Fastest way to clone a hash_map

Hi,

I have the need to take a snapshot of a hash_map during execution
(actually transform it to a vector).  This map is a shared resource
and therefore must be locked prior to any read/write operations thus I
need to minimize the amount of time the map resource is locked.

The map is defined as type <string, boost::shared_ptr<myobject>>.  My
algorithm is as such:

void SnapShotToVector( vector< pair< string,
boost::shared_ptr<myobject> >& vec )
{

    lockResource(this->map);
    vec.resize( map.size() );
    copy(this->map.begin(), this->map.end(),list.begin());
    unlockResource(this->map);
}

For about 3M elements w/in the map, I'm noticing that the resize op
takes about 150ms and the copy takes ~850ms.  Is there any way to do
better? I suppose the total time doesn' t matter as it's the time the
resource is actually locked is the primary concern.

TIA

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