Object pool is very slow. destroy() is O(n) where n is the number of free objects. Therefore if you allocate N objects and then destroy N objects, you end up with a O(N^2) runtime. LET ME SAY THAT AGAIN: ObjectPool is O(n^2) FOR THE TYPICAL USAGE OF A POOL!!! The ( bad IMHO ) reason for doing this is in order to keep the free list sorted so that ~ObjectPool() runs in O(n) instead of O(n^2). However, if it wanted to ~ObjectPool() could just sort the free list in O(n logn) so there is no need at all for destroy() to keep it sorted. However, my personal feelings about a pool is that the pool should not be calling the destructors on any objects that are still allocated when the pool is destroyed. I know that standard containers will call distructors, but a pools are NOT a container. The usage of a pool is closer to the new and delete operator. If you 'new' an object, and then do an exit(), your object does not get deleted before the process is destroyed. Why should a pool work any differently? If you want to create a bunch of objects and then destroy them all at once, then use a container. If you have any allocated objects still around when a pool is destroyed, It is a bug unless the process is about to exit. I thought about submitting a patch, but I don't think there is anyone who is maintaining boost::pool. The workaround to make object pool fast is just to modify object pool header to use free() instead of orderedFree() and then modify the destructor to not call the destructors of the objects that are still allocated. On Wed, Mar 11, 2009 at 11:42 PM, Qiu Yuzhou <qbowater@gmail.com> wrote:
Hi,
Lock is slow. The pool lib is for performance.
2009/3/12 <jon_zhou@agilent.com>:
hi
seems only singleton_pool is thread-safe? but it just only alloc memory and does not call ctor...
why object_pool is not designed as thread-safe? Just like the stl container vector,list... are not thread-safe. The user should lock his mutex by himself if it's in need.
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