mempool_limit.py raw

   1  #!/usr/bin/env python3
   2  # Copyright (c) 2014-2022 The Limenka 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  
   7  from decimal import Decimal
   8  import time
   9  
  10  from test_framework.authproxy import JSONRPCException
  11  from test_framework.mempool_util import (
  12      fill_mempool,
  13  )
  14  from test_framework.p2p import P2PTxInvStore
  15  from test_framework.test_framework import LimenkaTestFramework
  16  from test_framework.util import (
  17      assert_equal,
  18      assert_fee_amount,
  19      assert_greater_than,
  20      assert_raises_rpc_error,
  21  )
  22  from test_framework.wallet import (
  23      COIN,
  24      DEFAULT_FEE,
  25      MiniWallet,
  26  )
  27  
  28  
  29  class MempoolLimitTest(LimenkaTestFramework):
  30      def set_test_params(self):
  31          self.setup_clean_chain = True
  32          self.num_nodes = 1
  33          self.extra_args = [[
  34              "-datacarriersize=100000",
  35              "-maxmempool=5",
  36          ]]
  37          self.supports_cli = False
  38  
  39      def test_rbf_carveout_disallowed(self):
  40          node = self.nodes[0]
  41  
  42          self.log.info("Check that individually-evaluated transactions in a package don't increase package limits for other subpackage parts")
  43  
  44          # We set chain limits to 2 ancestors, 1 descendant, then try to get a parents-and-child chain of 2 in mempool
  45          #
  46          # A: Solo transaction to be RBF'd (to bump descendant limit for package later)
  47          # B: First transaction in package, RBFs A by itself under individual evaluation, which would give it +1 descendant limit
  48          # C: Second transaction in package, spends B. If the +1 descendant limit persisted, would make it into mempool
  49  
  50          self.restart_node(0, extra_args=self.extra_args[0] + ["-limitancestorcount=2", "-limitdescendantcount=1"])
  51  
  52          # Generate a confirmed utxo we will double-spend
  53          rbf_utxo = self.wallet.send_self_transfer(
  54              from_node=node,
  55              confirmed_only=True
  56          )["new_utxo"]
  57          self.generate(node, 1)
  58  
  59          # tx_A needs to be RBF'd, set minfee at set size
  60          A_vsize = 250
  61          mempoolmin_feerate = node.getmempoolinfo()["mempoolminfee"]
  62          tx_A = self.wallet.send_self_transfer(
  63              from_node=node,
  64              fee_rate=mempoolmin_feerate,
  65              target_vsize=A_vsize,
  66              utxo_to_spend=rbf_utxo,
  67              confirmed_only=True
  68          )
  69  
  70          # RBF's tx_A, is not yet submitted
  71          tx_B = self.wallet.create_self_transfer(
  72              fee=tx_A["fee"] * 4,
  73              target_vsize=A_vsize,
  74              utxo_to_spend=rbf_utxo,
  75              confirmed_only=True
  76          )
  77  
  78          # Spends tx_B's output, too big for cpfp carveout (because that would also increase the descendant limit by 1)
  79          non_cpfp_carveout_vsize = 10001  # EXTRA_DESCENDANT_TX_SIZE_LIMIT + 1
  80          tx_C = self.wallet.create_self_transfer(
  81              target_vsize=non_cpfp_carveout_vsize,
  82              fee_rate=mempoolmin_feerate,
  83              utxo_to_spend=tx_B["new_utxo"],
  84              confirmed_only=True
  85          )
  86          res = node.submitpackage([tx_B["hex"], tx_C["hex"]])
  87          assert_equal(res["package_msg"], "transaction failed")
  88          assert "too-long-mempool-chain" in res["tx-results"][tx_C["wtxid"]]["error"]
  89  
  90      def test_mid_package_eviction_success(self):
  91          node = self.nodes[0]
  92          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")
  93  
  94          # Clear mempool so it can be filled with minrelay txns
  95          self.restart_node(0, extra_args=self.extra_args[0] + ["-persistmempool=0"])
  96          assert_equal(node.getrawmempool(), [])
  97  
  98          # Restarting the node resets mempool minimum feerate
  99          assert_equal(node.getmempoolinfo()['minrelaytxfee'], node.getmempoolinfo()["mempoolminfee"])
 100  
 101          fill_mempool(self, node)
 102          current_info = node.getmempoolinfo()
 103          mempoolmin_feerate = current_info["mempoolminfee"]
 104  
 105          mempool_txids = node.getrawmempool()
 106          mempool_entries = [node.getmempoolentry(entry) for entry in mempool_txids]
 107          fees_btc_per_kvb = [entry["fees"]["base"] / (Decimal(entry["vsize"]) / 1000) for entry in mempool_entries]
 108          mempool_entry_minrate = min(fees_btc_per_kvb)
 109          mempool_entry_minrate = mempool_entry_minrate.quantize(Decimal("0.00000000"))
 110  
 111          # There is a gap, our parents will be minrate, with child bringing up descendant fee sufficiently to avoid
 112          # eviction even though parents cause eviction on their own
 113          assert_greater_than(mempool_entry_minrate, mempoolmin_feerate)
 114  
 115          package_hex = []
 116          # UTXOs to be spent by the ultimate child transaction
 117          parent_utxos = []
 118  
 119          # Series of parents that don't need CPFP and are submitted individually. Each one is large
 120          # which means in aggregate they could trigger eviction, but child submission should result
 121          # in them not being evicted
 122          parent_vsize = 25000
 123          num_big_parents = 3
 124          # Need to be large enough to trigger eviction
 125          # (note that the mempool usage of a tx is about three times its vsize)
 126          assert_greater_than(parent_vsize * num_big_parents * 3, current_info["maxmempool"] - current_info["usage"])
 127  
 128          big_parent_txids = []
 129          big_parent_wtxids = []
 130          for i in range(num_big_parents):
 131              # Last parent is higher feerate causing other parents to possibly
 132              # be evicted if trimming was allowed, which would cause the package to end up failing
 133              parent_feerate = mempoolmin_feerate + Decimal("0.00000001") if i == num_big_parents - 1 else mempoolmin_feerate
 134              parent = self.wallet.create_self_transfer(fee_rate=parent_feerate, target_vsize=parent_vsize, confirmed_only=True)
 135              parent_utxos.append(parent["new_utxo"])
 136              package_hex.append(parent["hex"])
 137              big_parent_txids.append(parent["txid"])
 138              big_parent_wtxids.append(parent["wtxid"])
 139              # There is room for each of these transactions independently
 140              assert node.testmempoolaccept([parent["hex"]])[0]["allowed"]
 141  
 142          # Create a child spending everything with an insane fee, bumping the package above mempool_entry_minrate
 143          child = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos, fee_per_output=10000000)
 144          package_hex.append(child["hex"])
 145  
 146          # Package should be submitted, temporarily exceeding maxmempool, but not evicted.
 147          package_res = None
 148          with node.assert_debug_log(expected_msgs=["rolling minimum fee bumped"]):
 149              package_res = node.submitpackage(package=package_hex, maxfeerate=0)
 150  
 151          assert_equal(package_res["package_msg"], "success")
 152  
 153          # Ensure that intra-package trimming is not happening.
 154          # Each transaction separately satisfies the current
 155          # minfee and shouldn't need package evaluation to
 156          # be included. If trimming of a parent were to happen,
 157          # package evaluation would happen to reintrodce the evicted
 158          # parent.
 159          assert_equal(len(package_res["tx-results"]), len(big_parent_wtxids) + 1)
 160          for wtxid in big_parent_wtxids + [child["wtxid"]]:
 161              assert_equal(len(package_res["tx-results"][wtxid]["fees"]["effective-includes"]), 1)
 162  
 163          # Maximum size must never be exceeded.
 164          assert_greater_than(node.getmempoolinfo()["maxmempool"], node.getmempoolinfo()["usage"])
 165  
 166          # Package found in mempool still
 167          resulting_mempool_txids = node.getrawmempool()
 168          assert child["txid"] in resulting_mempool_txids
 169          for txid in big_parent_txids:
 170              assert txid in resulting_mempool_txids
 171  
 172          # Check every evicted tx was higher feerate than parents which evicted it
 173          eviction_set = set(mempool_txids) - set(resulting_mempool_txids) - set(big_parent_txids)
 174          parent_entries = [node.getmempoolentry(entry) for entry in big_parent_txids]
 175          max_parent_feerate = max([entry["fees"]["modified"] / (Decimal(entry["vsize"]) / 1000) for entry in parent_entries])
 176          for eviction in eviction_set:
 177              assert eviction in mempool_txids
 178              for txid, entry in zip(mempool_txids, mempool_entries):
 179                  if txid == eviction:
 180                      evicted_feerate_btc_per_kvb = entry["fees"]["modified"] / (Decimal(entry["vsize"]) / 1000)
 181                      assert_greater_than(evicted_feerate_btc_per_kvb, max_parent_feerate)
 182  
 183      def test_mid_package_eviction(self):
 184          node = self.nodes[0]
 185          self.log.info("Check a package where each parent passes the current mempoolminfee but would cause eviction before package submission terminates")
 186  
 187          self.restart_node(0, extra_args=self.extra_args[0])
 188  
 189          # Restarting the node resets mempool minimum feerate
 190          assert_equal(node.getmempoolinfo()['minrelaytxfee'], Decimal('0.00000100'))
 191          assert_equal(node.getmempoolinfo()['mempoolminfee'], Decimal('0.00000100'))
 192  
 193          fill_mempool(self, node)
 194          current_info = node.getmempoolinfo()
 195          mempoolmin_feerate = current_info["mempoolminfee"]
 196  
 197          package_hex = []
 198          # UTXOs to be spent by the ultimate child transaction
 199          parent_utxos = []
 200  
 201          evicted_vsize = 2000
 202          # Mempool transaction which is evicted due to being at the "bottom" of the mempool when the
 203          # mempool overflows and evicts by descendant score. It's important that the eviction doesn't
 204          # happen in the middle of package evaluation, as it can invalidate the coins cache.
 205          #
 206          # NOTE: On 32-bit systems (i686), there's a race condition where concurrent transaction additions
 207          # can cause the mempool to repeatedly exceed the limit, causing immediate eviction of low-fee
 208          # transactions. We retry with exponential backoff to handle this scenario.
 209          mempool_evicted_tx = None
 210          max_retries = 20
 211          for attempt in range(max_retries):
 212              try:
 213                  # Brief backoff on retries to let concurrent operations settle
 214                  if attempt > 0:
 215                      backoff = min(0.05 * (2 ** (attempt - 1)), 2.0)  # Exponential backoff, max 2 seconds
 216                      self.log.info(f"Retry attempt {attempt + 1}/{max_retries} after {backoff:.2f}s backoff...")
 217                      time.sleep(backoff)
 218                      # Rescan UTXOs to recover any that failed to be added
 219                      self.wallet.rescan_utxos()
 220                      # Update minimum feerate as it may have increased during retries
 221                      mempoolmin_feerate = node.getmempoolinfo()["mempoolminfee"]
 222  
 223                  mempool_evicted_tx = self.wallet.send_self_transfer(
 224                      from_node=node,
 225                      fee_rate=mempoolmin_feerate,
 226                      target_vsize=evicted_vsize,
 227                      confirmed_only=True
 228                  )
 229                  if attempt > 0:
 230                      self.log.info(f"Successfully added transaction on attempt {attempt + 1}")
 231                  break
 232              except JSONRPCException as e:
 233                  if e.error['code'] == -26:  # mempool full or min fee not met
 234                      if attempt < max_retries - 1:
 235                          continue
 236                      else:
 237                          self.log.error(f"Failed to add transaction after {max_retries} attempts due to race condition")
 238                  raise
 239  
 240          assert mempool_evicted_tx is not None, "Failed to add transaction after retries"
 241          # Already in mempool when package is submitted.
 242          assert mempool_evicted_tx["txid"] in node.getrawmempool()
 243  
 244          # This parent spends the above mempool transaction that exists when its inputs are first
 245          # looked up, but disappears later. It is rejected for being too low fee (but eligible for
 246          # reconsideration), and its inputs are cached. When the mempool transaction is evicted, its
 247          # coin is no longer available, but the cache could still contains the tx.
 248          cpfp_parent = self.wallet.create_self_transfer(
 249              utxo_to_spend=mempool_evicted_tx["new_utxo"],
 250              fee_rate=mempoolmin_feerate / 2,
 251              confirmed_only=True)
 252          package_hex.append(cpfp_parent["hex"])
 253          parent_utxos.append(cpfp_parent["new_utxo"])
 254          assert_equal(node.testmempoolaccept([cpfp_parent["hex"]])[0]["reject-reason"], "mempool min fee not met")
 255  
 256          self.wallet.rescan_utxos()
 257  
 258          # Series of parents that don't need CPFP and are submitted individually. Each one is large and
 259          # high feerate, which means they should trigger eviction but not be evicted.
 260          parent_vsize = 25000
 261          num_big_parents = 3
 262          # Need to be large enough to trigger eviction
 263          # (note that the mempool usage of a tx is about three times its vsize)
 264          assert_greater_than(parent_vsize * num_big_parents * 3, current_info["maxmempool"] - current_info["usage"])
 265          parent_feerate = 10 * mempoolmin_feerate
 266  
 267          big_parent_txids = []
 268          for i in range(num_big_parents):
 269              parent = self.wallet.create_self_transfer(fee_rate=parent_feerate, target_vsize=parent_vsize, confirmed_only=True)
 270              parent_utxos.append(parent["new_utxo"])
 271              package_hex.append(parent["hex"])
 272              big_parent_txids.append(parent["txid"])
 273              # There is room for each of these transactions independently
 274              assert node.testmempoolaccept([parent["hex"]])[0]["allowed"]
 275  
 276          # Create a child spending everything, bumping cpfp_parent just above mempool minimum
 277          # feerate. It's important not to bump too much as otherwise mempool_evicted_tx would not be
 278          # evicted, making this test much less meaningful.
 279          approx_child_vsize = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos)["tx"].get_vsize()
 280          cpfp_fee = (mempoolmin_feerate / 1000) * (cpfp_parent["tx"].get_vsize() + approx_child_vsize) - cpfp_parent["fee"]
 281          # Specific number of satoshis to fit within a small window. The parent_cpfp + child package needs to be
 282          # - When there is mid-package eviction, high enough feerate to meet the new mempoolminfee
 283          # - When there is no mid-package eviction, low enough feerate to be evicted immediately after submission.
 284          magic_satoshis = 120
 285          cpfp_satoshis = int(cpfp_fee * COIN) + magic_satoshis
 286  
 287          child = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos, fee_per_output=cpfp_satoshis)
 288          package_hex.append(child["hex"])
 289  
 290          # Package should be submitted, temporarily exceeding maxmempool, and then evicted.
 291          with node.assert_debug_log(expected_msgs=["rolling minimum fee bumped"]):
 292              assert_equal(node.submitpackage(package_hex)["package_msg"], "transaction failed")
 293  
 294          # Maximum size must never be exceeded.
 295          assert_greater_than(node.getmempoolinfo()["maxmempool"], node.getmempoolinfo()["usage"])
 296  
 297          # Evicted transaction and its descendants must not be in mempool.
 298          resulting_mempool_txids = node.getrawmempool()
 299          assert mempool_evicted_tx["txid"] not in resulting_mempool_txids
 300          assert cpfp_parent["txid"] not in resulting_mempool_txids
 301          assert child["txid"] not in resulting_mempool_txids
 302          for txid in big_parent_txids:
 303              assert txid in resulting_mempool_txids
 304  
 305      def test_mid_package_replacement(self):
 306          node = self.nodes[0]
 307          self.log.info("Check a package where an early tx depends on a later-replaced mempool tx")
 308  
 309          self.restart_node(0, extra_args=self.extra_args[0])
 310  
 311          # Restarting the node resets mempool minimum feerate
 312          assert_equal(node.getmempoolinfo()['minrelaytxfee'], node.getmempoolinfo()["mempoolminfee"])
 313  
 314          fill_mempool(self, node)
 315          current_info = node.getmempoolinfo()
 316          mempoolmin_feerate = current_info["mempoolminfee"]
 317  
 318          # Mempool transaction which is evicted due to being at the "bottom" of the mempool when the
 319          # mempool overflows and evicts by descendant score. It's important that the eviction doesn't
 320          # happen in the middle of package evaluation, as it can invalidate the coins cache.
 321          double_spent_utxo = self.wallet.get_utxo(confirmed_only=True)
 322          replaced_tx = self.wallet.send_self_transfer(
 323              from_node=node,
 324              utxo_to_spend=double_spent_utxo,
 325              fee_rate=mempoolmin_feerate,
 326              confirmed_only=True
 327          )
 328          # Already in mempool when package is submitted.
 329          assert replaced_tx["txid"] in node.getrawmempool()
 330  
 331          # This parent spends the above mempool transaction that exists when its inputs are first
 332          # looked up, but disappears later. It is rejected for being too low fee (but eligible for
 333          # reconsideration), and its inputs are cached. When the mempool transaction is evicted, its
 334          # coin is no longer available, but the cache could still contain the tx.
 335          cpfp_parent = self.wallet.create_self_transfer(
 336              utxo_to_spend=replaced_tx["new_utxo"],
 337              fee_rate=mempoolmin_feerate - Decimal('0.000001'),
 338              confirmed_only=True)
 339  
 340          self.wallet.rescan_utxos()
 341  
 342          # Parent that replaces the parent of cpfp_parent.
 343          replacement_tx = self.wallet.create_self_transfer(
 344              utxo_to_spend=double_spent_utxo,
 345              fee_rate=10*mempoolmin_feerate,
 346              confirmed_only=True
 347          )
 348          parent_utxos = [cpfp_parent["new_utxo"], replacement_tx["new_utxo"]]
 349  
 350          # Create a child spending everything, CPFPing the low-feerate parent.
 351          approx_child_vsize = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos)["tx"].get_vsize()
 352          cpfp_fee = (2 * mempoolmin_feerate / 1000) * (cpfp_parent["tx"].get_vsize() + approx_child_vsize) - cpfp_parent["fee"]
 353          child = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos, fee_per_output=int(cpfp_fee * COIN))
 354          # It's very important that the cpfp_parent is before replacement_tx so that its input (from
 355          # replaced_tx) is first looked up *before* replacement_tx is submitted.
 356          package_hex = [cpfp_parent["hex"], replacement_tx["hex"], child["hex"]]
 357  
 358          # Package should be submitted, temporarily exceeding maxmempool, and then evicted.
 359          res = node.submitpackage(package_hex)
 360          assert_equal(res["package_msg"], "transaction failed")
 361          assert len([tx_res for _, tx_res in res["tx-results"].items() if "error" in tx_res and tx_res["error"] == "bad-txns-inputs-missingorspent"])
 362  
 363          # Maximum size must never be exceeded.
 364          assert_greater_than(node.getmempoolinfo()["maxmempool"], node.getmempoolinfo()["usage"])
 365  
 366          resulting_mempool_txids = node.getrawmempool()
 367          # The replacement should be successful.
 368          assert replacement_tx["txid"] in resulting_mempool_txids
 369          # The replaced tx and all of its descendants must not be in mempool.
 370          assert replaced_tx["txid"] not in resulting_mempool_txids
 371          assert cpfp_parent["txid"] not in resulting_mempool_txids
 372          assert child["txid"] not in resulting_mempool_txids
 373  
 374  
 375      def run_test(self):
 376          node = self.nodes[0]
 377          self.wallet = MiniWallet(node)
 378          miniwallet = self.wallet
 379  
 380          # Generate coins needed to create transactions in the subtests (excluding coins used in fill_mempool).
 381          self.generate(miniwallet, 20)
 382  
 383          relayfee = node.getnetworkinfo()['relayfee']
 384          self.log.info('Check that mempoolminfee is minrelaytxfee')
 385          assert_equal(node.getmempoolinfo()['minrelaytxfee'], node.getmempoolinfo()["mempoolminfee"])
 386  
 387          fill_mempool(self, node)
 388  
 389          # 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
 390          self.log.info('Create a mempool tx that will not pass mempoolminfee')
 391          assert_raises_rpc_error(-26, "mempool min fee not met", miniwallet.send_self_transfer, from_node=node, fee_rate=relayfee)
 392  
 393          self.log.info("Check that submitpackage allows cpfp of a parent below mempool min feerate")
 394          node = self.nodes[0]
 395          peer = node.add_p2p_connection(P2PTxInvStore())
 396  
 397          # Package with 2 parents and 1 child. One parent has a high feerate due to modified fees,
 398          # another is below the mempool minimum feerate but bumped by the child.
 399          tx_poor = miniwallet.create_self_transfer(fee_rate=relayfee)
 400          tx_rich = miniwallet.create_self_transfer(fee=0, fee_rate=0)
 401          node.prioritisetransaction(tx_rich["txid"], 0, int(DEFAULT_FEE * COIN))
 402          package_txns = [tx_rich, tx_poor]
 403          coins = [tx["new_utxo"] for tx in package_txns]
 404          tx_child = miniwallet.create_self_transfer_multi(utxos_to_spend=coins, fee_per_output=10000) #DEFAULT_FEE
 405          package_txns.append(tx_child)
 406  
 407          submitpackage_result = node.submitpackage([tx["hex"] for tx in package_txns])
 408          assert_equal(submitpackage_result["package_msg"], "success")
 409  
 410          rich_parent_result = submitpackage_result["tx-results"][tx_rich["wtxid"]]
 411          poor_parent_result = submitpackage_result["tx-results"][tx_poor["wtxid"]]
 412          child_result = submitpackage_result["tx-results"][tx_child["tx"].getwtxid()]
 413          assert_fee_amount(poor_parent_result["fees"]["base"], tx_poor["tx"].get_vsize(), relayfee)
 414          assert_equal(rich_parent_result["fees"]["base"], 0)
 415          assert_equal(child_result["fees"]["base"], DEFAULT_FEE)
 416          # The "rich" parent does not require CPFP so its effective feerate is just its individual feerate.
 417          assert_fee_amount(DEFAULT_FEE, tx_rich["tx"].get_vsize(), rich_parent_result["fees"]["effective-feerate"])
 418          assert_equal(rich_parent_result["fees"]["effective-includes"], [tx_rich["wtxid"]])
 419          # The "poor" parent and child's effective feerates are the same, composed of their total
 420          # fees divided by their combined vsize.
 421          package_fees = poor_parent_result["fees"]["base"] + child_result["fees"]["base"]
 422          package_vsize = tx_poor["tx"].get_vsize() + tx_child["tx"].get_vsize()
 423          assert_fee_amount(package_fees, package_vsize, poor_parent_result["fees"]["effective-feerate"])
 424          assert_fee_amount(package_fees, package_vsize, child_result["fees"]["effective-feerate"])
 425          assert_equal([tx_poor["wtxid"], tx_child["tx"].getwtxid()], poor_parent_result["fees"]["effective-includes"])
 426          assert_equal([tx_poor["wtxid"], tx_child["tx"].getwtxid()], child_result["fees"]["effective-includes"])
 427  
 428          # The node will broadcast each transaction, still abiding by its peer's fee filter
 429          peer.wait_for_broadcast([tx["tx"].getwtxid() for tx in package_txns])
 430  
 431          self.log.info("Check a package that passes mempoolminfee but is evicted immediately after submission")
 432          mempoolmin_feerate = node.getmempoolinfo()["mempoolminfee"]
 433          current_mempool = node.getrawmempool(verbose=False)
 434          worst_feerate_btcvb = Decimal("21000000")
 435          for txid in current_mempool:
 436              entry = node.getmempoolentry(txid)
 437              worst_feerate_btcvb = min(worst_feerate_btcvb, entry["fees"]["descendant"] / entry["descendantsize"])
 438          # Needs to be large enough to trigger eviction
 439          # (note that the mempool usage of a tx is about three times its vsize)
 440          target_vsize_each = 50000
 441          assert_greater_than(target_vsize_each * 2 * 3, node.getmempoolinfo()["maxmempool"] - node.getmempoolinfo()["usage"])
 442          # Should be a true CPFP: parent's feerate is just below mempool min feerate
 443          parent_feerate = mempoolmin_feerate - Decimal("0.0000001")  # 0.01 sats/vbyte below min feerate
 444          # Parent + child is above mempool minimum feerate
 445          child_feerate = (worst_feerate_btcvb * 1000) - Decimal("0.0000001")  # 0.01 sats/vbyte below worst feerate
 446          # However, when eviction is triggered, these transactions should be at the bottom.
 447          # This assertion assumes parent and child are the same size.
 448          miniwallet.rescan_utxos()
 449          tx_parent_just_below = miniwallet.create_self_transfer(fee_rate=parent_feerate, target_vsize=target_vsize_each)
 450          tx_child_just_above = miniwallet.create_self_transfer(utxo_to_spend=tx_parent_just_below["new_utxo"], fee_rate=child_feerate, target_vsize=target_vsize_each)
 451          # This package ranks below the lowest descendant package in the mempool
 452          package_fee = tx_parent_just_below["fee"] + tx_child_just_above["fee"]
 453          package_vsize = tx_parent_just_below["tx"].get_vsize() + tx_child_just_above["tx"].get_vsize()
 454          assert_greater_than(worst_feerate_btcvb, package_fee / package_vsize)
 455          assert_greater_than(mempoolmin_feerate, tx_parent_just_below["fee"] / (tx_parent_just_below["tx"].get_vsize()))
 456          assert_greater_than(package_fee / package_vsize, mempoolmin_feerate / 1000)
 457          res = node.submitpackage([tx_parent_just_below["hex"], tx_child_just_above["hex"]])
 458          for wtxid in [tx_parent_just_below["wtxid"], tx_child_just_above["wtxid"]]:
 459              assert_equal(res["tx-results"][wtxid]["error"], "mempool full")
 460  
 461          self.log.info('Test passing a value below the minimum (5 MB) to -maxmempool throws an error')
 462          self.stop_node(0)
 463          self.nodes[0].assert_start_raises_init_error(["-maxmempool=4"], "Error: -maxmempool must be at least 5 MB")
 464  
 465          self.test_mid_package_eviction_success()
 466          self.test_mid_package_replacement()
 467          self.test_mid_package_eviction()
 468          self.test_rbf_carveout_disallowed()
 469  
 470  
 471  if __name__ == '__main__':
 472      MempoolLimitTest(__file__).main()
 473