5602cc7ccf
db929893ef0bc86ea2708cdbcf41152240cd7c73 Faster -reindex by initially deserializing only headers (Larry Ruane)
c72de9990ae8f1744006d9c852023b882d5ed80c util: add CBufferedFile::SkipTo() to move ahead in the stream (Larry Ruane)
48a68908ba3d5e077cda7bd1e908b923fbead824 Add LoadExternalBlockFile() benchmark (Larry Ruane)
Pull request description:
### Background
During the first part of reindexing, `LoadExternalBlockFile()` sequentially reads raw blocks from the `blocks/blk00nnn.dat` files (rather than receiving them from peers, as with initial block download) and eventually adds all of them to the block index. When an individual block is initially read, it can't be immediately added unless all its ancestors have been added, which is rare (only about 8% of the time), because the blocks are not sorted by height. When the block can't be immediately added to the block index, its disk location is saved in a map so it can be added later. When its parent is later added to the block index, `LoadExternalBlockFile()` reads and deserializes the block from disk a second time and adds it to the block index. Most blocks (92%) get deserialized twice.
### This PR
During the initial read, it's rarely useful to deserialize the entire block; only the header is needed to determine if the block can be added to the block index immediately. This change to `LoadExternalBlockFile()` initially deserializes only a block's header, then deserializes the entire block only if it can be added immediately. This reduces reindex time on mainnet by 7 hours on a Raspberry Pi, which translates to around a 25% reduction in the first part of reindexing (adding blocks to the index), and about a 6% reduction in overall reindex time.
Summary: The performance gain is the result of deserializing each block only once, except its header which is deserialized twice, but the header is only 80 bytes.
ACKs for top commit:
andrewtoth:
ACK db929893ef0bc86ea2708cdbcf41152240cd7c73
achow101:
ACK db929893ef0bc86ea2708cdbcf41152240cd7c73
aureleoules:
ACK db929893ef0bc86ea2708cdbcf41152240cd7c73 - minor changes and new benchmark since last review
theStack:
re-ACK db929893ef0bc86ea2708cdbcf41152240cd7c73
stickies-v:
re-ACK db929893e
Tree-SHA512: 5a5377192c11edb5b662e18f511c9beb8f250bc88aeadf2f404c92c3232a7617bade50477ebf16c0602b9bd3b68306d3ee7615de58acfd8cae664d28bb7b0136
Unit tests
The sources in this directory are unit test cases. Boost includes a unit testing framework, and since Bitcoin Core already uses Boost, it makes sense to simply use this framework rather than require developers to configure some other framework (we want as few impediments to creating unit tests as possible).
The build system is set up to compile an executable called test_bitcoin
that runs all of the unit tests. The main source file for the test library is found in
util/setup_common.cpp.
Compiling/running unit tests
Unit tests will be automatically compiled if dependencies were met in ./configure
and tests weren't explicitly disabled.
After configuring, they can be run with make check.
To run the unit tests manually, launch src/test/test_bitcoin. To recompile
after a test file was modified, run make and then run the test again. If you
modify a non-test file, use make -C src/test to recompile only what's needed
to run the unit tests.
To add more unit tests, add BOOST_AUTO_TEST_CASE functions to the existing
.cpp files in the test/ directory or add new .cpp files that
implement new BOOST_AUTO_TEST_SUITE sections.
To run the GUI unit tests manually, launch src/qt/test/test_bitcoin-qt
To add more GUI unit tests, add them to the src/qt/test/ directory and
the src/qt/test/test_main.cpp file.
Running individual tests
test_bitcoin accepts the command line arguments from the boost framework.
For example, to run just the getarg_tests suite of tests:
test_bitcoin --log_level=all --run_test=getarg_tests
log_level controls the verbosity of the test framework, which logs when a
test case is entered, for example. test_bitcoin also accepts the command
line arguments accepted by bitcoind. Use -- to separate both types of
arguments:
test_bitcoin --log_level=all --run_test=getarg_tests -- -printtoconsole=1
The -printtoconsole=1 after the two dashes redirects the debug log, which
would normally go to a file in the test datadir
(BasicTestingSetup::m_path_root), to the standard terminal output.
... or to run just the doubledash test:
test_bitcoin --run_test=getarg_tests/doubledash
Run test_bitcoin --help for the full list.
Adding test cases
To add a new unit test file to our test suite you need
to add the file to src/Makefile.test.include. The pattern is to create
one test file for each class or source file for which you want to create
unit tests. The file naming convention is <source_filename>_tests.cpp
and such files should wrap their tests in a test suite
called <source_filename>_tests. For an example of this pattern,
see uint256_tests.cpp.
Logging and debugging in unit tests
make check will write to a log file foo_tests.cpp.log and display this file
on failure. For running individual tests verbosely, refer to the section
above.
To write to logs from unit tests you need to use specific message methods
provided by Boost. The simplest is BOOST_TEST_MESSAGE.
For debugging you can launch the test_bitcoin executable with gdb or lldb and
start debugging, just like you would with any other program:
gdb src/test/test_bitcoin
Segmentation faults
If you hit a segmentation fault during a test run, you can diagnose where the fault
is happening by running gdb ./src/test/test_bitcoin and then using the bt command
within gdb.
Another tool that can be used to resolve segmentation faults is valgrind.
If for whatever reason you want to produce a core dump file for this fault, you can do
that as well. By default, the boost test runner will intercept system errors and not
produce a core file. To bypass this, add --catch_system_errors=no to the
test_bitcoin arguments and ensure that your ulimits are set properly (e.g. ulimit -c unlimited).
Running the tests and hitting a segmentation fault should now produce a file called core
(on Linux platforms, the file name will likely depend on the contents of
/proc/sys/kernel/core_pattern).
You can then explore the core dump using
gdb src/test/test_bitcoin core
(gbd) bt # produce a backtrace for where a segfault occurred