐-๐: reminder: there's no IRC meeting today as many won't be able to attend
--- Topic 2 ---
๐ฒ๐๐ด๐ฒ๐ป๐ฒ๐๐ถ๐ฒ๐ด๐ฒ๐น: there are a few obscure cases where power loss can prevent a node from being able to startup, nothing serious. how should these be handled, should I make an issue to track them? Some of these might have already been reported by the LLM audits. I've run into a number of them while fuzzing + emulating power loss with the bedrock hypervisor
๐ป๐ธ๐ฎ๐ฟ๐ฒ๐๐ป๐ถ๐ธ๐ผ๐: eugenesiegel: this reminded me of #25539 which i assume was reported by you as well
๐ป๐ธ๐ฎ๐ฟ๐ฒ๐๐ป๐ถ๐ธ๐ผ๐: there was also a mention of power loss in this recent discussion #35298
Releases
The
v32.0rc4binaries are now published: bitcoincore.org/bin/bitcoin-core-32.0/test.rc4 (tagged by sedited).
Thank you for reading. Be sure to tune in again next week for your updates on Bitcoin Core!
If there are any comments, suggestions, or errors, do not hesitate to reach out or comment.