TBB Concurrent Hash map

Question

I am implementing tbb's concurrent hash map to compare the performance of it against a suite of other concurrent hash tables.

However the performance I get out of it is horrendous, I just can't believe it is that slow compared to other concurrent hash tables

Here is my implementation of it:

class TBB: public TestDs{
    typedef tbb::concurrent_hash_map<int,int, HashCompare<int> > hash_t;
private:
        hash_t _ds;
public:
        TBB(const Configuration& config) : _ds(config.initial_count) {
        }

    bool containsKey(int key) {
        hash_t::accessor a;

        if(_ds.find(a,key)){
            return true;
        }
        else 
            return false;
    }

    int get(int key) {
        hash_t::accessor a;

        if(_ds.find(a,key)){
             return (int)(a->second);
        }
        else 
            return 0;
    }

    int put(int key, int value) {
        return _ds.insert( std::make_pair(key, value) );
    }

    int remove(int key) {
        return _ds.erase(key);
    }

    int size() {
        return _ds.size();
    }
    const char* name() {
        return "TBB";
    }
    void print() {}
    void shutdown() {}

};

Does anyone see any issue with my implementation or know of any reason why it may perform slow? It takes over 30 mins for it to insert 200,000 elements in a single thread environment. To put that in perspective, nearly all the other tables perform this test in less than 5 mins.

Here is my build code:

-w  -DNDEBUG -g -msse2 -m32  -DINTEL -D_REENTRANT -lrt -pthread -fno-strict-aliasing -l cds -l tbb -lllalloc 

UPDATE: I have adjusted my testing code to prefill the hash tables to 1000, instead of 100,000. When running it again, tbb performs 92 op/sec while, another implementation performs 89431 op/sec. (64 thread environment)...Just saying something doesn't seem right....

Additional Info: Computer is a HP Z600 Workstation with 6gb of ram and 6 cores.

Notice Cross positing at : http://software.intel.com/en-us/forums/showthread.php?t=86119

Answer 1

You HashCompare::hash() returns sizeof(int), which, I guess, means every entry maps into the same bucket. It seems like you are not using it as a hash table, more of a linked list.

You could try using Boost's hash:

#include <boost/functional/hash.hpp>

template<typename K> 
struct HashCompare { 
    static size_t hash( const K& key )                  { return boost::hash_value(key); } 
    static bool   equal( const K& key1, const K& key2 ) { return ( key1 == key2 ); } 
};