b9f77ba12b
Summary: It's usually hard for users to set a value of options.delayed_write_rate. With this diff, after slowdown condition triggers, we greedily reduce write rate if estimated pending compaction bytes increase. If estimated compaction pending bytes drop, we increase the write rate. Test Plan: Add a unit test Test with db_bench setting: TEST_TMPDIR=/dev/shm/ ./db_bench --benchmarks=fillrandom -num=10000000 --soft_pending_compaction_bytes_limit=1000000000 --hard_pending_compaction_bytes_limit=3000000000 --delayed_write_rate=100000000 and make sure without the commit, write stop will happen, but with the commit, it will not happen. Reviewers: igor, anthony, rven, yhchiang, kradhakrishnan, IslamAbdelRahman Reviewed By: IslamAbdelRahman Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D52131
100 lines
3.1 KiB
C++
100 lines
3.1 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#pragma once
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#include <stdint.h>
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#include <memory>
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namespace rocksdb {
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class Env;
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class WriteControllerToken;
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// WriteController is controlling write stalls in our write code-path. Write
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// stalls happen when compaction can't keep up with write rate.
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// All of the methods here (including WriteControllerToken's destructors) need
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// to be called while holding DB mutex
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class WriteController {
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public:
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explicit WriteController(uint64_t _delayed_write_rate = 1024u * 1024u * 32u)
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: total_stopped_(0),
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total_delayed_(0),
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bytes_left_(0),
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last_refill_time_(0) {
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set_delayed_write_rate(_delayed_write_rate);
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}
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~WriteController() = default;
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// When an actor (column family) requests a stop token, all writes will be
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// stopped until the stop token is released (deleted)
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std::unique_ptr<WriteControllerToken> GetStopToken();
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// When an actor (column family) requests a delay token, total delay for all
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// writes to the DB will be controlled under the delayed write rate. Every
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// write needs to call GetDelay() with number of bytes writing to the DB,
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// which returns number of microseconds to sleep.
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std::unique_ptr<WriteControllerToken> GetDelayToken(
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uint64_t delayed_write_rate);
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// these two metods are querying the state of the WriteController
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bool IsStopped() const;
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bool NeedsDelay() const { return total_delayed_ > 0; }
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// return how many microseconds the caller needs to sleep after the call
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// num_bytes: how many number of bytes to put into the DB.
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// Prerequisite: DB mutex held.
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uint64_t GetDelay(Env* env, uint64_t num_bytes);
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void set_delayed_write_rate(uint64_t write_rate) {
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// avoid divide 0
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if (write_rate == 0) {
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write_rate = 1u;
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}
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delayed_write_rate_ = write_rate;
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}
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uint64_t delayed_write_rate() const { return delayed_write_rate_; }
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private:
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friend class WriteControllerToken;
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friend class StopWriteToken;
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friend class DelayWriteToken;
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int total_stopped_;
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int total_delayed_;
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uint64_t bytes_left_;
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uint64_t last_refill_time_;
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uint64_t delayed_write_rate_;
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};
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class WriteControllerToken {
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public:
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explicit WriteControllerToken(WriteController* controller)
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: controller_(controller) {}
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virtual ~WriteControllerToken() {}
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protected:
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WriteController* controller_;
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private:
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// no copying allowed
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WriteControllerToken(const WriteControllerToken&) = delete;
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void operator=(const WriteControllerToken&) = delete;
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};
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class StopWriteToken : public WriteControllerToken {
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public:
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explicit StopWriteToken(WriteController* controller)
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: WriteControllerToken(controller) {}
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virtual ~StopWriteToken();
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};
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class DelayWriteToken : public WriteControllerToken {
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public:
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explicit DelayWriteToken(WriteController* controller)
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: WriteControllerToken(controller) {}
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virtual ~DelayWriteToken();
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};
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} // namespace rocksdb
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