[qa] Test non-atomic chainstate writes

Adds new functional test, dbcrash.py, which uses -dbcrashratio to exercise the
logic for recovering from a crash during chainstate flush.

dbcrash.py is added to the extended tests, as it may take ~10 minutes to run

Use _Exit() instead of exit() for crash simulation

This eliminates stderr output such as:
    terminate called without an active exception
or
    Assertion failed: (!pthread_mutex_destroy(&m)), function ~recursive_mutex, file /usr/local/include/boost/thread/pthread/recursive_mutex.hpp, line 104.

Eliminating the stderr output on crash simulation allows testing with
test_runner.py, which reports a test as failed if stderr is produced.
This commit is contained in:
Suhas Daftuar 2017-06-15 17:08:48 -04:00 committed by Pieter Wuille
parent d6af06d68a
commit 176c021d08
4 changed files with 272 additions and 1 deletions

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@ -124,7 +124,7 @@ bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) {
static FastRandomContext rng;
if (rng.randrange(crash_simulate) == 0) {
LogPrintf("Simulating a crash. Goodbye.\n");
exit(0);
_Exit(0);
}
}
}

268
test/functional/dbcrash.py Executable file
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@ -0,0 +1,268 @@
#!/usr/bin/env python3
# Copyright (c) 2017 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Test recovery from a crash during chainstate writing."""
from test_framework.test_framework import BitcoinTestFramework
from test_framework.util import *
from test_framework.script import *
from test_framework.mininode import *
import random
try:
import http.client as httplib
except ImportError:
import httplib
import errno
'''
Test structure:
- 4 nodes
* node0, node1, and node2 will have different dbcrash ratios, and different
dbcache sizes
* node3 will be a regular node, with no crashing.
* The nodes will not connect to each other.
- use default test framework starting chain. initialize starting_tip_height to
tip height.
- Main loop:
* generate lots of transactions on node3, enough to fill up a block.
* uniformly randomly pick a tip height from starting_tip_height to
tip_height; with probability 1/(height_difference+4), invalidate this block.
* mine enough blocks to overtake tip_height at start of loop.
* for each node in [node0,node1,node2]:
- for each mined block:
* submit block to node
* if node crashed on/after submitting:
- restart until recovery succeeds
- check that utxo matches node3 using gettxoutsetinfo
'''
class ChainstateWriteCrashTest(BitcoinTestFramework):
def __init__(self):
super().__init__()
self.num_nodes = 4
self.setup_clean_chain = False
# Set -maxmempool=0 to turn off mempool memory sharing with dbcache
# Set -rpcservertimeout=900 to reduce socket disconnects in this
# long-running test
self.base_args = ["-limitdescendantsize=0", "-maxmempool=0", "-rpcservertimeout=900"]
# Set different crash ratios and cache sizes. Note that not all of
# -dbcache goes to pcoinsTip.
self.node0_args = ["-dbcrashratio=8", "-dbcache=4", "-dbbatchsize=200000"] + self.base_args
self.node1_args = ["-dbcrashratio=16", "-dbcache=8", "-dbbatchsize=200000"] + self.base_args
self.node2_args = ["-dbcrashratio=24", "-dbcache=16", "-dbbatchsize=200000"] + self.base_args
# Node3 is a normal node with default args, except will mine full blocks
self.node3_args = ["-blockmaxweight=4000000"]
self.extra_args = [self.node0_args, self.node1_args, self.node2_args, self.node3_args]
# We'll track some test coverage statistics
self.restart_counts = [0, 0, 0] # Track the restarts for nodes 0-2
self.crashed_on_restart = 0 # Track count of crashes during recovery
def setup_network(self):
self.setup_nodes()
# Leave them unconnected, we'll use submitblock directly in this test
# Starts up a given node id, waits for the tip to reach the given block
# hash, and calculates the utxo hash. Exceptions on startup should
# indicate node crash (due to -dbcrashratio), in which case we try again.
# Give up after 60 seconds.
# Returns the utxo hash of the given node.
def restart_node(self, node_index, expected_tip):
time_start = time.time()
while time.time() - time_start < 60:
try:
# Any of these RPC calls could throw due to node crash
self.nodes[node_index] = self.start_node(node_index, self.options.tmpdir, self.extra_args[node_index])
self.nodes[node_index].waitforblock(expected_tip)
utxo_hash = self.nodes[node_index].gettxoutsetinfo()['hash_serialized_2']
return utxo_hash
except:
# An exception here should mean the node is about to crash.
# If bitcoind exits, then try again. wait_for_node_exit()
# should raise an exception if bitcoind doesn't exit.
wait_for_node_exit(node_index, timeout=10)
self.crashed_on_restart += 1
time.sleep(1)
# If we got here, bitcoind isn't coming back up on restart. Could be a
# bug in bitcoind, or we've gotten unlucky with our dbcrash ratio --
# perhaps we generated a test case that blew up our cache?
# TODO: If this happens a lot, we should try to restart without -dbcrashratio
# and make sure that recovery happens.
raise AssertionError("Unable to successfully restart node %d in allotted time", node_index)
# Try submitting a block to the given node.
# Catch any exceptions that indicate the node has crashed.
# Returns true if the block was submitted successfully; false otherwise.
def submit_block_catch_error(self, node_index, block):
try:
self.nodes[node_index].submitblock(block)
return True
except (httplib.CannotSendRequest, httplib.RemoteDisconnected) as e:
self.log.debug("node %d submitblock raised exception: %s", node_index, e)
return False
except OSError as e:
self.log.debug("node %d submitblock raised OSError exception: errno=%s", node_index, e.errno)
if e.errno in [errno.EPIPE, errno.ECONNREFUSED, errno.ECONNRESET]:
# The node has likely crashed
return False
else:
# Unexpected exception, raise
raise
# Use submitblock to sync node3's chain with the other nodes
# If submitblock fails, restart the node and get the new utxo hash.
def sync_node3blocks(self, block_hashes):
# If any nodes crash while updating, we'll compare utxo hashes to
# ensure recovery was successful.
node3_utxo_hash = self.nodes[3].gettxoutsetinfo()['hash_serialized_2']
# Retrieve all the blocks from node3
blocks = []
for block_hash in block_hashes:
blocks.append([block_hash, self.nodes[3].getblock(block_hash, 0)])
# Deliver each block to each other node
for i in range(3):
nodei_utxo_hash = None
self.log.debug("Syncing blocks to node %d", i)
for (block_hash, block) in blocks:
# Get the block from node3, and submit to node_i
self.log.debug("submitting block %s", block_hash)
if not self.submit_block_catch_error(i, block):
# TODO: more carefully check that the crash is due to -dbcrashratio
# (change the exit code perhaps, and check that here?)
wait_for_node_exit(i, timeout=30)
self.log.debug("Restarting node %d after block hash %s", i, block_hash)
nodei_utxo_hash = self.restart_node(i, block_hash)
assert nodei_utxo_hash is not None
self.restart_counts[i] += 1
else:
# Clear it out after successful submitblock calls -- the cached
# utxo hash will no longer be correct
nodei_utxo_hash = None
# Check that the utxo hash matches node3's utxo set
# NOTE: we only check the utxo set if we had to restart the node
# after the last block submitted:
# - checking the utxo hash causes a cache flush, which we don't
# want to do every time; so
# - we only update the utxo cache after a node restart, since flushing
# the cache is a no-op at that point
if nodei_utxo_hash is not None:
self.log.debug("Checking txoutsetinfo matches for node %d", i)
assert_equal(nodei_utxo_hash, node3_utxo_hash)
# Verify that the utxo hash of each node matches node3.
# Restart any nodes that crash while querying.
def verify_utxo_hash(self):
node3_utxo_hash = self.nodes[3].gettxoutsetinfo()['hash_serialized_2']
self.log.info("Verifying utxo hash matches for all nodes")
for i in range(3):
try:
nodei_utxo_hash = self.nodes[i].gettxoutsetinfo()['hash_serialized_2']
except OSError:
# probably a crash on db flushing
nodei_utxo_hash = self.restart_node(i, self.nodes[3].getbestblockhash())
assert_equal(nodei_utxo_hash, node3_utxo_hash)
def generate_small_transactions(self, node, count, utxo_list):
FEE = 1000 # TODO: replace this with node relay fee based calculation
num_transactions = 0
random.shuffle(utxo_list)
while len(utxo_list) >= 2 and num_transactions < count:
tx = CTransaction()
input_amount = 0
for i in range(2):
utxo = utxo_list.pop()
tx.vin.append(CTxIn(COutPoint(int(utxo['txid'], 16), utxo['vout'])))
input_amount += int(utxo['amount']*COIN)
output_amount = (input_amount - FEE)//3
if output_amount <= 0:
# Sanity check -- if we chose inputs that are too small, skip
continue
for i in range(3):
tx.vout.append(CTxOut(output_amount, hex_str_to_bytes(utxo['scriptPubKey'])))
# Sign and send the transaction to get into the mempool
tx_signed_hex = node.signrawtransaction(ToHex(tx))['hex']
node.sendrawtransaction(tx_signed_hex)
num_transactions += 1
def run_test(self):
# Start by creating a lot of utxos on node3
initial_height = self.nodes[3].getblockcount()
utxo_list = create_confirmed_utxos(self.nodes[3].getnetworkinfo()['relayfee'], self.nodes[3], 5000)
self.log.info("Prepped %d utxo entries", len(utxo_list))
# Sync these blocks with the other nodes
block_hashes_to_sync = []
for height in range(initial_height+1, self.nodes[3].getblockcount()+1):
block_hashes_to_sync.append(self.nodes[3].getblockhash(height))
self.log.debug("Syncing %d blocks with other nodes", len(block_hashes_to_sync))
# Syncing the blocks could cause nodes to crash, so the test begins here.
self.sync_node3blocks(block_hashes_to_sync)
starting_tip_height = self.nodes[3].getblockcount()
# Main test loop:
# each time through the loop, generate a bunch of transactions,
# and then either mine a single new block on the tip, or some-sized reorg.
for i in range(40):
self.log.info("Iteration %d, generating 2500 transactions %s", i, self.restart_counts)
# Generate a bunch of small-ish transactions
self.generate_small_transactions(self.nodes[3], 2500, utxo_list)
# Pick a random block between current tip, and starting tip
current_height = self.nodes[3].getblockcount()
random_height = random.randint(starting_tip_height, current_height)
self.log.debug("At height %d, considering height %d", current_height, random_height)
if random_height > starting_tip_height:
# Randomly reorg from this point with some probability (1/4 for
# tip, 1/5 for tip-1, ...)
if random.random() < 1.0/(current_height + 4 - random_height):
self.log.debug("Invalidating block at height %d", random_height)
self.nodes[3].invalidateblock(self.nodes[3].getblockhash(random_height))
# Now generate new blocks until we pass the old tip height
self.log.debug("Mining longer tip")
block_hashes = self.nodes[3].generate(current_height+1-self.nodes[3].getblockcount())
self.log.debug("Syncing %d new blocks...", len(block_hashes))
self.sync_node3blocks(block_hashes)
utxo_list = self.nodes[3].listunspent()
self.log.debug("Node3 utxo count: %d", len(utxo_list))
# Check that the utxo hashes agree with node3
# Useful side effect: each utxo cache gets flushed here, so that we
# won't get crashes on shutdown at the end of the test.
self.verify_utxo_hash()
# Check the test coverage
self.log.info("Restarted nodes: %s; crashes on restart: %d", self.restart_counts, self.crashed_on_restart)
# If no nodes were restarted, we didn't test anything.
assert self.restart_counts != [0, 0, 0]
# Make sure we tested the case of crash-during-recovery.
assert self.crashed_on_restart > 0
# Warn if any of the nodes escaped restart.
for i in range(3):
if self.restart_counts[i] == 0:
self.log.warn("Node %d never crashed during utxo flush!", i)
if __name__ == "__main__":
ChainstateWriteCrashTest().main()

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@ -249,6 +249,8 @@ def wait_for_bitcoind_start(process, datadir, i, rpchost=None):
raise
time.sleep(0.25)
def wait_for_node_exit(node_index, timeout):
bitcoind_processes[node_index].wait(timeout)
def _start_node(i, dirname, extra_args=None, rpchost=None, timewait=None, binary=None, stderr=None):
"""Start a bitcoind and return RPC connection to it

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@ -124,6 +124,7 @@ EXTENDED_SCRIPTS = [
# vv Tests less than 5m vv
'maxuploadtarget.py',
'mempool_packages.py',
'dbcrash.py',
# vv Tests less than 2m vv
'bip68-sequence.py',
'getblocktemplate_longpoll.py',