Re: Smart strings & memory allocation

SS>> Common referred to real applications, not 'make test'. Do you have some data about real applications in PHP that use strings longer than 80 bytes via smart strings? My tests show most of the strings used are small. Looking at the clients of this functions and taking into account that prontf's are usually small and long printf are usually or rewritten into heredocs (which don't use smart strings) or separated into different functions. BTW, why do you think "make test" is a bad test of memory allocation patterns? What do you propose as a better test? SS>> In fact, whenever strings are not allocated through the SS>> engine, 80 bytes is a really poor choice, because the malloc SS>> implementation will very likely allocate a 128 byte chunk SS>> anyway. That's very bad news, because actually my test show that about 95% of mallocs are for sizes below 100 bytes. But I hope the system malloc has some mechanism to deal with it, otherwise we are wasting a real lot of memory. Actually, given that tests show 90% of mallocs are for sizes below 64 bytes, if what you say is right, PHP's memory footprint is at least twice as big as it is meant to be. The number 80 was chosen because even if malloc allocates 128 bytes, these 128 bytes would be reused using the Zend memory cache. However, if the size of the segment does not allow it to be into the Zend memory cache, new malloc would be attempted each time. That was the primery rationale for the change, not the memory-saving argument, though it is important too. BTW, the number 128 in the code allocated in fact at least 148 bytes, and I don't know what malloc implemetation would do of this. -- Stanislav Malyshev, Zend Products Engineer stas@zend.com http://www.zend.com/ +972-3-6139665 ext.109