READ THE CODE

Inside Bitcoin

The code behind the network, with room to understand it.

Stable release v32.1bitcoin/bitcoin · f0de87f04062 ↗3,020 source files · 47.5 MB stored on the server440 file guides

Release published 2026-10-28 · Snapshot fetched 2026-11-01. Latest stable release at fetch time; development branches and Git history are excluded. Only the selected code window and visible folders load here.

16,298 bytes · SHA-256 87816e1101f6cbcf… · View upstream ↗

1#!/usr/bin/env python3
2# Copyright (c) 2014-present The Bitcoin Core developers
3# Distributed under the MIT software license, see the accompanying
4# file COPYING or http://www.opensource.org/licenses/mit-license.php.
5"""Test mempool limiting together/eviction with the wallet."""
6
7from decimal import Decimal
8import time
9
10from test_framework.mempool_util import (
11    fill_mempool,
12)
13from test_framework.p2p import P2PTxInvStore
14from test_framework.test_framework import BitcoinTestFramework
15from test_framework.util import (
16    assert_equal,
17    assert_fee_amount,
18    assert_greater_than,
19    assert_raises_rpc_error,
20)
21from test_framework.wallet import (
22    COIN,
23    DEFAULT_FEE,
24    MiniWallet,
25)
26
27
28class MempoolLimitTest(BitcoinTestFramework):
29    def set_test_params(self):
30        self.setup_clean_chain = True
31        self.num_nodes = 1
32        self.extra_args = [[
33            "-maxmempool=5",
34        ]]
35
36    def test_mid_package_eviction_success(self):
37        node = self.nodes[0]
38        self.log.info("Check a package where each parent passes the current mempoolminfee but a parent could be evicted before getting child's descendant feerate")
39
40        # Clear mempool so it can be filled with minrelay txns
41        self.restart_node(0, extra_args=self.extra_args[0] + ["-persistmempool=0"])
42        assert_equal(node.getrawmempool(), [])
43
44        # Restarting the node resets mempool minimum feerate
45        assert_equal(node.getmempoolinfo()['minrelaytxfee'], node.getmempoolinfo()["mempoolminfee"])
46
47        fill_mempool(self, node)
48        current_info = node.getmempoolinfo()
49        mempoolmin_feerate = current_info["mempoolminfee"]
50
51        mempool_txids = node.getrawmempool()
52        mempool_entries = [node.getmempoolentry(entry) for entry in mempool_txids]
53        fees_btc_per_kvb = [entry["fees"]["base"] / (Decimal(entry["vsize"]) / 1000) for entry in mempool_entries]
54        mempool_entry_minrate = min(fees_btc_per_kvb)
55        mempool_entry_minrate = mempool_entry_minrate.quantize(Decimal("0.00000000"))
56
57        # There is a gap, our parents will be minrate, with child bringing up descendant fee sufficiently to avoid
58        # eviction even though parents cause eviction on their own
59        assert_greater_than(mempool_entry_minrate, mempoolmin_feerate)
60
61        package_hex = []
62        # UTXOs to be spent by the ultimate child transaction
63        parent_utxos = []
64
65        # Series of parents that don't need CPFP and are submitted individually. Each one is large
66        # which means in aggregate they could trigger eviction, but child submission should result
67        # in them not being evicted
68        parent_vsize = 25000
69        num_big_parents = 3
70        # Need to be large enough to trigger eviction
71        # (note that the mempool usage of a tx is about three times its vsize)
72        assert_greater_than(parent_vsize * num_big_parents * 3, current_info["maxmempool"] - current_info["bytes"])
73
74        big_parent_txids = []
75        big_parent_wtxids = []
76        for i in range(num_big_parents):
77            # Last parent is higher feerate causing other parents to possibly
78            # be evicted if trimming was allowed, which would cause the package to end up failing
79            parent_feerate = mempoolmin_feerate + Decimal("0.00000001") if i == num_big_parents - 1 else mempoolmin_feerate
80            parent = self.wallet.create_self_transfer(fee_rate=parent_feerate, target_vsize=parent_vsize, confirmed_only=True)
81            parent_utxos.append(parent["new_utxo"])
82            package_hex.append(parent["hex"])
83            big_parent_txids.append(parent["txid"])
84            big_parent_wtxids.append(parent["wtxid"])
85            # There is room for each of these transactions independently
86            assert node.testmempoolaccept([parent["hex"]])[0]["allowed"]
87
88        # Create a child spending everything with an insane fee, bumping the package above mempool_entry_minrate
89        child = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos, fee_per_output=10000000)
90        package_hex.append(child["hex"])
91
92        # Package should be submitted, temporarily exceeding maxmempool, but not evicted.
93        package_res = None
94        with node.assert_debug_log(expected_msgs=["rolling minimum fee bumped"]):
95            package_res = node.submitpackage(package=package_hex, maxfeerate=0)
96
97        assert_equal(package_res["package_msg"], "success")
98
99        # Ensure that intra-package trimming is not happening.
100        # Each transaction separately satisfies the current
101        # minfee and shouldn't need package evaluation to
102        # be included. If trimming of a parent were to happen,
103        # package evaluation would happen to reintrodce the evicted
104        # parent.
105        assert_equal(len(package_res["tx-results"]), len(big_parent_wtxids) + 1)
106        for wtxid in big_parent_wtxids + [child["wtxid"]]:
107            assert_equal(len(package_res["tx-results"][wtxid]["fees"]["effective-includes"]), 1)
108
109        # Maximum size must never be exceeded.
110        assert_greater_than(node.getmempoolinfo()["maxmempool"], node.getmempoolinfo()["bytes"])
111
112        # Package found in mempool still
113        resulting_mempool_txids = node.getrawmempool()
114        assert child["txid"] in resulting_mempool_txids
115        for txid in big_parent_txids:
116            assert txid in resulting_mempool_txids
117
118        # Check every evicted tx was higher feerate than parents which evicted it
119        eviction_set = set(mempool_txids) - set(resulting_mempool_txids) - set(big_parent_txids)
120        parent_entries = [node.getmempoolentry(entry) for entry in big_parent_txids]
121        max_parent_feerate = max([entry["fees"]["modified"] / (Decimal(entry["vsize"]) / 1000) for entry in parent_entries])
122        for eviction in eviction_set:
123            assert eviction in mempool_txids
124            for txid, entry in zip(mempool_txids, mempool_entries):
125                if txid == eviction:
126                    evicted_feerate_btc_per_kvb = entry["fees"]["modified"] / (Decimal(entry["vsize"]) / 1000)
127                    assert_greater_than(evicted_feerate_btc_per_kvb, max_parent_feerate)
128
129    def test_mid_package_replacement(self):
130        node = self.nodes[0]
131        self.log.info("Check a package where an early tx depends on a later-replaced mempool tx")
132
133        self.restart_node(0, extra_args=self.extra_args[0])
134
135        # Restarting the node resets mempool minimum feerate
136        assert_equal(node.getmempoolinfo()['minrelaytxfee'], node.getmempoolinfo()["mempoolminfee"])
137
138        fill_mempool(self, node)
139        current_info = node.getmempoolinfo()
140        mempoolmin_feerate = current_info["mempoolminfee"]
141
142        # Mempool transaction is replaced by a package transaction.
143        double_spent_utxo = self.wallet.get_utxo(confirmed_only=True)
144        replaced_tx = self.wallet.send_self_transfer(
145            from_node=node,
146            utxo_to_spend=double_spent_utxo,
147            fee_rate=mempoolmin_feerate,
148            confirmed_only=True
149        )
150        # Already in mempool when package is submitted.
151        assert replaced_tx["txid"] in node.getrawmempool()
152
153        # This parent spends the above mempool transaction that exists when its inputs are first
154        # looked up, but will disappear if the replacement occurs. It is rejected for being too low fee (but eligible for
155        # reconsideration), and its inputs are cached. When the mempool transaction is replaced, its
156        # coin is no longer available, but the cache could still contain the tx.
157        cpfp_parent = self.wallet.create_self_transfer(
158            utxo_to_spend=replaced_tx["new_utxo"],
159            fee_rate=mempoolmin_feerate - Decimal('0.000001'),
160            confirmed_only=True)
161
162        self.wallet.rescan_utxos()
163
164        # Parent that replaces the parent of cpfp_parent.
165        replacement_tx = self.wallet.create_self_transfer(
166            utxo_to_spend=double_spent_utxo,
167            fee_rate=10*mempoolmin_feerate,
168            confirmed_only=True
169        )
170        parent_utxos = [cpfp_parent["new_utxo"], replacement_tx["new_utxo"]]
171
172        # Create a child spending everything, CPFPing the low-feerate parent.
173        approx_child_vsize = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos)["tx"].get_vsize()
174        cpfp_fee = (2 * mempoolmin_feerate / 1000) * (cpfp_parent["tx"].get_vsize() + approx_child_vsize) - cpfp_parent["fee"]
175        child = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos, fee_per_output=int(cpfp_fee * COIN))
176        # It's very important that the cpfp_parent is before replacement_tx so that its input (from
177        # replaced_tx) is first looked up *before* replacement_tx is submitted.
178        package_hex = [cpfp_parent["hex"], replacement_tx["hex"], child["hex"]]
179
180        # Package should be submitted, temporarily exceeding maxmempool, and then evicted.
181        res = node.submitpackage(package_hex)
182        assert_equal(res["package_msg"], "transaction failed")
183        assert "bad-txns-inputs-missingorspent" in [tx_res["error"] for _, tx_res in res["tx-results"].items() if "error" in tx_res]
184
185        # Maximum size must never be exceeded.
186        assert_greater_than(node.getmempoolinfo()["maxmempool"], node.getmempoolinfo()["bytes"])
187
188        resulting_mempool_txids = node.getrawmempool()
189        # The replacement should be successful.
190        assert replacement_tx["txid"] in resulting_mempool_txids
191        # The replaced tx and all of its descendants must not be in mempool.
192        assert replaced_tx["txid"] not in resulting_mempool_txids
193        assert cpfp_parent["txid"] not in resulting_mempool_txids
194        assert child["txid"] not in resulting_mempool_txids
195
196
197    def run_test(self):
198        node = self.nodes[0]
199        self.wallet = MiniWallet(node)
200        miniwallet = self.wallet
201
202        # Generate coins needed to create transactions in the subtests (excluding coins used in fill_mempool).
203        self.generate(miniwallet, 20)
204
205        relayfee = node.getnetworkinfo()['relayfee']
206        self.log.info('Check that mempoolminfee is minrelaytxfee')
207        assert_equal(node.getmempoolinfo()['minrelaytxfee'], node.getmempoolinfo()["mempoolminfee"])
208
209        node.setmocktime(int(time.time())-3600)
210        fill_mempool(self, node)
211        node.setmocktime(0) # bump time forward so the rate limit buckets refresh and don't block broadcast
212
213        # Deliberately try to create a tx with a fee less than the minimum mempool fee to assert that it does not get added to the mempool
214        self.log.info('Create a mempool tx that will not pass mempoolminfee')
215        assert_raises_rpc_error(-26, "mempool min fee not met", miniwallet.send_self_transfer, from_node=node, fee_rate=relayfee)
216
217        self.log.info("Check that submitpackage allows cpfp of a parent below mempool min feerate")
218        node = self.nodes[0]
219        peer = node.add_p2p_connection(P2PTxInvStore())
220
221        # Package with 2 parents and 1 child. One parent has a high feerate due to modified fees,
222        # another is below the mempool minimum feerate but bumped by the child.
223        tx_poor = miniwallet.create_self_transfer(fee_rate=relayfee)
224        tx_rich = miniwallet.create_self_transfer(fee=0, fee_rate=0)
225        node.prioritisetransaction(tx_rich["txid"], 0, int(DEFAULT_FEE * COIN))
226        package_txns = [tx_rich, tx_poor]
227        coins = [tx["new_utxo"] for tx in package_txns]
228        tx_child = miniwallet.create_self_transfer_multi(utxos_to_spend=coins, fee_per_output=10000) #DEFAULT_FEE
229        package_txns.append(tx_child)
230
231        submitpackage_result = node.submitpackage([tx["hex"] for tx in package_txns])
232        assert_equal(submitpackage_result["package_msg"], "success")
233
234        rich_parent_result = submitpackage_result["tx-results"][tx_rich["wtxid"]]
235        poor_parent_result = submitpackage_result["tx-results"][tx_poor["wtxid"]]
236        child_result = submitpackage_result["tx-results"][tx_child["tx"].wtxid_hex]
237        assert_fee_amount(poor_parent_result["fees"]["base"], tx_poor["tx"].get_vsize(), relayfee)
238        assert_equal(rich_parent_result["fees"]["base"], 0)
239        assert_equal(child_result["fees"]["base"], DEFAULT_FEE)
240        # The "rich" parent does not require CPFP so its effective feerate is just its individual feerate.
241        assert_fee_amount(DEFAULT_FEE, tx_rich["tx"].get_vsize(), rich_parent_result["fees"]["effective-feerate"])
242        assert_equal(rich_parent_result["fees"]["effective-includes"], [tx_rich["wtxid"]])
243        # The "poor" parent and child's effective feerates are the same, composed of their total
244        # fees divided by their combined vsize.
245        package_fees = poor_parent_result["fees"]["base"] + child_result["fees"]["base"]
246        package_vsize = tx_poor["tx"].get_vsize() + tx_child["tx"].get_vsize()
247        assert_fee_amount(package_fees, package_vsize, poor_parent_result["fees"]["effective-feerate"])
248        assert_fee_amount(package_fees, package_vsize, child_result["fees"]["effective-feerate"])
249        assert_equal([tx_poor["wtxid"], tx_child["tx"].wtxid_hex], poor_parent_result["fees"]["effective-includes"])
250        assert_equal([tx_poor["wtxid"], tx_child["tx"].wtxid_hex], child_result["fees"]["effective-includes"])

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/init.cpp

src/crypto/sha256.cpp

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/util/chaintype.cpp

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/net_permissions.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/rpc/util.h

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/util/rbf.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/any.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

src/clientversion.cpp

src/common/signmessage.cpp

src/compat/assumptions.h

src/compat/byteswap.h

src/deploymentinfo.cpp

src/deploymentinfo.h

src/deploymentstatus.cpp

src/deploymentstatus.h

src/dummywallet.cpp

src/external_signer.h

src/init/bitcoin-gui.cpp

src/init/bitcoin-node.cpp

src/init/bitcoin-qt.cpp

src/init/bitcoin-wallet.cpp

src/init/bitcoind.cpp

src/init/common.h

src/interfaces/init.h

src/interfaces/ipc.h

src/key_io.h

src/logging/categories.h

src/logging/timer.h

src/mapport.h

src/musig.h

src/net_permissions.h

src/netgroup.h

src/netmessagemaker.h

src/node/chainstatemanager_args.cpp

src/node/connection_types.h

src/node/context.h

src/node/interface_ui.h

src/node/mempool_args.cpp

src/node/mining_args.cpp

src/node/minisketchwrapper.cpp

src/node/txreconciliation.h

src/policy/fees/estimator_args.cpp

src/policy/fees/estimator_args.h

src/policy/fees/estimator_man.cpp

src/policy/fees/estimator_man.h

src/policy/packages.h

src/policy/rbf.h

src/policy/truc_policy.h

src/pow.h

src/primitives/block.cpp

src/randomenv.h

src/rest.h

src/script/keyorigin.h

src/script/parsing.cpp

src/script/parsing.h

src/script/script_error.h

src/script/sigcache.cpp

src/script/sigcache.h

src/script/solver.h

src/script/verify_flags.h

src/semaphore_grant.h

src/signet.h

src/span.h

src/support/allocators/secure.h

src/support/allocators/zeroafterfree.h

src/util/tokenpipe.cpp

src/util/translation.h

src/util/vector.h

src/versionbits.h

src/versionbits_impl.h

src/wallet/external_signer_scriptpubkeyman.h

src/wallet/fees.h

src/wallet/load.h

src/wallet/receive.h

src/wallet/rpc/wallet.h

src/wallet/types.h

src/walletinitinterface.h

src/zmq/zmqabstractnotifier.cpp

Independent explanations by MyBitcoinExplorer. Not affiliated with or endorsed by Bitcoin Core. Guides are educational and do not replace the source or its tests.

Bitcoin Core source © its contributors, distributed under the MIT license. Original notices and bundled third-party licenses are retained in the source tree.