At 04:57 PM 6/8/2002 -0700, Brian Pane wrote: >Zeev Suraski wrote: > >>At 12:55 AM 6/9/2002, Brian Pane wrote: >> >>>I just looked through zend_alloc.c. It looks like the HeapCreate only >>>happens once, at startup--did I get that right? >> >> >>It's called on the per-thread startup (start_memory_manager(), which is >>called from alloc_globals_ctor(), which is the per-thread allocation >>'constructor'). >> >>> For PHP processing, do >>>you need a memory heap that is created at startup and used by all requests, >>>or is it sufficient to create and destroy a private heap for each request? >> >> >>We can go either way, but won't allocating and freeing these heaps >>increase fragmentation? Remember that PHP functions will also allocate >>memory outside these heaps (in 3rd party libraries). > > >In the httpd, we've done two things to minimize the fragmentation: > * Memory for these heaps is almost always allocated in chunks of > a fixed size, 8KB. > * There's a two-layer structure to the heaps: > - apr_pool objects are what the application uses. Each pool > provides a fast alloc interface, no free function, and a > "destructor" that returns all the allocated space when the > pool is destroyed. > - apr_allocator objects provide blocks of memory for the > apr_pools to use. Each apr_allocator maintains a free > list of blocks. When a pool is destroyed, its space is > returned to the apr_allocator from which it was created. > The next time we create a pool from that apr_allocator, > we can take an 8KB block from that allocator's free list > rather than interacting with the system heap.
It sounds to me as if we're going to have to write a new allocator with the same semantics as the Win32 API one. I don't think any of these two allocators would suit us very well. Andi -- PHP Development Mailing List <http://www.php.net/> To unsubscribe, visit: http://www.php.net/unsub.php
