FlatBuffers发布时，顺便也公布了它的性能数据，具体数据请见Benchmark。
它的测试用例由以下数据构成"a set of about 10 objects containing an array, 4 strings, and a large variety of int/float scalar values of all sizes, meant to be representative of game data, e.g. a scene format."
我感觉这样测试如同儿戏，便自己设计了一个测试用例，主要关注CPU计算时间和内存空间占用两个指标，参考对象是protobuf。
测试用例为：序列化一个通讯录personal_info_list（table），通讯录可以认为是有每个人的信息(personal_info)的集合。每个人信息personal_info(table)有：个人id(uint)、名字(string)、年龄(byte)、性别(enum, byte)和电话号码(ulong)。本来我想用struct表示personal_info(table)，但是struct不允许有数组或string成员，无奈我用table描述它了。相应的idl文件如下：
//////////////////////////////////////////////////////
//// FILE : tellist.fbs
//// DESC : basic message for msg-center
//// AUTHOR : v 0.1 written by Alex Stocks on June 22, 2014
//// LICENCE :
//// MOD :
////////////////////////////////////////////////////////
namespace as.tellist;
enum GENDER_TYPE : byte
{
MALE = 0,
FEMALE = 1,
OTHER = 2
}
table personal_info
{
id : uint;
name : string;
age : byte;
gender : GENDER_TYPE;
phone_num : ulong;
}
table personal_info_list
{
info : [personal_info];
}
root_type personal_info_list;
因为要以protobuf做性能参考，列出protobuf的idl文件如下：
//////////////////////////////////////////////////////
//// FILE : tellist.proto
//// DESC : basic message for msg-center
//// AUTHOR : v 0.1 written by Alex Stocks on June 22, 2014
//// LICENCE :
//// MOD :
////////////////////////////////////////////////////////
package as.tellist;
enum gender_type
{
MALE = 0;
FEMALE = 1;
OTHER = 2;
}
message personal_info
{
optional uint32 id = 1;
optional string name = 2;
optional uint32 age = 3;
optional gender_type gender = 4;
optional uint64 phone_num = 5;
}
message personal_info_list
{
repeated personal_info info = 1;
}
在内存中构造37个personal_info对象，并序列化之，重复这个过程100万次。
测试结果如下：
测试环境：12Core Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
free
total used free shared buffers cached
Mem: 66081944 65831100 250844 0 182240 46903452
-/+ buffers/cache: 18745408 47336536
Swap: 975864 724648 251216
protobuf三次测试结果：
./bin/tellist_test
loop = 1000000, time diff = 14283ms
buf size:841
bin/tellist_test
loop = 1000000, time diff = 14096ms
buf size:841
bin/tellist_test
loop = 1000000, time diff = 14229ms
buf size:841
占用内存空间841Byte，平均运算时间42608ms / 3 = 14202.7ms
flatbuffers三次测试结果：
bin/tellist_test
loop = 1000000, time diff = 11694ms
buf size:1712
bin/tellist_test
loop = 1000000, time diff = 11710ms
buf size:1712
bin/tellist_test
loop = 1000000, time diff = 11774ms
buf size:1712
占用内存空间1712Byte，平均运算时间35178ms / 3 = 11726ms
测试环境：1 Core Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
MEM
total used free shared buffers cached
Mem: 753932 432672 321260 0 89236 258052
-/+ buffers/cache: 85384 668548
Swap: 1324028 0 1324028
protobuf三次测试结果：
bin/tellist_test
loop = 1000000, time diff = 12779ms
buf size:841
bin/tellist_test
loop = 1000000, time diff = 13475ms
buf size:841
bin/tellist_test
loop = 1000000, time diff = 12604ms
buf size:841
占用内存空间841Byte，平均运算时间38858ms / 3 = 12952.7ms
flatbuffers三次测试结果：
bin/tellist_test
loop = 1000000, time diff = 9424ms
buf size:1712
bin/tellist_test
loop = 1000000, time diff = 9277ms
buf size:1712
bin/tellist_test
loop = 1000000, time diff = 9265ms
buf size:1712
info vecotor size:37, its right size:37
占用内存空间1712Byte，平均运算时间28036ms / 3 = 9345ms
从以上数据看出，在内存空间占用这个指标上，FlatBuffers占用的内存空间比protobuf多了两倍，而二者的cpu计算时间虽然相差3000ms左右，但考虑到测试用了100万次，二者每次计算时间几乎没有差别。
从以上测试数据来看，FlatBuffers的性能并不如它吹嘘的那么好，个人稍有点失望。FB大量使用了C++11的语法，其从idl生成的代码接口也不如protubuf友好。不过相比使用protobuf时的一堆头文件和占18M之多的lib库，FlatBuffers仅仅一个"flatbuffers/flatbuffers.h"就足够了。
测试程序已经上传到百度网盘，点击这个链接即可下载。欢迎各位的批评意见。
FlatBuffers与protobuf性能比较,布布扣,bubuko.com
原文地址：http://www.cnblogs.com/menggucaoyuan/p/3807546.html
