azat

// Gist to check possible issues with MADV_DONTNEED
// For example it does not supported by qemu user
// There is a patch for this [1], but it hasn't been applied.
//   [1]: https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg05422.html

#include <sys/mman.h>
#include <stdio.h>
#include <stddef.h>
#include <assert.h>
#include <string.h>

azat

// gist for showing that rand() with global lock is slower ~60x times
// (came to this for librdkafa random partitioning with producer per group, and eventually program has ~1200 threads)
//
// $ g++ -DRAND -o rand -O3 -pthread rand.cpp
// $ g++ -DRAND_R -o rand_r -O3 -pthread rand.cpp
//
// $ time ./rand
//
// real    0m2.336s
// user    0m2.685s

azat

#!/usr/bin/env bash

# XXX: cannot use expect since we need two clients
# XXX: requires bash 4.4+

function assert()
{
    if ! "$@"; then
        echo "'$*' failed" >&2
        exit 1

azat

select version();
-- ┌─version()───┐
-- │ 20.3.15.133 │
-- └─────────────┘

create table ranges_data engine=Memory() as select number key, number value from numbers(100);
create dictionary default.ranges_dict (key UInt64, value UInt64 default 1) primary key key source(clickhouse(host '127.0.0.1' port 9000 table 'ranges_data' db 'default' user 'default' password '')) lifetime(0) layout(cache(size_in_cells 100));
create table dist as system.one engine=Distributed('test_cluster_two_shards', system, one, dictGetUInt64('default.ranges_dict', 'value', toUInt64(dummy)));

SELECT *

azat

/// https://github.com/aosp-mirror/platform_bionic/blob/master/benchmarks/atomic_benchmark.cpp

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0

azat

SELECT *
FROM system.distribution_queue
FORMAT Vertical

Query id: bb17b27d-c681-4826-8eb6-607a960414f3

Row 1:
──────
database:              default
table:                 dist

azat

#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>
#include <string.h>

void* mmap_hint()
{

azat

[global]
size=512m
blocksize=32k
timeout=60
numjobs=1
invalidate=1 ; invalidate page-cache (set it explicitly, even though default is true)

[read_mmap]
stonewall
ioengine=mmap

azat

<?xml version="1.0"?>
<yandex>
    <logger>
        <level>trace</level>
        <console>true</console>
    </logger>

    <tcp_port>9000</tcp_port>

    <path>./</path>

azat

/// clang++ -O2 -g3 -isystem /src/ch/clickhouse/contrib/boost -fsanitize-memory-track-origins -fsanitize=memory test-msan-3.cpp -o test-msan-3; MSAN_OPTIONS='abort_on_error=1 poison_in_dtor=1' ./test-msan-3
/// clang++ -O2 -g3 -fsanitize-memory-track-origins -fsanitize=memory test-msan-3.cpp -o test-msan-3; MSAN_OPTIONS='abort_on_error=1 poison_in_dtor=1' ./test-msan-3

#include <boost/container/small_vector.hpp>
#include <algorithm>

template <class T, std::size_t N,
          typename Allocator = boost::container::new_allocator<T>>
using small_vector = boost::container::small_vector<T, N, Allocator>;