1. 下載Snappy庫
2. 編譯leveldb自帶的db_bench
$(CXX) $(LDFLAGS) db/db_bench.o $(LIBOBJECTS) $(TESTUTIL) -o $@
為
$(CXX) db/db_bench.o $(LIBOBJECTS) $(TESTUTIL) -o $@ $(LDFLAGS)
為了獲取更多的信息，我寫了一個簡單的測試程序來測試寫性能。
g++ src/ldbbench.cpp libleveldb.a -I../leveldb/include -o ldb_test -pthread -lsnappy
我隔10w條記錄統計一下運行時間和各層level的個數。
#include <iostream>
#include <cstdlib>
#include <sys/time.h>
#include "leveldb/db.h"
#include "leveldb/env.h"
using namespace std;
using namespace leveldb;
static inline double micro_time(){
struct timeval tim;
double ret;
gettimeofday(&tim, NULL);
ret = tim.tv_sec+(tim.tv_usec/1000000.0);
return ret;
}
int main() {
srand ( time(NULL) );
DB *db ;
Options op;
op.create_if_missing = true;
Status s = DB::Open(op,"/tmp/testdb",&db);
Env * env = Env::Default();
WritableFile *file;
env->NewWritableFile("/tmp/bench.csv",&file);
if(s.ok()){
cout << "create successfully" << endl;
WriteOptions wop;
for(int j=0;j<100;++j){
double start = micro_time();
double cost;
for(int i=0;i<100000;++i){
char key[100];
char value[100];
sprintf(key,"%d_%d",i,rand());
sprintf(value,"%d",rand());
db->Put(wop,key,value);
}
cost = micro_time()-start;
cout << "write successfully:" << j << ",costs "<<cost<<endl;
// report the status
{
//output stats information
string value;
char buffer[40];
for(int i=0;i<7;++i){
sprintf(buffer,"leveldb.num-files-at-level%d",i);
db->GetProperty(buffer,&value);
file->Append(value+",");
}
sprintf(buffer,"%f",cost);
file->Append(buffer);
file->Append("\n");
file->Sync();
}
}
cout << "write completed" << endl;
}
delete db;
file->Close();
delete file;
return 0;
}
得到結果如下：
可以看出 插入時間不穩定，一旦level 0 的文件個數達到8（leveldb在level0 sst file到達8會做流量控制），就會嚴重的影響插入速度。
數據如下： 前7欄為各level的文件個數，最后一欄為插入時間(單位second).
0,0,0,0,0,0,0,0.312044
0,0,1,0,0,0,0,0.339661
0,1,1,0,0,0,0,0.336554
1,1,1,0,0,0,0,0.338470
2,1,1,0,0,0,0,0.319139
4,1,1,0,0,0,0,0.322158
5,1,1,0,0,0,0,0.411267
6,1,1,0,0,0,0,0.452211
7,1,1,0,0,0,0,0.392227
4,6,1,0,0,0,0,0.599982
5,6,1,0,0,0,0,0.392222
6,6,1,0,0,0,0,0.426607
7,6,1,0,0,0,0,0.450604
0,9,7,0,0,0,0,1.884518
1,9,7,0,0,0,0,0.420226
2,8,8,0,0,0,0,0.395083
3,8,8,0,0,0,0,0.418100
4,7,9,0,0,0,0,0.421611
6,7,9,0,0,0,0,0.415739
7,7,9,0,0,0,0,0.407361
1,14,10,0,0,0,0,2.226791
2,14,10,0,0,0,0,0.401517
3,14,10,0,0,0,0,0.373305
4,13,11,0,0,0,0,0.419741
5,13,11,0,0,0,0,0.409911
6,12,12,0,0,0,0,0.410904
7,12,12,0,0,0,0,0.429305
0,19,15,0,0,0,0,3.586968
2,19,15,0,0,0,0,0.443083
3,18,16,0,0,0,0,0.403899
4,18,16,0,0,0,0,0.427664
5,17,17,0,0,0,0,0.398022
6,16,19,0,0,0,0,0.373106
7,16,19,0,0,0,0,0.381070
0,16,27,0,0,0,0,3.997287
1,16,27,0,0,0,0,0.415576
2,15,29,0,0,0,0,0.395088
3,15,29,0,0,0,0,0.421756
4,15,29,0,0,0,0,0.423345
5,14,30,0,0,0,0,0.443051
6,13,32,0,0,0,0,0.409214
0,21,35,0,0,0,0,3.724305
1,21,35,0,0,0,0,0.394496
2,20,36,0,0,0,0,0.400312
3,20,36,0,0,0,0,0.440494
4,19,36,0,0,0,0,0.401116
5,19,36,0,0,0,0,0.368698
6,19,36,0,0,0,0,0.392624
7,18,37,0,0,0,0,0.421263
0,20,45,0,0,0,0,5.280940
1,20,45,0,0,0,0,0.445995
2,19,46,0,0,0,0,0.427433
3,19,46,0,0,0,0,0.396355
4,19,46,0,0,0,0,0.412447
6,18,47,0,0,0,0,0.425992
7,18,47,0,0,0,0,0.409269
0,22,54,0,0,0,0,4.659271
1,22,54,0,0,0,0,0.353135
2,22,54,0,0,0,0,0.412604
3,22,54,0,0,0,0,0.387365
4,21,55,0,0,0,0,0.447579
5,20,56,0,0,0,0,0.423402
6,20,56,0,0,0,0,0.392983
7,19,58,0,0,0,0,0.372202
0,22,66,0,0,0,0,5.072227
1,22,66,0,0,0,0,0.389874
2,22,66,0,0,0,0,0.375599
4,22,66,0,0,0,0,0.405292
5,22,66,0,0,0,0,0.404367
6,22,66,0,0,0,0,0.394260
7,22,66,0,0,0,0,0.401855
0,24,77,0,0,0,0,5.980508
1,24,77,0,0,0,0,0.388424
2,24,77,0,0,0,0,0.429406
3,23,78,0,0,0,0,0.412908
4,23,78,0,0,0,0,0.428574
5,23,78,0,0,0,0,0.403336
6,22,79,0,0,0,0,0.394216
8,13,89,0,0,0,0,5.377096
1,23,89,0,0,0,0,0.816229
2,23,89,0,0,0,0,0.437396
3,23,89,0,0,0,0,0.399540
4,22,90,0,0,0,0,0.437927
5,22,90,0,0,0,0,0.424814
6,22,90,0,0,0,0,0.411747
7,21,92,0,0,0,0,0.384908
0,25,100,0,0,0,0,6.236974
1,25,100,0,0,0,0,0.403147
3,25,100,0,0,0,0,0.412086
4,25,100,0,0,0,0,0.403978
5,24,102,0,0,0,0,0.398120
6,24,102,0,0,0,0,0.374137
7,24,102,0,0,0,0,0.370625
0,22,102,10,0,0,0,6.692459
1,22,102,10,0,0,0,0.389345
2,22,102,10,0,0,0,0.411086
3,22,102,10,0,0,0,0.404387
4,21,103,10,0,0,0,0.443593
5,21,103,10,0,0,0,0.400221
6,21,103,10,0,0,0,0.414371