Files
scylladb/streaming/stream_transfer_task.cc
Asias He c70faa4f23 streaming: Reduce memory usage when sending mutations
Limit disk bandwidth to 5MB/s to emulate a slow disk:
echo "8:0 5000000" >
/cgroup/blkio/limit/blkio.throttle.write_bps_device
echo "8:0 5000000" >
/cgroup/blkio/limit/blkio.throttle.read_bps_device

Start scylla node 1 with low memory:
scylla -c 1 -m 128M --auto-bootstrap false

Run c-s:
taskset -c 7 cassandra-stress write duration=5m cl=ONE -schema
'replication(factor=1)' -pop seq=1..100000  -rate threads=20
limit=2000/s -node 127.0.0.1

Start scylla node 2 with low memory:
scylla -c 1 -m 128M --auto-bootstrap true

Without this patch, I saw std::bad_alloc during streaming

ERROR 2016-06-01 14:31:00,196 [shard 0] storage_proxy - exception during
mutation write to 127.0.0.1: std::bad_alloc (std::bad_alloc)
...
ERROR 2016-06-01 14:31:10,172 [shard 0] database - failed to move
memtable to cache: std::bad_alloc (std::bad_alloc)
...

To fix:

1. Apply the streaming mutation limiter before we read the mutation into
memory to avoid wasting memory holding the mutation which we can not
send.

2. Reduce the parallelism of sending streaming mutations. Before we send each
range in parallel, after we send each range one by one.

   before: nr_vnode * nr_shard * (send_info + cf.make_reader memory usage)

   after: nr_shard * (send_info + cf.make_reader memory usage)

We can at least save memory usage by the factor of nr_vnode, 256 by
default.

In my setup, fix 1) alone is not enough, with both fix 1) and 2), I saw
no std::bad_alloc. Also, I did not see streaming bandwidth dropped due
to 2).

In addition, I tested grow_cluster_test.py:GrowClusterTest.test_grow_3_to_4,
as described:

https://github.com/scylladb/scylla/issues/1270#issuecomment-222585375

With this patch, I saw no std::bad_alloc any more.

Fixes: #1270

Message-Id: <7703cf7a9db40e53a87f0f7b5acbb03fff2daf43.1464785542.git.asias@scylladb.com>
(cherry picked from commit 206955e47c)
2016-06-02 11:18:59 +03:00

170 lines
7.5 KiB
C++

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Modified by ScyllaDB
* 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 "log.hh"
#include "streaming/stream_detail.hh"
#include "streaming/stream_transfer_task.hh"
#include "streaming/stream_session.hh"
#include "streaming/stream_manager.hh"
#include "mutation_reader.hh"
#include "frozen_mutation.hh"
#include "mutation.hh"
#include "message/messaging_service.hh"
#include "range.hh"
#include "dht/i_partitioner.hh"
#include "service/priority_manager.hh"
#include <boost/range/irange.hpp>
namespace streaming {
extern logging::logger sslog;
stream_transfer_task::stream_transfer_task(shared_ptr<stream_session> session, UUID cf_id, std::vector<range<dht::token>> ranges, long total_size)
: stream_task(session, cf_id)
, _ranges(std::move(ranges))
, _total_size(total_size) {
}
stream_transfer_task::~stream_transfer_task() = default;
struct send_info {
database& db;
utils::UUID plan_id;
utils::UUID cf_id;
query::partition_range pr;
net::messaging_service::msg_addr id;
uint32_t dst_cpu_id;
size_t mutations_nr{0};
semaphore mutations_done{0};
bool error_logged = false;
send_info(database& db_, utils::UUID plan_id_, utils::UUID cf_id_,
query::partition_range pr_, net::messaging_service::msg_addr id_,
uint32_t dst_cpu_id_)
: db(db_)
, plan_id(plan_id_)
, cf_id(cf_id_)
, pr(pr_)
, id(id_)
, dst_cpu_id(dst_cpu_id_) {
}
};
future<stop_iteration> do_send_mutations(auto si, auto fm) {
sslog.debug("[Stream #{}] SEND STREAM_MUTATION to {}, cf_id={}", si->plan_id, si->id, si->cf_id);
auto fm_size = fm.representation().size();
net::get_local_messaging_service().send_stream_mutation(si->id, si->plan_id, std::move(fm), si->dst_cpu_id).then([si, fm_size] {
sslog.debug("[Stream #{}] GOT STREAM_MUTATION Reply from {}", si->plan_id, si->id.addr);
get_local_stream_manager().update_progress(si->plan_id, si->id.addr, progress_info::direction::OUT, fm_size);
si->mutations_done.signal();
}).handle_exception([si] (auto ep) {
// There might be larger number of STREAM_MUTATION inflight.
// Log one error per column_family per range
if (!si->error_logged) {
si->error_logged = true;
sslog.error("[Stream #{}] stream_transfer_task: Fail to send STREAM_MUTATION to {}: {}", si->plan_id, si->id, ep);
}
si->mutations_done.broken();
});
return make_ready_future<stop_iteration>(stop_iteration::no);
}
future<> send_mutations(auto si) {
auto& cf = si->db.find_column_family(si->cf_id);
auto& priority = service::get_local_streaming_read_priority();
return do_with(cf.make_reader(cf.schema(), si->pr, query::no_clustering_key_filtering, priority), [si] (auto& reader) {
return repeat([si, &reader] {
return get_local_stream_manager().mutation_send_limiter().wait().then([si, &reader] {
return reader().then([si] (auto mopt) {
if (mopt && si->db.column_family_exists(si->cf_id)) {
si->mutations_nr++;
auto fm = frozen_mutation(*mopt);
return do_send_mutations(si, std::move(fm));
} else {
return make_ready_future<stop_iteration>(stop_iteration::yes);
}
});
}).finally([] {
get_local_stream_manager().mutation_send_limiter().signal();
});
});
}).then([si] {
return si->mutations_done.wait(si->mutations_nr);
});
}
void stream_transfer_task::start() {
auto plan_id = session->plan_id();
auto cf_id = this->cf_id;
auto id = net::messaging_service::msg_addr{session->peer, session->dst_cpu_id};
sslog.debug("[Stream #{}] stream_transfer_task: cf_id={}", plan_id, cf_id);
do_for_each(_ranges.begin(), _ranges.end(), [this, plan_id, cf_id, id] (auto range) {
unsigned shard_begin = range.start() ? dht::shard_of(range.start()->value()) : 0;
unsigned shard_end = range.end() ? dht::shard_of(range.end()->value()) + 1 : smp::count;
auto cf_id = this->cf_id;
auto dst_cpu_id = this->session->dst_cpu_id;
auto pr = query::to_partition_range(range);
auto shard_range = boost::irange<unsigned>(shard_begin, shard_end);
sslog.debug("[Stream #{}] stream_transfer_task: cf_id={}, shard_begin={} shard_end={}", plan_id, cf_id, shard_begin, shard_end);
return parallel_for_each(shard_range.begin(), shard_range.end(),
[this, plan_id, cf_id, id, dst_cpu_id, pr] (unsigned shard) {
sslog.debug("[Stream #{}] stream_transfer_task: cf_id={}, invoke_on shard={}", plan_id, cf_id, shard);
return this->session->get_db().invoke_on(shard, [plan_id, cf_id, id, dst_cpu_id, pr] (database& db) {
// Send mutations on related shards, do not capture this
auto si = make_lw_shared<send_info>(db, plan_id, cf_id, pr, id, dst_cpu_id);
return send_mutations(si);
});
});
}).then([this, plan_id, cf_id, id] {
sslog.debug("[Stream #{}] SEND STREAM_MUTATION_DONE to {}, cf_id={}", plan_id, id, cf_id);
return session->ms().send_stream_mutation_done(id, plan_id, _ranges,
cf_id, session->dst_cpu_id).handle_exception([plan_id, id, cf_id] (auto ep) {
sslog.error("[Stream #{}] stream_transfer_task: Fail to send STREAM_MUTATION_DONE to {}: {}", plan_id, id, ep);
std::rethrow_exception(ep);
});
}).then([this, id, plan_id, cf_id] {
sslog.debug("[Stream #{}] GOT STREAM_MUTATION_DONE Reply from {}", plan_id, id.addr);
session->start_keep_alive_timer();
session->transfer_task_completed(cf_id);
}).handle_exception([this, plan_id, id] (auto ep){
sslog.error("[Stream #{}] stream_transfer_task: Fail to send to {}: {}", plan_id, id, ep);
this->session->on_error();
});
}
} // namespace streaming