dc5d8e33af
This reverts commit 1726b1d0cc.
Reverting this patch turns our SSTable access counter into a miss counter only.
The estimated histogram always starts its first bucket at 1, so by marking cache
accesses we will be wrongly feeding "1" into the buckets.
Notice that this is not yet ideal: nodetool is supposed to show a histogram of
all reads, and by doing this we are changing its meaning slightly. Workloads
that serve mostly from cache will be distorted towards their misses.
The real solution is to use a different histogram, but we will need to enforce
a newer version of nodetool for that: the current issue is that nodetool expects
an EstimatedHistogram in a specific format in the other side.
Conflicts:
row_cache.hh
Message-Id: <a599fa9e949766e7c9697450ae34fc28e881e90a.1472742276.git.glauber@scy
lladb.com>
Signed-off-by: Glauber Costa <glauber@scylladb.com>
261 lines
10 KiB
C++
261 lines
10 KiB
C++
/*
|
|
* Copyright (C) 2015 ScyllaDB
|
|
*/
|
|
|
|
/*
|
|
* This file is part of Scylla.
|
|
*
|
|
* Scylla is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU Affero General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* Scylla is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <core/distributed.hh>
|
|
#include <core/app-template.hh>
|
|
#include <core/sstring.hh>
|
|
#include <core/thread.hh>
|
|
|
|
#include "utils/managed_bytes.hh"
|
|
#include "utils/logalloc.hh"
|
|
#include "row_cache.hh"
|
|
#include "log.hh"
|
|
#include "schema_builder.hh"
|
|
#include "memtable.hh"
|
|
|
|
#include "disk-error-handler.hh"
|
|
|
|
thread_local disk_error_signal_type commit_error;
|
|
thread_local disk_error_signal_type general_disk_error;
|
|
|
|
static
|
|
partition_key new_key(schema_ptr s) {
|
|
static thread_local int next = 0;
|
|
return partition_key::from_single_value(*s, to_bytes(sprint("key%d", next++)));
|
|
}
|
|
|
|
static
|
|
clustering_key new_ckey(schema_ptr s) {
|
|
static thread_local int next = 0;
|
|
return clustering_key::from_single_value(*s, to_bytes(sprint("ckey%d", next++)));
|
|
}
|
|
|
|
int main(int argc, char** argv) {
|
|
namespace bpo = boost::program_options;
|
|
app_template app;
|
|
app.add_options()
|
|
("debug", "enable debug logging");
|
|
|
|
return app.run(argc, argv, [&app] {
|
|
if (app.configuration().count("debug")) {
|
|
logging::logger_registry().set_all_loggers_level(logging::log_level::debug);
|
|
}
|
|
|
|
// This test is supposed to verify that when we're low on memory but
|
|
// we still have plenty of evictable memory in cache, we should be
|
|
// able to populate cache with large mutations This test works only
|
|
// with seastar's allocator.
|
|
return seastar::async([] {
|
|
auto s = schema_builder("ks", "cf")
|
|
.with_column("pk", bytes_type, column_kind::partition_key)
|
|
.with_column("ck", bytes_type, column_kind::clustering_key)
|
|
.with_column("v", bytes_type, column_kind::regular_column)
|
|
.build();
|
|
|
|
auto mt0 = make_lw_shared<memtable>(s);
|
|
|
|
cache_tracker tracker;
|
|
row_cache cache(s, mt0->as_data_source(), mt0->as_key_source(), tracker);
|
|
|
|
auto mt = make_lw_shared<memtable>(s);
|
|
std::vector<dht::decorated_key> keys;
|
|
|
|
size_t cell_size = 1024;
|
|
size_t row_count = 40 * 1024; // 40M mutations
|
|
size_t large_cell_size = cell_size * row_count;
|
|
|
|
auto make_small_mutation = [&] {
|
|
mutation m(new_key(s), s);
|
|
m.set_clustered_cell(new_ckey(s), "v", data_value(bytes(bytes::initialized_later(), cell_size)), 1);
|
|
return m;
|
|
};
|
|
|
|
auto make_large_mutation = [&] {
|
|
mutation m(new_key(s), s);
|
|
m.set_clustered_cell(new_ckey(s), "v", data_value(bytes(bytes::initialized_later(), large_cell_size)), 2);
|
|
return m;
|
|
};
|
|
|
|
for (int i = 0; i < 10; i++) {
|
|
auto key = dht::global_partitioner().decorate_key(*s, new_key(s));
|
|
|
|
mutation m1(key, s);
|
|
m1.set_clustered_cell(new_ckey(s), "v", data_value(bytes(bytes::initialized_later(), cell_size)), 1);
|
|
cache.populate(m1);
|
|
|
|
// Putting large mutations into the memtable. Should take about row_count*cell_size each.
|
|
mutation m2(key, s);
|
|
for (size_t j = 0; j < row_count; j++) {
|
|
m2.set_clustered_cell(new_ckey(s), "v", data_value(bytes(bytes::initialized_later(), cell_size)), 2);
|
|
}
|
|
|
|
mt->apply(m2);
|
|
keys.push_back(key);
|
|
}
|
|
|
|
auto reclaimable_memory = [] {
|
|
return memory::stats().free_memory() + logalloc::shard_tracker().occupancy().free_space();
|
|
};
|
|
|
|
std::cout << "memtable occupancy: " << mt->occupancy() << "\n";
|
|
std::cout << "Cache occupancy: " << tracker.region().occupancy() << "\n";
|
|
std::cout << "Reclaimable memory: " << reclaimable_memory() << "\n";
|
|
|
|
// We need to have enough Free memory to copy memtable into cache
|
|
// When this assertion fails, increase amount of memory
|
|
assert(mt->occupancy().used_space() < reclaimable_memory());
|
|
|
|
auto checker = [](const partition_key& key) {
|
|
return partition_presence_checker_result::maybe_exists;
|
|
};
|
|
|
|
std::deque<dht::decorated_key> cache_stuffing;
|
|
auto fill_cache_to_the_top = [&] {
|
|
std::cout << "Filling up memory with evictable data\n";
|
|
while (true) {
|
|
// Ensure that entries matching memtable partitions are evicted
|
|
// last, we want to hit the merge path in row_cache::update()
|
|
for (auto&& key : keys) {
|
|
cache.touch(key);
|
|
}
|
|
auto occupancy_before = tracker.region().occupancy().used_space();
|
|
auto m = make_small_mutation();
|
|
cache_stuffing.push_back(m.decorated_key());
|
|
cache.populate(m);
|
|
if (tracker.region().occupancy().used_space() <= occupancy_before) {
|
|
break;
|
|
}
|
|
}
|
|
std::cout << "Shuffling..\n";
|
|
// Evict in random order to create fragmentation.
|
|
std::random_shuffle(cache_stuffing.begin(), cache_stuffing.end());
|
|
for (auto&& key : cache_stuffing) {
|
|
cache.touch(key);
|
|
}
|
|
// Ensure that entries matching memtable partitions are evicted
|
|
// last, we want to hit the merge path in row_cache::update()
|
|
for (auto&& key : keys) {
|
|
cache.touch(key);
|
|
}
|
|
std::cout << "Reclaimable memory: " << reclaimable_memory() << "\n";
|
|
std::cout << "Cache occupancy: " << tracker.region().occupancy() << "\n";
|
|
};
|
|
|
|
std::deque<std::unique_ptr<char[]>> stuffing;
|
|
auto fragment_free_space = [&] {
|
|
stuffing.clear();
|
|
std::cout << "Reclaimable memory: " << reclaimable_memory() << "\n";
|
|
std::cout << "Free memory: " << memory::stats().free_memory() << "\n";
|
|
std::cout << "Cache occupancy: " << tracker.region().occupancy() << "\n";
|
|
|
|
// Induce memory fragmentation by taking down cache segments,
|
|
// which should be evicted in random order, and inducing high
|
|
// waste level in them. Should leave around up to 100M free,
|
|
// but no LSA segment should fit.
|
|
for (unsigned i = 0; i < 100 * 1024 * 1024 / (logalloc::segment_size / 2); ++i) {
|
|
stuffing.emplace_back(std::make_unique<char[]>(logalloc::segment_size / 2 + 1));
|
|
}
|
|
|
|
std::cout << "After fragmenting:\n";
|
|
std::cout << "Reclaimable memory: " << reclaimable_memory() << "\n";
|
|
std::cout << "Free memory: " << memory::stats().free_memory() << "\n";
|
|
std::cout << "Cache occupancy: " << tracker.region().occupancy() << "\n";
|
|
};
|
|
|
|
fill_cache_to_the_top();
|
|
|
|
fragment_free_space();
|
|
|
|
cache.update(*mt, checker).get();
|
|
|
|
stuffing.clear();
|
|
cache_stuffing.clear();
|
|
|
|
// Verify that all mutations from memtable went through
|
|
for (auto&& key : keys) {
|
|
auto range = query::partition_range::make_singular(key);
|
|
auto reader = cache.make_reader(s, range);
|
|
auto mo = mutation_from_streamed_mutation(reader().get0()).get0();
|
|
assert(mo);
|
|
assert(mo->partition().live_row_count(*s) ==
|
|
row_count + 1 /* one row was already in cache before update()*/);
|
|
}
|
|
|
|
std::cout << "Testing reading from cache.\n";
|
|
|
|
fill_cache_to_the_top();
|
|
|
|
for (auto&& key : keys) {
|
|
cache.touch(key);
|
|
}
|
|
|
|
for (auto&& key : keys) {
|
|
auto range = query::partition_range::make_singular(key);
|
|
auto reader = cache.make_reader(s, range);
|
|
auto mo = reader().get0();
|
|
assert(mo);
|
|
}
|
|
|
|
std::cout << "Testing reading when memory can't be reclaimed.\n";
|
|
// We want to check that when we really can't reserve memory, allocating_section
|
|
// throws rather than enter infinite loop.
|
|
{
|
|
stuffing.clear();
|
|
cache_stuffing.clear();
|
|
tracker.clear();
|
|
|
|
// eviction victims
|
|
for (unsigned i = 0; i < logalloc::segment_size / cell_size; ++i) {
|
|
cache.populate(make_small_mutation());
|
|
}
|
|
|
|
const mutation& m = make_large_mutation();
|
|
auto range = query::partition_range::make_singular(m.decorated_key());
|
|
|
|
cache.populate(m);
|
|
|
|
logalloc::shard_tracker().reclaim_all_free_segments();
|
|
|
|
{
|
|
logalloc::reclaim_lock _(tracker.region());
|
|
try {
|
|
while (true) {
|
|
stuffing.emplace_back(std::make_unique<char[]>(logalloc::segment_size));
|
|
}
|
|
} catch (const std::bad_alloc&) {
|
|
//expected
|
|
}
|
|
}
|
|
|
|
try {
|
|
auto reader = cache.make_reader(s, range);
|
|
assert(!reader().get0());
|
|
auto evicted_from_cache = logalloc::segment_size + large_cell_size;
|
|
new char[evicted_from_cache + logalloc::segment_size];
|
|
assert(false); // The test is not invoking the case which it's supposed to test
|
|
} catch (const std::bad_alloc&) {
|
|
// expected
|
|
}
|
|
}
|
|
});
|
|
});
|
|
}
|