private broadcast: bound memory use of broadcast attempts #35680

pull instagibbs wants to merge 1 commits into bitcoin:master from instagibbs:2026-07-bound_private_mem changing 8 files +244 −155

instagibbs commented at 8:12 PM on July 7, 2026: member

Rather than scale the memory usage with the total number attempts per tx to recompute necessary statistics, directly track the necessary information, leaving us with memory usage in-line with number of active peer connections and outstanding private relay txs.

Do note that this means per-peer statistics will be lost on that specific peer's disconnection.

Waiting for #35090 to be merged and I will rebase on top of it, but taking directional (N)ACKs now
DrahtBot commented at 8:12 PM on July 7, 2026: contributor


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For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35680.



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Conflicts

Reviewers, this pull request conflicts with the following ones:
- #33922 (mining: add getMemoryLoad() and track template non-mempool memory footprint by Sjors)
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fanquake added the label Private Broadcast on Jul 7, 2026

private broadcast: bound memory use of broadcast attempts

Rather than scale the memory usage with the total number
attempts per tx to recompute necessary statistics, directly
track the necessary information, leaving us with memory
usage in-line with number of active peer connections and
outstanding private relay txs.

85d109a3ef

instagibbs force-pushed on Jul 7, 2026
DrahtBot added the label CI failed on Jul 7, 2026
DrahtBot removed the label CI failed on Jul 7, 2026
fanquake commented at 8:56 AM on July 8, 2026: member

cc @vasild @andrewtoth

in src/rpc/mempool.cpp:165 in 85d109a3ef

 159 | @@ -160,7 +160,9 @@ static RPCMethod getprivatebroadcastinfo()
 160 |                                  {RPCResult::Type::STR_HEX, "wtxid", "The transaction witness hash in hex"},
 161 |                                  {RPCResult::Type::STR_HEX, "hex", "The serialized, hex-encoded transaction data"},
 162 |                                  {RPCResult::Type::NUM_TIME, "time_added", "The time this transaction was added to the private broadcast queue (seconds since epoch)"},
 163 | -                                {RPCResult::Type::ARR, "peers", "Per-peer send and acknowledgment information for this transaction",
 164 | +                                {RPCResult::Type::NUM, "num_sent", "Total number of peers this transaction was sent to so far"},
 165 | +                                {RPCResult::Type::NUM, "num_acknowledged", "Total number of peers that acknowledged reception of this transaction"},
 166 | +                                {RPCResult::Type::ARR, "peers", "Per-peer send and acknowledgment information for this transaction, for currently connected peers only",

andrewtoth commented at 1:46 PM on July 8, 2026:

If we make this change, is it worth reporting this? It will only have a value for max 3 minutes, and the received field will only ever have a value for a tiny amount of time that will require racing between receiving the PONG and disconnecting.

If we don't think we should store this data for stats a la #34707, we should remove these fields IMO. If we think they're valuable, we should instead cap this to last ~3 peers instead and just truncate the vector as we make more connections.

instagibbs commented at 5:26 PM on July 8, 2026:

A limited buffer of disconnected peer stats, in addition to all the live ones, could make sense, if that's what you're suggesting

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#35090 fuzz: add p2p_private_broadcast harness

private broadcast: bound memory use of broadcast attempts #35680

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