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Linmin's Data

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ARST打卡第206周[206/521]

 included in ARST
   5153 words   11 minutes 

Algorithm

lc1019_链表中的下一个更大节点

  • 链表中节点数为 n
  • 1 <= n <= 1e4
  • 1 <= Node.val <= 1e9

思路:

  • 因为 n 的取值范围的问题，可以O(n^2)，所以应该可以暴力法
  • 优化的方法应该是双指针，先一个找到，然后记录右指针，右指针左边的值一定小于左指针和自己。中间的值可以维护一个有序容器，multiset(注意这里删除就不要删除值，而是删除一个迭代器指针指向的位置)。空间换时间。
  • 再优化一点，就是一开始把所有值都先插入进去，然后一个个比较删除即可。时间复杂度O(nlogn)和空间复杂度是O(n)。

结果一看题解，发现确实就是典型的单调栈经典问题，惭愧了，又忘了…

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class Solution {
public:
    vector<int> nextLargerNodes(ListNode* head) {
        vector<int> ans;
        stack<pair<int, int>> s;

        ListNode* cur = head;
        int idx = -1;
        while (cur) {
            ++idx;
            ans.push_back(0);
            while (!s.empty() && s.top().first < cur->val) {
                ans[s.top().second] = cur->val;
                s.pop();
            }
            s.emplace(cur->val, idx);
            cur = cur->next;
        }

        return ans;
    }
};

Review

坚持30天僧人般严苛自律的生活_思考

博主想表达的不仅仅是自律，更多的是要体会自己内心的需求，接受好的不好的自己，倾听自己内心的声音，不是一味地逃避自己不喜欢的一面，而是要学会与它相处，体会真正的诉求，毕竟所有这些才组成了真正的我们，这些不同的人格都是为了保护我们，或者让我们更好，学会与他们相处，而不是把他们当做敌人，过多的压抑会遭到反噬，和谐的相处体会才能得到更好的效果，无论是工作还是生活中。

Tips

大佬写在工作10周年

在这个行业做的久了, 你就会越加的尊敬Oracle. 在单机存储引擎领域, Oracle 做的真的是非常的极致, 现在PolarDB 能够和Oracle PK 也只是因为赛道变了, 但是在单机存储引擎上, 我仍然觉得Oracle 很多地方值得我们学习. 所以不管别人怎么说, 我还是觉得 Oracle, AWS aurora 团队那些糟老头子比我们强, 一定有很多值得我们学习的地方, 我还是觉得数据库领域是慢工出细活, 没有所谓的灵光一闪, 只有日积月累.

RAFT加ROCKSDB重新思考

看懂了一些(比如: WAL写入基于Qurom机制进行，可以有效的规避掉慢节点。)，但是还有一些处于懵懂状态，存储行业还是学海无涯，继续学习。

Share-rocksdb6.29版本编译安装使用测试

环境说明

  • Ubuntu18.04 (Windows Subsystem for Linux, WSL2)
  • GCC4.8, C++11
  • RocksDB6.29b (RocksDB7.0以上版本需要GCC7 和 C++17了，所以这里用的是6.29b，只需要C++11, GCC4.8)

依赖安装

按照6.29b的官方教程把依赖都装好

也可以一键安装一些依赖

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## 可以先更新一下软件包的情况
## sudo apt-get update 
sudo apt-get install libsnappy-dev zlib1g-dev libbz2-dev liblz4-dev libzstd-dev libgflags-dev

静态编译安装

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make static_lib -j$(nproc)
make install-static -j$(nproc)

-j$(nproc) 是使用机器的全部CPU，根据本身机器的CPU数来合理设置，比如配置成-j$(($(nproc) / 2))

简单用例编译运行

  • 创建数据库测试目录并且编码
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cd ~/code/rocksdb
mkdir /tmp/rocksdb_tmp

 ⚡ 04/13|10:57:46  rocksdb   6.29.fb  vim test.cpp
 ⚡ 04/13|10:57:58  rocksdb   6.29.fb  cat test.cpp
#include <cstdio>
#include <string>
#include "rocksdb/db.h"
#include "rocksdb/slice.h"
#include "rocksdb/options.h"

using namespace std;
using namespace rocksdb;

const std::string PATH = "/tmp/rocksdb_tmp";
int main(){
    DB* db;
    Options options;
    options.create_if_missing = true;
    Status status = DB::Open(options, PATH, &db);
    assert(status.ok());
    Slice key("foo");
    Slice value("bar");
    std::string get_value;
    status = db->Put(WriteOptions(), key, value);
    if(status.ok()){
        status = db->Get(ReadOptions(), key, &get_value);
        if(status.ok()){
            printf("get %s success!!\n", get_value.c_str());
        }else{
            printf("get failed\n");
        }
    }else{
        printf("put failed\n");
    }
    delete db;
}
  • 进行编译运行
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 ⚡ 04/13|10:31:32  rocksdb   6.29.fb  g++ test.cpp -o test.out -std=c++11  -lrocksdb -lz -lbz2 -lsnappy -pthread -lzstd -llz4 -ldl
 ⚡ 04/13|10:33:35  rocksdb   6.29.fb  ./test.out
get bar success!!

参数 -L：表示要连接的库所在目录 (这里没用到) -l：指定链接时需要的动/静态库。 注意: 编译器查找动态连接库时有隐含的命名规则，即在给出的名字前面加上lib，后面加上.a或.so来确定库的名称。

所以编译生成的是 librocksdb.a 需要写成 -lrocksdb 的样子

中途可能会遇到的一些问题

Q: rocksdb/./util/compression.h:116: undefined reference to ZSTD_freeDCtx' A: 编译加 -lzstd, 也即g++ test.cpp -o test.out -std=c++11 -lrocksdb -lz -lbz2 -lsnappy -pthread -lzstd`

Q: rocksdb/./util/compression.h:1074: undefined reference to LZ4_compressBound' A: 同理加-llz4, 即g++ test.cpp -o test.out -std=c++11 -lrocksdb -lz -lbz2 -lsnappy -pthread -lzstd -llz4`

Q: rocksdb/env/env_posix.cc:108: undefined reference to dlclose' A: 增加动态链接选项 -ldl，即g++ test.cpp -o test.out -std=c++11 -lrocksdb -lz -lbz2 -lsnappy -pthread -lzstd -llz4 -ldl` 这里乌龙，把dl写成了ld一会儿

跑测试

编译db_bench并且简单测试脚本

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## 编译时间有点久，尽量多搞点CPU
 ⚡ 04/13|11:28:26  rocksdb   6.29.fb  make db_bench -j$(nproc)
$DEBUG_LEVEL is 1
Makefile:170: Warning: Compiling in debug mode. Don.t use the resulting binary in production
## ...很多 CC 编译
  AR       librocksdb_debug.a
/usr/bin/ar: creating librocksdb_debug.a
  CCLD     db_bench
 ⚡ 04/13|11:35:16  rocksdb   6.29.fb 
 ⚡ 04/13|11:35:16  rocksdb   6.29.fb  ./db_bench
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB:    version 6.29
Date:       Thu Apr 13 11:37:14 2023
CPU:        6 * Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz
CPUCache:   9216 KB
Keys:       16 bytes each (+ 0 bytes user-defined timestamp)
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: Snappy
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
DB path: [/tmp/rocksdbtest-0/dbbench]
fillseq      :       3.444 micros/op 290364 ops/sec;   32.1 MB/s
Please disable_auto_compactions in FillDeterministic benchmark
 ✘ ⚡ 04/13|11:39:44  rocksdb   6.29.fb  ./db_bench --disable_auto_compactions=true
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB:    version 6.29
Date:       Thu Apr 13 11:40:04 2023
CPU:        6 * Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz
CPUCache:   9216 KB
Keys:       16 bytes each (+ 0 bytes user-defined timestamp)
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: Snappy
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
DB path: [/tmp/rocksdbtest-0/dbbench]
fillseq      :       3.601 micros/op 277713 ops/sec;   30.7 MB/s
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
DB path: [/tmp/rocksdbtest-0/dbbench]
n is too small to fill 7 levels
 ✘ ⚡ 04/13|11:40:15  rocksdb   6.29.fb 

跑benchmark.sh bulkload

在 benchmark.sh 脚本中，如果没有指定 –duration 或者 –num 选项，那么 bulkload 基准测试模式将会一直运行下去，直到手动停止脚本或者遇到错误。这种情况下，测试的持续时间将会取决于数据集的大小以及 RocksDB 的写入性能。如果测试数据集较小或者 RocksDB 的写入性能较低，测试可能需要很长时间才能结束。

因此，在运行 benchmark.sh 脚本时，建议使用 –duration 或者 –num 选项来限制测试的持续时间或者测试数据集的大小。这样可以避免测试持续时间过长或者测试数据集过大导致的问题。同时，需要根据实际情况来调整测试参数以获得更好的测试效果。

比如:

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./tools/benchmark.sh bulkload --num=10000000 --value_size=100 --duration=180

在这个命令中，–duration=180 选项指定测试持续时间为 180 秒。同时，–num=10000000 选项指定测试数据集的大小为 1000 万个键值对，–value_size=100 选项指定每个值的大小为 100 字节。需要注意的是，延长测试时间可能会增加测试的负载和资源占用，因此需要根据实际情况进行调整。

下面是我的测试，第一次跑没有限定时间和文件大小，跑了很久很久才手动 ctrl+c掉，然后才想到可能需要设定时间，才找到duration参数

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mkdir /tmp/rocksdb
export DB_DIR=/tmp/rocksdb/db
export WAL_DIR=/tmp/rocksdb/wal
export TEMP=/tmp/rocksdb/tmp
export OUTPUT_DIR=/tmp/rocksdb/output

 ⚡ 04/13|11:40:15  rocksdb   6.29.fb  ./tools/benchmark.sh bulkload
===== Benchmark =====
Starting bulkload (ID: ) at Thu Apr 13 11:41:23 CST 2023
Bulk loading 8000000000 random keys
./db_bench --benchmarks=fillrandom --use_existing_db=0 --disable_auto_compactions=1 --sync=0 --max_background_compactions=16 --max_write_buffer_number=8 --allow_concurrent_memtable_write=false --max_background_flushes=7 --level0_file_num_compaction_trigger=10485760 --level0_slowdown_writes_trigger=10485760 --level0_stop_writes_trigger=10485760 --db=/tmp/rocksdb/db --wal_dir=/tmp/rocksdb/wal --num=8000000000 --num_levels=6 --key_size=20 --value_size=400 --block_size=8192 --cache_size=17179869184 --cache_numshardbits=6 --compression_max_dict_bytes=0 --compression_ratio=0.5 --compression_type=zstd --level_compaction_dynamic_level_bytes=true --bytes_per_sync=8388608 --cache_index_and_filter_blocks=0 --pin_l0_filter_and_index_blocks_in_cache=1 --benchmark_write_rate_limit=0 --hard_rate_limit=3 --rate_limit_delay_max_milliseconds=1000000 --write_buffer_size=134217728 --target_file_size_base=134217728 --max_bytes_for_level_base=1073741824 --verify_checksum=1 --delete_obsolete_files_period_micros=62914560 --max_bytes_for_level_multiplier=8 --statistics=0 --stats_per_interval=1 --stats_interval_seconds=60 --histogram=1 --memtablerep=skip_list --bloom_bits=10 --open_files=-1 --threads=1 --memtablerep=vector --allow_concurrent_memtable_write=false --disable_wal=1 --seed=1681357283 2>&1 | tee -a /tmp/rocksdb/output/benchmark_bulkload_fillrandom.log
RocksDB:    version 6.29
Date:       Thu Apr 13 11:41:23 2023
CPU:        6 * Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz
CPUCache:   9216 KB
2023/04/13-11:42:24  ... thread 0: (25745000,25745000) ops and (428780.8,428780.8) ops/second in (60.042332,60.042332) seconds

** Compaction Stats [default] **
Level    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  L0     77/0    4.20 GB   4.2      0.0     0.0      0.0       4.2      4.2       0.0   1.0      0.0     13.4    320.08            109.05        77    4.157       0      0       0.0       0.0
 Sum     77/0    4.20 GB   0.0      0.0     0.0      0.0       4.2      4.2       0.0   1.0      0.0     13.4    320.08            109.05        77    4.157       0      0       0.0       0.0
 Int      0/0    0.00 KB   0.0      0.0     0.0      0.0       4.2      4.2       0.0   1.0      0.0     13.4    320.08            109.05        77    4.157       0      0       0.0       0.0

** Compaction Stats [default] **
Priority    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
High      0/0    0.00 KB   0.0      0.0     0.0      0.0       4.2      4.2       0.0   0.0      0.0     13.4    320.08            109.05        77    4.157       0      0       0.0       0.0

## 很多日志

^C

 ⚡ 04/13|15:01:29  rocksdb   6.29.fb  ./tools/benchmark.sh bulkload --num=10000000 --value_size=100 --duration=180
===== Benchmark =====
Starting bulkload (ID: ) at Thu Apr 13 15:01:40 CST 2023
Bulk loading 8000000000 random keys
./db_bench --benchmarks=fillrandom --use_existing_db=0 --disable_auto_compactions=1 --sync=0 --max_background_compactions=16 --max_write_buffer_number=8 --allow_concurrent_memtable_write=false --max_background_flushes=7 --level0_file_num_compaction_trigger=10485760 --level0_slowdown_writes_trigger=10485760 --level0_stop_writes_trigger=10485760 --db=/tmp/rocksdb/db --wal_dir=/tmp/rocksdb/wal --num=8000000000 --num_levels=6 --key_size=20 --value_size=400 --block_size=8192 --cache_size=17179869184 --cache_numshardbits=6 --compression_max_dict_bytes=0 --compression_ratio=0.5 --compression_type=zstd --level_compaction_dynamic_level_bytes=true --bytes_per_sync=8388608 --cache_index_and_filter_blocks=0 --pin_l0_filter_and_index_blocks_in_cache=1 --benchmark_write_rate_limit=0 --hard_rate_limit=3 --rate_limit_delay_max_milliseconds=1000000 --write_buffer_size=134217728 --target_file_size_base=134217728 --max_bytes_for_level_base=1073741824 --verify_checksum=1 --delete_obsolete_files_period_micros=62914560 --max_bytes_for_level_multiplier=8 --statistics=0 --stats_per_interval=1 --stats_interval_seconds=60 --histogram=1 --memtablerep=skip_list --bloom_bits=10 --open_files=-1 --num=10000000 --value_size=100 --duration=180 --threads=1 --memtablerep=vector --allow_concurrent_memtable_write=false --disable_wal=1 --seed=1681369300 2>&1 | tee -a /tmp/rocksdb/output/benchmark_bulkload_fillrandom.log
RocksDB:    version 6.29
Date:       Thu Apr 13 15:01:47 2023
CPU:        6 * Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz
CPUCache:   9216 KB
2023/04/13-15:02:48  ... thread 0: (31184000,31184000) ops and (519717.6,519717.6) ops/second in (60.001818,60.001818) seconds

** Compaction Stats [default] **
Level    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  L0     25/0    1.29 GB   1.3      0.0     0.0      0.0       1.3      1.3       0.0   1.0      0.0      4.5    294.22             54.30        25   11.769       0      0       0.0       0.0
 Sum     25/0    1.29 GB   0.0      0.0     0.0      0.0       1.3      1.3       0.0   1.0      0.0      4.5    294.22             54.30        25   11.769       0      0       0.0       0.0
 Int      0/0    0.00 KB   0.0      0.0     0.0      0.0       1.3      1.3       0.0   1.0      0.0      4.5    294.22             54.30        25   11.769       0      0       0.0       0.0

** Compaction Stats [default] **
Priority    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
High      0/0    0.00 KB   0.0      0.0     0.0      0.0       1.3      1.3       0.0   0.0      0.0      4.5    294.22             54.30        25   11.769       0      0       0.0       0.0

Blob file count: 0, total size: 0.0 GB

Uptime(secs): 60.5 total, 57.0 interval
Flush(GB): cumulative 1.288, interval 1.288
AddFile(GB): cumulative 0.000, interval 0.000
AddFile(Total Files): cumulative 0, interval 0
AddFile(L0 Files): cumulative 0, interval 0
AddFile(Keys): cumulative 0, interval 0
Cumulative compaction: 1.29 GB write, 21.80 MB/s write, 0.00 GB read, 0.00 MB/s read, 294.2 seconds
Interval compaction: 1.29 GB write, 23.14 MB/s write, 0.00 GB read, 0.00 MB/s read, 294.2 seconds
Stalls(count): 0 level0_slowdown, 0 level0_slowdown_with_compaction, 0 level0_numfiles, 0 level0_numfiles_with_compaction, 0 stop for pending_compaction_bytes, 0 slowdown for pending_compaction_bytes, 0 memtable_compaction, 23 memtable_slowdown, interval 23 total count
Block cache LRUCache@0x55f687960330#2714 capacity: 16.00 GB collections: 1 last_copies: 1 last_secs: 0.00024 secs_since: 61
Block cache entry stats(count,size,portion): Misc(1,0.00 KB,0%)

** File Read Latency Histogram By Level [default] **

** DB Stats **
Uptime(secs): 60.5 total, 57.0 interval
Cumulative writes: 0 writes, 31M keys, 0 commit groups, 0.0 writes per commit group, ingest: 3.92 GB, 66.35 MB/s
Cumulative WAL: 0 writes, 0 syncs, 0.00 writes per sync, written: 0.00 GB, 0.00 MB/s
Cumulative stall: 00:00:35.883 H:M:S, 59.3 percent
Interval writes: 0 writes, 29M keys, 0 commit groups, 0.0 writes per commit group, ingest: 3810.79 MB, 66.85 MB/s
Interval WAL: 0 writes, 0 syncs, 0.00 writes per sync, written: 0.00 GB, 0.00 MB/s
Interval stall: 00:00:35.883 H:M:S, 63.0 percent

2023/04/13-15:03:48  ... thread 0: (27315000,58499000) ops and (455241.6,487479.8) ops/second in (60.001110,120.002928) seconds

** Compaction Stats [default] **
Level    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  L0     53/0    2.73 GB   2.7      0.0     0.0      0.0       2.8      2.8       0.0   1.0      0.0      4.1    698.07            115.65        54   12.927       0      0       0.0       0.0
 Sum     53/0    2.73 GB   0.0      0.0     0.0      0.0       2.8      2.8       0.0   1.0      0.0      4.1    698.07            115.65        54   12.927       0      0       0.0       0.0
 Int      0/0    0.00 KB   0.0      0.0     0.0      0.0       1.5      1.5       0.0   1.0      0.0      3.8    403.86             61.34        29   13.926       0      0       0.0       0.0

** Compaction Stats [default] **
Priority    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
High      0/0    0.00 KB   0.0      0.0     0.0      0.0       2.8      2.8       0.0   0.0      0.0      4.1    698.07            115.65        54   12.927       0      0       0.0       0.0

Blob file count: 0, total size: 0.0 GB

Uptime(secs): 120.5 total, 60.0 interval
Flush(GB): cumulative 2.785, interval 1.497
AddFile(GB): cumulative 0.000, interval 0.000
AddFile(Total Files): cumulative 0, interval 0
AddFile(L0 Files): cumulative 0, interval 0
AddFile(Keys): cumulative 0, interval 0
Cumulative compaction: 2.79 GB write, 23.67 MB/s write, 0.00 GB read, 0.00 MB/s read, 698.1 seconds
Interval compaction: 1.50 GB write, 25.54 MB/s write, 0.00 GB read, 0.00 MB/s read, 403.9 seconds
Stalls(count): 0 level0_slowdown, 0 level0_slowdown_with_compaction, 0 level0_numfiles, 0 level0_numfiles_with_compaction, 0 stop for pending_compaction_bytes, 0 slowdown for pending_compaction_bytes, 0 memtable_compaction, 51 memtable_slowdown, interval 28 total count
Block cache LRUCache@0x55f687960330#2714 capacity: 16.00 GB collections: 1 last_copies: 1 last_secs: 0.00024 secs_since: 121
Block cache entry stats(count,size,portion): Misc(1,0.00 KB,0%)

** File Read Latency Histogram By Level [default] **

** DB Stats **
Uptime(secs): 120.5 total, 60.0 interval
Cumulative writes: 0 writes, 58M keys, 0 commit groups, 0.0 writes per commit group, ingest: 7.35 GB, 62.50 MB/s
Cumulative WAL: 0 writes, 0 syncs, 0.00 writes per sync, written: 0.00 GB, 0.00 MB/s
Cumulative stall: 00:01:17.887 H:M:S, 64.6 percent
Interval writes: 0 writes, 27M keys, 0 commit groups, 0.0 writes per commit group, ingest: 3516.70 MB, 58.61 MB/s
Interval WAL: 0 writes, 0 syncs, 0.00 writes per sync, written: 0.00 GB, 0.00 MB/s
Interval stall: 00:00:42.004 H:M:S, 70.0 percent

2023/04/13-15:04:48  ... thread 0: (27837000,86336000) ops and (463946.1,479635.3) ops/second in (60.000503,180.003431) seconds

** Compaction Stats [default] **
Level    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  L0     82/0    4.23 GB   4.2      0.0     0.0      0.0       4.2      4.2       0.0   1.0      0.0      4.0   1076.38            170.62        82   13.127       0      0       0.0       0.0
 Sum     82/0    4.23 GB   0.0      0.0     0.0      0.0       4.2      4.2       0.0   1.0      0.0      4.0   1076.38            170.62        82   13.127       0      0       0.0       0.0
 Int      0/0    0.00 KB   0.0      0.0     0.0      0.0       1.4      1.4       0.0   1.0      0.0      3.9    378.31             54.97        28   13.511       0      0       0.0       0.0

** Compaction Stats [default] **
Priority    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
High      0/0    0.00 KB   0.0      0.0     0.0      0.0       4.2      4.2       0.0   0.0      0.0      4.0   1076.38            170.62        82   13.127       0      0       0.0       0.0

Blob file count: 0, total size: 0.0 GB

Uptime(secs): 180.5 total, 60.0 interval
Flush(GB): cumulative 4.229, interval 1.444
AddFile(GB): cumulative 0.000, interval 0.000
AddFile(Total Files): cumulative 0, interval 0
AddFile(L0 Files): cumulative 0, interval 0
AddFile(Keys): cumulative 0, interval 0
Cumulative compaction: 4.23 GB write, 23.99 MB/s write, 0.00 GB read, 0.00 MB/s read, 1076.4 seconds
Interval compaction: 1.44 GB write, 24.65 MB/s write, 0.00 GB read, 0.00 MB/s read, 378.3 seconds
Stalls(count): 0 level0_slowdown, 0 level0_slowdown_with_compaction, 0 level0_numfiles, 0 level0_numfiles_with_compaction, 0 stop for pending_compaction_bytes, 0 slowdown for pending_compaction_bytes, 0 memtable_compaction, 79 memtable_slowdown, interval 28 total count
Block cache LRUCache@0x55f687960330#2714 capacity: 16.00 GB collections: 1 last_copies: 1 last_secs: 0.00024 secs_since: 181
Block cache entry stats(count,size,portion): Misc(1,0.00 KB,0%)

** File Read Latency Histogram By Level [default] **

** DB Stats **
Uptime(secs): 180.5 total, 60.0 interval
Cumulative writes: 0 writes, 86M keys, 0 commit groups, 0.0 writes per commit group, ingest: 10.85 GB, 61.58 MB/s
Cumulative WAL: 0 writes, 0 syncs, 0.00 writes per sync, written: 0.00 GB, 0.00 MB/s
Cumulative stall: 00:02:1.031 H:M:S, 67.0 percent
Interval writes: 0 writes, 27M keys, 0 commit groups, 0.0 writes per commit group, ingest: 3583.90 MB, 59.73 MB/s
Interval WAL: 0 writes, 0 syncs, 0.00 writes per sync, written: 0.00 GB, 0.00 MB/s
Interval stall: 00:00:43.144 H:M:S, 71.9 percent

Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
Keys:       20 bytes each (+ 0 bytes user-defined timestamp)
Values:     100 bytes each (50 bytes after compression)
Entries:    10000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    1144.4 MB (estimated)
FileSize:   667.6 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: ZSTD
Compression sampling rate: 0
Memtablerep: VectorRepFactory
Perf Level: 1
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
DB path: [/tmp/rocksdb/db]
fillrandom   :       2.085 micros/op 479677 ops/sec;   54.9 MB/s
Microseconds per write:
Count: 86346999 Average: 2.0847  StdDev: 40.44
Min: 0  Median: 0.5086  Max: 30633
Percentiles: P50: 0.51 P75: 0.76 P99: 1.81 P99.9: 961.81 P99.99: 1266.70
------------------------------------------------------
[       0,       1 ] 84890082  98.313%  98.313% ####################
(       1,       2 ]   735804   0.852%  99.165%
(       2,       3 ]   298782   0.346%  99.511%
(       3,       4 ]    52267   0.061%  99.571%
(       4,       6 ]    11956   0.014%  99.585%
(       6,      10 ]     4381   0.005%  99.590%
(      10,      15 ]    13884   0.016%  99.606%
(      15,      22 ]   141096   0.163%  99.770%
(      22,      34 ]    51510   0.060%  99.829%
(      34,      51 ]    23390   0.027%  99.857%
(      51,      76 ]     9056   0.010%  99.867%
(      76,     110 ]     3030   0.004%  99.871%
(     110,     170 ]     1135   0.001%  99.872%
(     170,     250 ]      403   0.000%  99.872%
(     250,     380 ]      217   0.000%  99.873%
(     380,     580 ]      114   0.000%  99.873%
(     580,     870 ]      144   0.000%  99.873%
(     870,    1300 ]   109602   0.127% 100.000%
(    1300,    1900 ]       58   0.000% 100.000%
(    1900,    2900 ]       18   0.000% 100.000%
(    2900,    4400 ]       22   0.000% 100.000%
(    4400,    6600 ]       16   0.000% 100.000%
(    6600,    9900 ]       16   0.000% 100.000%
(    9900,   14000 ]        9   0.000% 100.000%
(   14000,   22000 ]        5   0.000% 100.000%
(   22000,   33000 ]        2   0.000% 100.000%

Compacting...
./db_bench --benchmarks=compact --use_existing_db=1 --disable_auto_compactions=1 --sync=0 --level0_file_num_compaction_trigger=4 --level0_stop_writes_trigger=20 --max_background_compactions=16 --max_write_buffer_number=8 --max_background_flushes=7 --db=/tmp/rocksdb/db --wal_dir=/tmp/rocksdb/wal --num=8000000000 --num_levels=6 --key_size=20 --value_size=400 --block_size=8192 --cache_size=17179869184 --cache_numshardbits=6 --compression_max_dict_bytes=0 --compression_ratio=0.5 --compression_type=zstd --level_compaction_dynamic_level_bytes=true --bytes_per_sync=8388608 --cache_index_and_filter_blocks=0 --pin_l0_filter_and_index_blocks_in_cache=1 --benchmark_write_rate_limit=0 --hard_rate_limit=3 --rate_limit_delay_max_milliseconds=1000000 --write_buffer_size=134217728 --target_file_size_base=134217728 --max_bytes_for_level_base=1073741824 --verify_checksum=1 --delete_obsolete_files_period_micros=62914560 --max_bytes_for_level_multiplier=8 --statistics=0 --stats_per_interval=1 --stats_interval_seconds=60 --histogram=1 --memtablerep=skip_list --bloom_bits=10 --open_files=-1 --num=10000000 --value_size=100 --duration=180 --threads=1 2>&1 | tee -a /tmp/rocksdb/output/benchmark_bulkload_compact.log
RocksDB:    version 6.29
Date:       Thu Apr 13 15:05:02 2023
CPU:        6 * Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz
CPUCache:   9216 KB
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
Keys:       20 bytes each (+ 0 bytes user-defined timestamp)
Values:     100 bytes each (50 bytes after compression)
Entries:    10000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    1144.4 MB (estimated)
FileSize:   667.6 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: ZSTD
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
DB path: [/tmp/rocksdb/db]
compact      : 60822353.000 micros/op 0 ops/sec;
Completed bulkload (ID: ) in 263 seconds
ops/sec mb/sec  Size-GB L0_GB   Sum_GB  W-Amp   W-MB/s  usec/op p50     p75     p99     p99.9   p99.99  Uptime  Stall-time      Stall%  Test    Date    Version Job-ID
479677  54.9    0.0     4.2     4.2     1.0     23.8    2.1     0.5     0.8     2       962     1267    180     00:02:1.031     67.0    bulkload        2023-04-13T15:01:47.000+08:00   6.29

测试报告简单理解

在 RocksDB 的 db_bench 基准测试工具中，测试报告会在测试结束后自动生成。报告包含了多个测试结果指标，可以用来评估 RocksDB 的读写性能以及其他指标。下面是一些常见的测试结果指标：

  • ops/sec：每秒操作数，表示 RocksDB 每秒能够执行的读写操作数量。
  • MB/s：每秒传输的数据量，表示 RocksDB 每秒能够读写的数据量。
  • Latency(at 50th/90th/99th percentile)：响应时间，表示 RocksDB 的读写操作的平均响应时间。50th、90th 和 99th percentile 分别表示操作响应时间在前 50%、90% 和 99% 的操作的响应时间。
  • Stalls(count)：表示 RocksDB 因为某些原因而停止工作的次数。

测试报告的每一行对应一次测试结果，列出了 RocksDB 在测试过程中的各项性能指标。报告的最后几行总结了测试结果，并给出了平均值和标准差等统计信息。

在评估测试报告时，需要注意不同测试模式的结果指标可能会有所不同，需要结合实际情况进行评估。同时，需要注意测试结果受多种因素影响，包括测试数据集的大小、读写操作的类型、硬件环境等，因此需要进行多次测试并综合考虑。

跑点高级特性吧

可以后续研究一下

其他(清理)

注意: 会清掉 db_bench 运行文件，所以谨慎使用

1
2

## 清理掉编译产生的很多的 *.d 文件，不影响 librocksdb.a 库的使用
make clean

参考链接

Ubuntu安装Rocksdb并调试

Updated on 2023-12-16
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