Re: PHP & Memory Allocation (checked via TOP)

$str is 10 bytes then you repeat it 2000000 times That gives you 20000000 bytes. That's 20M not 10M -Rasmus Cabbar Duzayak wrote: > Hi, > > I have written a simple test program to see how php allocates memory. > Test code allocates ~10 Meg of RAM in an array within a loop till it > runs out of memory as: > > $str = rand(65, 95) . rand(65, 95) . rand(65, 95) . rand(65, 95) . > rand(65, 95); > $aa[] = str_repeat($str, 2000000); > > What I don't understand here is, for every 10 Meg memory it allocates, > mem usage goes up about 19 Megs when I look at this via top. > Basically, it allocates from physical memory in the beginning, starts > using swap when it is out of RES/Physical memory, which makes me > assume that garbage collection should kick in for temporary string > creations, and each new allocation increases the allocated memory size > by 19 Megs. > > Any idea why this is happening, and why do you think memory allocation > is so expensive in PHP? > > Thanks.. > > > Results of TOP: > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 21843 apache 17 0 19292 5232 3832 S 0.0 0.5 0:00.04 php > 21843 apache 16 0 38824 24m 3908 S 0.0 2.4 0:00.10 php > 21843 apache 15 0 58356 43m 3912 S 0.0 4.3 0:00.17 php > 21843 apache 16 0 77888 62m 3912 S 0.0 6.2 0:00.22 php > 21843 apache 15 0 97420 81m 3912 S 0.0 8.1 0:00.29 php > 21843 apache 15 0 114m 100m 3912 S 0.0 9.9 0:00.35 php > > > Results of free -m: > > total used free shared buffers cached > Mem: 1011 138 872 0 2 58 > Swap: 2008 388 1619 > > Mem: 1011 158 852 0 2 58 > Swap: 2008 388 1619 > > Mem: 1011 177 833 0 2 58 > Swap: 2008 388 1619 > > Mem: 1011 196 814 0 2 58 > Swap: 2008 388 1619 > > Mem: 1011 216 795 0 2 58 > Swap: 2008 388 1619 > > Mem: 1011 234 776 0 2 58 > Swap: 2008 388 1619 >