Re: why boost:shared_ptr so slower?

Maxim Yegorushkin <>
Thu, 20 Aug 2009 15:01:10 +0100
chris wrote:

I've just done a performance test on the shared_ptr compared to the
native pointer case, the results show at lease 3 times slower when the
iteration number > 10000, this is the code snippet:

#include <vector>
#include <iostream>
#include <boost/shared_ptr.hpp>

using namespace std;
using namespace boost;

class Thing

 void method (void)
   int i = 5;

typedef boost::shared_ptr<Thing> ThingPtr;

void processThing(Thing* thing)

//loop1 and loop2 test shared_ptr in the vector container
void loop1(long long num)
 vector<ThingPtr> thingPtrs;

 for(int i=0; i< num; i++) {
   ThingPtr p1(new Thing);

loop1 one body does up to three memory allocations: one in 'new Thing', another
in 'ThingPtr p(<raw-pointer>)' and the last one in vector::push_back().

void loop2(long long num)
 vector<Thing> thingPtrs;
 for(int i=0; i< num; i++) {
   Thing thing;

loop2 does at most one memory allocation in vector::push_back() and a copy of
thing. So, given that Thing small, loop2 always wins.

//loop3 and loop4 test shared_ptr in the vector container
void loop3(long long num)
 for(int i=0; i< num; i++) {
   ThingPtr p1(new Thing);

void loop4(long long num)
 for(int i=0; i< num; i++) {
   Thing* p1 = new Thing();
   delete p1;

The results are the following:
CPU: Intel Core2 Quad CPU Q8200
OS: Windows XP SP2
Compiler: Visual Studio 2005

loop1 vs loop2: 100000 times
loop1 elapsed 390 msec
loop2 elapsed 93 msec

loop5 vs loop6: 100000 times
loop5 elapsed 171 msec
loop6 elapsed 78 msec

Well, you posted results of loop1 vs loop2 which compare quite different things
and loop5 vs. loop6, for which you did not provide any source code. Your
question can not be answered, since there are no relevant facts provided.


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