ID: 40165
User updated by: gacek at intertele dot pl
Reported By: gacek at intertele dot pl
-Status: Bogus
+Status: Open
Bug Type: Performance problem
Operating System: Linux FC4 x86_64
PHP Version: 5.2.0
New Comment:
OK, comparison with count() was probably bad, but I will give you
another example:
I have declared 3 functions named myf1, myf2, myf3, which play with
hash table. Not big one (10-20 elements), but processing is a bit
complex. apd profiler shows following call tree of myf1():
myf1
func_num_args
func_num_args
func_get_args
myf2
count
array_shift
is_array
reset
each
each
each
count
array_shift
array_shift
is_array
reset
each
in_array
each
in_array
each
count
array_shift
is_array
array_shift
count
array_shift
is_array
array_shift
count
myf3
each
is_array
each
is_array
each
is_array
each
is_array
count
urlencode
array_push
count
urlencode
array_push
count
reset
ksort
each
is_array
ereg_replace
ereg_replace
ereg_replace
ereg_replace
urlencode
urlencode
array_push
each
join
Each call of myf1() does nearly the same and operates on similiar hash.
As you can see, above code envolves really complex operations as
urlenconde'ing and ereg_replace'ing.
Now, let's take a look at sample "pprofp -U" output. I have taken only
relevant rows from it:
Total Elapsed Time = 0.40
Total System Time = 0.04
Total User Time = 0.35
Real User System secs/ cumm
%Time (excl/cumm) (excl/cumm) (excl/cumm) Calls call s/call
Memory Usage Name
--------------------------------------------------------------------------------------
100.0 0.00 0.40 0.00 0.35 0.00 0.04 1 0.0000 0.3480
0 main
56.3 0.22 0.22 0.20 0.20 0.03 0.03 850 0.0002 0.0002
0 define
5.7 0.00 0.03 0.00 0.02 0.00 0.00 43 0.0000 0.0005 0
myf1
3.4 0.00 0.02 0.00 0.01 0.00 0.00 44 0.0000 0.0003 0
myf2
2.3 0.00 0.00 0.00 0.01 0.00 0.00 44 0.0000 0.0002 0
myf3
So, 850 calls of define() took cumulative 0.20s of user time from
overall 0.35s (57%). 44 calls of complex myf1() took cumulatve 0.02s of
user time (5.7%).
It looks like average constant definition takes near half of operations
from myf1() complex call tree 8-/.
I would really classify "define" as too expensive.
Previous Comments:
------------------------------------------------------------------------
[2007-01-19 14:19:12] [EMAIL PROTECTED]
count(array()) just returns ht->nNumOfElements, this is probably the
most simple function in PHP.
define() copies (malloc() + memcpy()) the value, duplicates the name
(malloc() + memcpy() again) and adds it to the hash of constants (which
might involve realloc() etc.).
So it's kinda expected that a function which does almost nothing is a
bit faster, like 7x or 6x, which are the numbers I can see myself.
------------------------------------------------------------------------
[2007-01-19 11:33:51] [EMAIL PROTECTED]
Not enough information was provided for us to be able
to handle this bug. Please re-read the instructions at
http://bugs.php.net/how-to-report.php
If you can provide more information, feel free to add it
to this bug and change the status back to "Open".
Thank you for your interest in PHP.
------------------------------------------------------------------------
[2007-01-19 11:33:22] gacek at intertele dot pl
This is sample of "pprofp -u" output from fairly complex app:
Total Elapsed Time = 2.47
Total System Time = 0.35
Total User Time = 1.36
Real User System secs/ cumm
%Time (excl/cumm) (excl/cumm) (excl/cumm) Calls call s/call
Memory Usage Name
--------------------------------------------------------------------------------------
13.9 0.24 0.24 0.19 0.19 0.04 0.04 850 0.0002 0.0002
0 define
12.1 0.27 0.27 0.16 0.16 0.05 0.05 18653 0.0000 0.0000
0 count
10.9 0.15 0.15 0.15 0.15 0.04 0.04 11652 0.0000 0.0000
0 is_array
9.1 0.26 0.26 0.12 0.12 0.03 0.03 15489 0.0000 0.0000
0 each
6.2 0.18 0.18 0.08 0.08 0.02 0.02 9012 0.0000 0.0000 0
array_shift
4.1 0.08 0.08 0.06 0.06 0.02 0.02 5402 0.0000 0.0000 0
ereg_replace
4.1 0.04 0.04 0.06 0.06 0.01 0.01 655 0.0001 0.0001 0
mysql_fetch_array
3.8 0.07 0.07 0.05 0.05 0.01 0.01 5277 0.0000 0.0000 0
urlencode
2.9 0.04 0.04 0.04 0.04 0.00 0.00 2520 0.0000 0.0000 0
func_num_args
2.9 0.05 0.05 0.04 0.04 0.00 0.00 1465 0.0000 0.0000 0
sprintf
------------------------------------------------------------------------
[2007-01-19 11:28:44] gacek at intertele dot pl
Description:
------------
When playing with apd profiler, I have noticed huge cost of define()
call. It's over 20x the cost of average count() call.
Might it be apd inaccuracy or define() specifics, or define()
implementation is heavily broken?
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