Re: bench: binary trees

From:
W Karas <wkaras@yahoo.com>
Newsgroups:
comp.lang.c++
Date:
Sat, 28 Jul 2012 16:31:01 -0700 (PDT)
Message-ID:
<afe884a4-b276-47e7-bb4a-8b18959c250c@googlegroups.com>
On Saturday, July 28, 2012 7:20:04 PM UTC-4, Melzzzzz wrote:

I have played a little tree with benchmark from computer language game
 
site:
 
http://shootout.alioth.debian.org/u64q/performance.php?test=binarytrees
 
 
 
Interested in gc vs manual I have been very surprised with Java
 
performance ;)
 
Seems that Java gc is blazingly fast in comparison with standard
 
new/delete.


Is it possible that the benchmark never causes GC to run? Is so, that woul=
d also mean any time it took to run destructors was also ignored in the Jav=
a case.

 
I think this is because gc deallocates in chunks rather piece by
 
piece, perhaps allocates from pool. Also there are no destructors
 
calls.
 
fastest C++ program on this site uses boost pool which calls
 
destructors and can deallocate, therefore, is slower then C variant
 
which uses apache's pool, which just deallocate.
 
 
 
So I have coded simple custom pool that does not keeps track of
 
allocated objects and doesn't call destructors and result is
 
that it is slightly faster than C ;)
 
 
 
What is clear is that Java garbage collector cannot be bitten
 
in this case if manual deletion of objects is required.
 
(as seen here)
 
http://shootout.alioth.debian.org/u64/performance.php?test=binarytrees
 
 
 
Timings for cpp with my custom alloc
 
bmaxa@maxa:~/shootout/trees$ time ./binarytreescpp 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m4.188s
 
user 0m7.036s
 
sys 0m0.112s
 
bmaxa@maxa:~/shootout/trees$ time taskset -c 0 ./binarytreescpp 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m7.077s
 
user 0m6.976s
 
sys 0m0.084s
 
 
 
Timings for C with apache pool:
 
bmaxa@maxa:~/shootout/trees$ time ./binarytreesc 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m4.625s
 
user 0m8.085s
 
sys 0m0.140s
 
bmaxa@maxa:~/shootout/trees$ time taskset -c 0 ./binarytreesc 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m8.009s
 
user 0m7.888s
 
sys 0m0.116s
 
 
 
code follows if someone is interested:
 
/* The Computer Language Benchmarks Game
 
 * http://shootout.alioth.debian.org/
 
 *
 
 * contributed by Jon Harrop
 
 * modified by Alex Mizrahi
 
 * modified by Andreas Sch=E4fer
 
 * very minor omp tweak by The Anh Tran
 
 * custom pool Branimir Maksimovic
 
 */
 
 
 
#include <iostream>
 
#include <stdlib.h>
 
#include <stdio.h>
 
#include <vector>
 
#include <new>
 
#include <pthread.h>
 
#include <boost/pool/object_pool.hpp>
 
 
 
const size_t LINE_SIZE = 64;
 
 
 
template <class T>
 
class Pool{
 
static const unsigned NELEM = 10000*sizeof(T);
 
public:
 
    Pool()
 
    : pos_(0)
 
    {
 
        pool_.push_back(alloc());
 
    }
 
    Pool(const Pool&)=delete;
 
    Pool& operator=(const Pool&)=delete;
 
    ~Pool()
 
    {
 
        for(auto i : pool_)
 
        {
 
            free(i);
 
        }
 
    }
 
    template <class ...T1>
 
    T* allocate(T1... args)
 
    {
 
        if(NELEM <= pos_)
 
        {
 
            pool_.push_back(alloc());
 
            pos_=0;
 
        }
 
        void* p = &pool_.back()[pos_];
 
        pos_+=sizeof(T);
 
        return new(p)T(args...);
 
    }
 
private:
 
    static char* alloc()
 
    {
 
        Inner* next = (Inner*)pthread_getspecific(k.key);
 
        if(next == nullptr)
 
        {
 
            next = (Inner*)::operator new(NELEM);
 
            next->next = nullptr;
 
        }
 
        char* p = (char*)next;
 
        next = next->next;
 
        pthread_setspecific(k.key,next);
 
        return p;
 
    }
 
    static void free(void* p)
 
    {
 
        Inner* next = (Inner*)pthread_getspecific(k.key);
 
        Inner* tmp = (Inner*)p;
 
        tmp->next = next;
 
        next = tmp;
 
        pthread_setspecific(k.key,next);
 
    }
 
    std::vector<char*> pool_;
 
    unsigned pos_;
 
    struct Inner{
 
    Inner* next;
 
    };
 
    static struct Key{
 
    Key()
 
    {
 
        pthread_key_create(&key,destroy);
 
    }
 
    ~Key()
 
    {
 
        pthread_key_delete(key);
 
    }
 
    static void destroy(void* p)
 
    {
 
        Inner* next = (Inner*)p;
 
        while(next)
 
        {
 
            Inner* tmp = next->next;
 
            ::operator delete(next);
 
            next = tmp;
 
        }
 
    }
 
    pthread_key_t key;
 
    }k;
 
};
 
 
 
template <class T>
 
typename Pool<T>::Key Pool<T>::k;
 
 
 
struct Node
 
{
 
    Node *l, *r;
 
    int i;
 
    
 
    Node(int i2) :l(0),r(0), i(i2)
 
    {}
 
    Node(Node *l2, int i2, Node *r2) : l(l2), r(r2), i(i2)
 
    {}
 
    Node(const Node&)=delete;
 
    Node& operator=(const Node&)=delete;
 
    int check() const
 
    {
 
        if (l)
 
            return l->check() + i - r->check();
 
        else return i;
 
    }
 
};
 
 
 
typedef boost::object_pool<Node> NodePool;
 
 
 
Node *make(int i, int d, Pool<Node>& p)
 
{
 
    if (d > 0)
 
        return p.allocate( make(2*i-1, d-1,p),
 
         i,
 
         make(2*i, d-1,p));
 
    return p.allocate(i);
 
}
 
 
 
Node *make(int i, int d, NodePool& p)
 
{
 
    if (d > 0)
 
        return p.construct( make(2*i-1, d-1,p),
 
         i,
 
         make(2*i, d-1,p));
 
    return p.construct(i);
 
}
 
 
 
int main(int argc, char *argv[])
 
{
 
    int min_depth = 4;
 
    int max_depth = std::max(min_depth+2,
 
                             (argc == 2 ? atoi(argv[1]) : 10));
 
    int stretch_depth = max_depth+1;
 
 
 
    // Alloc then dealloc stretchdepth tree
 
    {
 
        Pool<Node> c_pool;
 
        //NodePool c_pool;
 
        Node* c (make(0, stretch_depth,c_pool));
 
        std::cout << "stretch tree of depth " << stretch_depth << "\t "
 
                  << "check: " << c->check() << '\n';
 
    }
 
 
 
    Pool<Node> long_lived_tree_pool;
 
    //NodePool long_lived_tree_pool;
 
    Node* long_lived_tree(make(0, max_depth,long_lived_tree_pool));
 
 
 
    char *outputstr = (char*)malloc(LINE_SIZE * (max_depth +1) * sizeof=

(char));

 
    
 
    #pragma omp parallel for
 
    for (int d = min_depth; d <= max_depth; d += 2)
 
    {
 
        int iterations = 1 << (max_depth - d + min_depth);
 
        int c = 0;
 
 
 
        for (int i = 1; i <= iterations; ++i)
 
        {
 
            Pool<Node> pool;
 
            //NodePool pool;
 
            Node *a(make(i, d,pool)), *b(make(-i, d,pool));
 
            c += a->check() + b->check();
 
        }
 
 
 
        sprintf(outputstr + LINE_SIZE * d, "%d\t trees of depth %d\t check: %d\=
n", (2 * iterations), d, c);

 
    }
 
 
 
    for (int d = min_depth; d <= max_depth; d += 2)
 
        printf("%s", outputstr + (d * LINE_SIZE) );
 
    free(outputstr);
 
 
 
    std::cout << "long lived tree of depth " << max_depth << "\t "
 
              << "check: " << (long_lived_tree->check()) << '\n';
 
 
 
    return 0;
 
}


On Saturday, July 28, 2012 7:20:04 PM UTC-4, Melzzzzz wrote:

I have played a little tree with benchmark from computer language game
 
site:
 
http://shootout.alioth.debian.org/u64q/performance.php?test=binarytrees
 
 
 
Interested in gc vs manual I have been very surprised with Java
 
performance ;)
 
Seems that Java gc is blazingly fast in comparison with standard
 
new/delete.
 
I think this is because gc deallocates in chunks rather piece by
 
piece, perhaps allocates from pool. Also there are no destructors
 
calls.
 
fastest C++ program on this site uses boost pool which calls
 
destructors and can deallocate, therefore, is slower then C variant
 
which uses apache's pool, which just deallocate.
 
 
 
So I have coded simple custom pool that does not keeps track of
 
allocated objects and doesn't call destructors and result is
 
that it is slightly faster than C ;)
 
 
 
What is clear is that Java garbage collector cannot be bitten
 
in this case if manual deletion of objects is required.
 
(as seen here)
 
http://shootout.alioth.debian.org/u64/performance.php?test=binarytrees
 
 
 
Timings for cpp with my custom alloc
 
bmaxa@maxa:~/shootout/trees$ time ./binarytreescpp 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m4.188s
 
user 0m7.036s
 
sys 0m0.112s
 
bmaxa@maxa:~/shootout/trees$ time taskset -c 0 ./binarytreescpp 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m7.077s
 
user 0m6.976s
 
sys 0m0.084s
 
 
 
Timings for C with apache pool:
 
bmaxa@maxa:~/shootout/trees$ time ./binarytreesc 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m4.625s
 
user 0m8.085s
 
sys 0m0.140s
 
bmaxa@maxa:~/shootout/trees$ time taskset -c 0 ./binarytreesc 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m8.009s
 
user 0m7.888s
 
sys 0m0.116s
 
 
 
code follows if someone is interested:
 
/* The Computer Language Benchmarks Game
 
 * http://shootout.alioth.debian.org/
 
 *
 
 * contributed by Jon Harrop
 
 * modified by Alex Mizrahi
 
 * modified by Andreas Sch=E4fer
 
 * very minor omp tweak by The Anh Tran
 
 * custom pool Branimir Maksimovic
 
 */
 
 
 
#include <iostream>
 
#include <stdlib.h>
 
#include <stdio.h>
 
#include <vector>
 
#include <new>
 
#include <pthread.h>
 
#include <boost/pool/object_pool.hpp>
 
 
 
const size_t LINE_SIZE = 64;
 
 
 
template <class T>
 
class Pool{
 
static const unsigned NELEM = 10000*sizeof(T);
 
public:
 
    Pool()
 
    : pos_(0)
 
    {
 
        pool_.push_back(alloc());
 
    }
 
    Pool(const Pool&)=delete;
 
    Pool& operator=(const Pool&)=delete;
 
    ~Pool()
 
    {
 
        for(auto i : pool_)
 
        {
 
            free(i);
 
        }
 
    }
 
    template <class ...T1>
 
    T* allocate(T1... args)
 
    {
 
        if(NELEM <= pos_)
 
        {
 
            pool_.push_back(alloc());
 
            pos_=0;
 
        }
 
        void* p = &pool_.back()[pos_];
 
        pos_+=sizeof(T);
 
        return new(p)T(args...);
 
    }
 
private:
 
    static char* alloc()
 
    {
 
        Inner* next = (Inner*)pthread_getspecific(k.key);
 
        if(next == nullptr)
 
        {
 
            next = (Inner*)::operator new(NELEM);
 
            next->next = nullptr;
 
        }
 
        char* p = (char*)next;
 
        next = next->next;
 
        pthread_setspecific(k.key,next);
 
        return p;
 
    }
 
    static void free(void* p)
 
    {
 
        Inner* next = (Inner*)pthread_getspecific(k.key);
 
        Inner* tmp = (Inner*)p;
 
        tmp->next = next;
 
        next = tmp;
 
        pthread_setspecific(k.key,next);
 
    }
 
    std::vector<char*> pool_;
 
    unsigned pos_;
 
    struct Inner{
 
    Inner* next;
 
    };
 
    static struct Key{
 
    Key()
 
    {
 
        pthread_key_create(&key,destroy);
 
    }
 
    ~Key()
 
    {
 
        pthread_key_delete(key);
 
    }
 
    static void destroy(void* p)
 
    {
 
        Inner* next = (Inner*)p;
 
        while(next)
 
        {
 
            Inner* tmp = next->next;
 
            ::operator delete(next);
 
            next = tmp;
 
        }
 
    }
 
    pthread_key_t key;
 
    }k;
 
};
 
 
 
template <class T>
 
typename Pool<T>::Key Pool<T>::k;
 
 
 
struct Node
 
{
 
    Node *l, *r;
 
    int i;
 
    
 
    Node(int i2) :l(0),r(0), i(i2)
 
    {}
 
    Node(Node *l2, int i2, Node *r2) : l(l2), r(r2), i(i2)
 
    {}
 
    Node(const Node&)=delete;
 
    Node& operator=(const Node&)=delete;
 
    int check() const
 
    {
 
        if (l)
 
            return l->check() + i - r->check();
 
        else return i;
 
    }
 
};
 
 
 
typedef boost::object_pool<Node> NodePool;
 
 
 
Node *make(int i, int d, Pool<Node>& p)
 
{
 
    if (d > 0)
 
        return p.allocate( make(2*i-1, d-1,p),
 
         i,
 
         make(2*i, d-1,p));
 
    return p.allocate(i);
 
}
 
 
 
Node *make(int i, int d, NodePool& p)
 
{
 
    if (d > 0)
 
        return p.construct( make(2*i-1, d-1,p),
 
         i,
 
         make(2*i, d-1,p));
 
    return p.construct(i);
 
}
 
 
 
int main(int argc, char *argv[])
 
{
 
    int min_depth = 4;
 
    int max_depth = std::max(min_depth+2,
 
                             (argc == 2 ? atoi(argv[1]) : 10));
 
    int stretch_depth = max_depth+1;
 
 
 
    // Alloc then dealloc stretchdepth tree
 
    {
 
        Pool<Node> c_pool;
 
        //NodePool c_pool;
 
        Node* c (make(0, stretch_depth,c_pool));
 
        std::cout << "stretch tree of depth " << stretch_depth << "\t "
 
                  << "check: " << c->check() << '\n';
 
    }
 
 
 
    Pool<Node> long_lived_tree_pool;
 
    //NodePool long_lived_tree_pool;
 
    Node* long_lived_tree(make(0, max_depth,long_lived_tree_pool));
 
 
 
    char *outputstr = (char*)malloc(LINE_SIZE * (max_depth +1) * sizeof=

(char));

 
    
 
    #pragma omp parallel for
 
    for (int d = min_depth; d <= max_depth; d += 2)
 
    {
 
        int iterations = 1 << (max_depth - d + min_depth);
 
        int c = 0;
 
 
 
        for (int i = 1; i <= iterations; ++i)
 
        {
 
            Pool<Node> pool;
 
            //NodePool pool;
 
            Node *a(make(i, d,pool)), *b(make(-i, d,pool));
 
            c += a->check() + b->check();
 
        }
 
 
 
        sprintf(outputstr + LINE_SIZE * d, "%d\t trees of depth %d\t check: %d\=
n", (2 * iterations), d, c);

 
    }
 
 
 
    for (int d = min_depth; d <= max_depth; d += 2)
 
        printf("%s", outputstr + (d * LINE_SIZE) );
 
    free(outputstr);
 
 
 
    std::cout << "long lived tree of depth " << max_depth << "\t "
 
              << "check: " << (long_lived_tree->check()) << '\n';
 
 
 
    return 0;
 
}


On Saturday, July 28, 2012 7:20:04 PM UTC-4, Melzzzzz wrote:

I have played a little tree with benchmark from computer language game
 
site:
 
http://shootout.alioth.debian.org/u64q/performance.php?test=binarytrees
 
 
 
Interested in gc vs manual I have been very surprised with Java
 
performance ;)
 
Seems that Java gc is blazingly fast in comparison with standard
 
new/delete.
 
I think this is because gc deallocates in chunks rather piece by
 
piece, perhaps allocates from pool. Also there are no destructors
 
calls.
 
fastest C++ program on this site uses boost pool which calls
 
destructors and can deallocate, therefore, is slower then C variant
 
which uses apache's pool, which just deallocate.
 
 
 
So I have coded simple custom pool that does not keeps track of
 
allocated objects and doesn't call destructors and result is
 
that it is slightly faster than C ;)
 
 
 
What is clear is that Java garbage collector cannot be bitten
 
in this case if manual deletion of objects is required.
 
(as seen here)
 
http://shootout.alioth.debian.org/u64/performance.php?test=binarytrees
 
 
 
Timings for cpp with my custom alloc
 
bmaxa@maxa:~/shootout/trees$ time ./binarytreescpp 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m4.188s
 
user 0m7.036s
 
sys 0m0.112s
 
bmaxa@maxa:~/shootout/trees$ time taskset -c 0 ./binarytreescpp 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m7.077s
 
user 0m6.976s
 
sys 0m0.084s
 
 
 
Timings for C with apache pool:
 
bmaxa@maxa:~/shootout/trees$ time ./binarytreesc 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m4.625s
 
user 0m8.085s
 
sys 0m0.140s
 
bmaxa@maxa:~/shootout/trees$ time taskset -c 0 ./binarytreesc 20
 
stretch tree of depth 21 check: -1
 
2097152 trees of depth 4 check: -2097152
 
524288 trees of depth 6 check: -524288
 
131072 trees of depth 8 check: -131072
 
32768 trees of depth 10 check: -32768
 
8192 trees of depth 12 check: -8192
 
2048 trees of depth 14 check: -2048
 
512 trees of depth 16 check: -512
 
128 trees of depth 18 check: -128
 
32 trees of depth 20 check: -32
 
long lived tree of depth 20 check: -1
 
 
 
real 0m8.009s
 
user 0m7.888s
 
sys 0m0.116s
 
 
 
code follows if someone is interested:
 
/* The Computer Language Benchmarks Game
 
 * http://shootout.alioth.debian.org/
 
 *
 
 * contributed by Jon Harrop
 
 * modified by Alex Mizrahi
 
 * modified by Andreas Sch=E4fer
 
 * very minor omp tweak by The Anh Tran
 
 * custom pool Branimir Maksimovic
 
 */
 
 
 
#include <iostream>
 
#include <stdlib.h>
 
#include <stdio.h>
 
#include <vector>
 
#include <new>
 
#include <pthread.h>
 
#include <boost/pool/object_pool.hpp>
 
 
 
const size_t LINE_SIZE = 64;
 
 
 
template <class T>
 
class Pool{
 
static const unsigned NELEM = 10000*sizeof(T);
 
public:
 
    Pool()
 
    : pos_(0)
 
    {
 
        pool_.push_back(alloc());
 
    }
 
    Pool(const Pool&)=delete;
 
    Pool& operator=(const Pool&)=delete;
 
    ~Pool()
 
    {
 
        for(auto i : pool_)
 
        {
 
            free(i);
 
        }
 
    }
 
    template <class ...T1>
 
    T* allocate(T1... args)
 
    {
 
        if(NELEM <= pos_)
 
        {
 
            pool_.push_back(alloc());
 
            pos_=0;
 
        }
 
        void* p = &pool_.back()[pos_];
 
        pos_+=sizeof(T);
 
        return new(p)T(args...);
 
    }
 
private:
 
    static char* alloc()
 
    {
 
        Inner* next = (Inner*)pthread_getspecific(k.key);
 
        if(next == nullptr)
 
        {
 
            next = (Inner*)::operator new(NELEM);
 
            next->next = nullptr;
 
        }
 
        char* p = (char*)next;
 
        next = next->next;
 
        pthread_setspecific(k.key,next);
 
        return p;
 
    }
 
    static void free(void* p)
 
    {
 
        Inner* next = (Inner*)pthread_getspecific(k.key);
 
        Inner* tmp = (Inner*)p;
 
        tmp->next = next;
 
        next = tmp;
 
        pthread_setspecific(k.key,next);
 
    }
 
    std::vector<char*> pool_;
 
    unsigned pos_;
 
    struct Inner{
 
    Inner* next;
 
    };
 
    static struct Key{
 
    Key()
 
    {
 
        pthread_key_create(&key,destroy);
 
    }
 
    ~Key()
 
    {
 
        pthread_key_delete(key);
 
    }
 
    static void destroy(void* p)
 
    {
 
        Inner* next = (Inner*)p;
 
        while(next)
 
        {
 
            Inner* tmp = next->next;
 
            ::operator delete(next);
 
            next = tmp;
 
        }
 
    }
 
    pthread_key_t key;
 
    }k;
 
};
 
 
 
template <class T>
 
typename Pool<T>::Key Pool<T>::k;
 
 
 
struct Node
 
{
 
    Node *l, *r;
 
    int i;
 
    
 
    Node(int i2) :l(0),r(0), i(i2)
 
    {}
 
    Node(Node *l2, int i2, Node *r2) : l(l2), r(r2), i(i2)
 
    {}
 
    Node(const Node&)=delete;
 
    Node& operator=(const Node&)=delete;
 
    int check() const
 
    {
 
        if (l)
 
            return l->check() + i - r->check();
 
        else return i;
 
    }
 
};
 
 
 
typedef boost::object_pool<Node> NodePool;
 
 
 
Node *make(int i, int d, Pool<Node>& p)
 
{
 
    if (d > 0)
 
        return p.allocate( make(2*i-1, d-1,p),
 
         i,
 
         make(2*i, d-1,p));
 
    return p.allocate(i);
 
}
 
 
 
Node *make(int i, int d, NodePool& p)
 
{
 
    if (d > 0)
 
        return p.construct( make(2*i-1, d-1,p),
 
         i,
 
         make(2*i, d-1,p));
 
    return p.construct(i);
 
}
 
 
 
int main(int argc, char *argv[])
 
{
 
    int min_depth = 4;
 
    int max_depth = std::max(min_depth+2,
 
                             (argc == 2 ? atoi(argv[1]) : 10));
 
    int stretch_depth = max_depth+1;
 
 
 
    // Alloc then dealloc stretchdepth tree
 
    {
 
        Pool<Node> c_pool;
 
        //NodePool c_pool;
 
        Node* c (make(0, stretch_depth,c_pool));
 
        std::cout << "stretch tree of depth " << stretch_depth << "\t "
 
                  << "check: " << c->check() << '\n';
 
    }
 
 
 
    Pool<Node> long_lived_tree_pool;
 
    //NodePool long_lived_tree_pool;
 
    Node* long_lived_tree(make(0, max_depth,long_lived_tree_pool));
 
 
 
    char *outputstr = (char*)malloc(LINE_SIZE * (max_depth +1) * sizeof=

(char));

 
    
 
    #pragma omp parallel for
 
    for (int d = min_depth; d <= max_depth; d += 2)
 
    {
 
        int iterations = 1 << (max_depth - d + min_depth);
 
        int c = 0;
 
 
 
        for (int i = 1; i <= iterations; ++i)
 
        {
 
            Pool<Node> pool;
 
            //NodePool pool;
 
            Node *a(make(i, d,pool)), *b(make(-i, d,pool));
 
            c += a->check() + b->check();
 
        }
 
 
 
        sprintf(outputstr + LINE_SIZE * d, "%d\t trees of depth %d\t check: %d\=
n", (2 * iterations), d, c);

 
    }
 
 
 
    for (int d = min_depth; d <= max_depth; d += 2)
 
        printf("%s", outputstr + (d * LINE_SIZE) );
 
    free(outputstr);
 
 
 
    std::cout << "long lived tree of depth " << max_depth << "\t "
 
              << "check: " << (long_lived_tree->check()) << '\n';
 
 
 
    return 0;
 
}

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