Re: [PHP-DEV] lstat call on each directory level
Arvids Godjuks wrote:
Yesterday I made some tests on my site with strace to see how much lstat
I have and how can I optimize them. Well, I managed to get rid of them
almost at all, but now I have some questions about include_path and
including files based on current dir.
I have such structire of files
/home/file/www (that's my site root dir)
include/
- bittorrent
- global.php
lang/
- eng.lang
- rus.lang
index.php
My files are
index.php ---
require './include/bittorrent.php';
--- common.php ---
require './include/global.php';
require './lang/eng.lang';
And some other files from include dir
Default include path is ".:/usr/share/php5:/usr/share/php" and if I
don't change it it results in a bunch of lstat. Here is the trace
http://pastebin.com/m37704b6a
The thing I don't understand from trace is WHY it tests include path
BEFORE the ./ ? Why it doesn't try to load file based on relative path
first (it should hit it on first try) and then use include path?
Ok, I make in bittorrent.php - set_include_path('/home/file/www');
The only lstat i have now is
lstat("/home", {st_mode=S_IFDIR|0755, st_size=144, ...}) = 0
lstat("/home/file", {st_mode=S_IFDIR|0755, st_size=1112, ...}) = 0
lstat("/home/file/www", {st_mode=S_IFDIR|0755, st_size=11880, ...}) = 0
lstat("/home/file/www/bittorrent.php", 0x7fff8d95cca0) = -1 ENOENT (No
such file or directory)
open("/home/file/www/bittorrent.php", O_RDONLY) = -1 ENOENT (No such
file or directory)
open("/home/file/www/include/bittorrent.php", O_RDONLY) = 14
So the question is - why are they happen at all, if I include
bittorrent.php as require './include/bittorrent.php' in index.php. As i
understand it should hit the right folder from first time. Could you,
please, explain how all this works, because as it turned out it is not
so obvious as it should be...
I have PHP 5.2.6 (Gentoo Linux package name is dev-php5/php-5.2.6-r2)
and lighttpd 1.5
You missed something. You have an include 'bittorrent.php' in there
somewhere. This thread would really be more appropriate on php-users at
this point.
-Rasmus
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Re: [PHP-DEV] lstat call on each directory level
Yesterday I made some tests on my site with strace to see how much lstat I
have and how can I optimize them. Well, I managed to get rid of them almost
at all, but now I have some questions about include_path and including files
based on current dir.
I have such structire of files
/home/file/www (that's my site root dir)
include/
- bittorrent
- global.php
lang/
- eng.lang
- rus.lang
index.php
My files are
index.php ---
require './include/bittorrent.php';
--- common.php ---
require './include/global.php';
require './lang/eng.lang';
And some other files from include dir
Default include path is ".:/usr/share/php5:/usr/share/php" and if I don't
change it it results in a bunch of lstat. Here is the trace
http://pastebin.com/m37704b6a
The thing I don't understand from trace is WHY it tests include path BEFORE
the ./ ? Why it doesn't try to load file based on relative path first (it
should hit it on first try) and then use include path?
Ok, I make in bittorrent.php - set_include_path('/home/file/www');
The only lstat i have now is
lstat("/home", {st_mode=S_IFDIR|0755, st_size=144, ...}) = 0
lstat("/home/file", {st_mode=S_IFDIR|0755, st_size=1112, ...}) = 0
lstat("/home/file/www", {st_mode=S_IFDIR|0755, st_size=11880, ...}) = 0
lstat("/home/file/www/bittorrent.php", 0x7fff8d95cca0) = -1 ENOENT (No such
file or directory)
open("/home/file/www/bittorrent.php", O_RDONLY) = -1 ENOENT (No such file or
directory)
open("/home/file/www/include/bittorrent.php", O_RDONLY) = 14
So the question is - why are they happen at all, if I include bittorrent.php
as require './include/bittorrent.php' in index.php. As i understand it
should hit the right folder from first time. Could you, please, explain how
all this works, because as it turned out it is not so obvious as it should
be...
I have PHP 5.2.6 (Gentoo Linux package name is dev-php5/php-5.2.6-r2) and
lighttpd 1.5
Re: [PHP-DEV] lstat call on each directory level
Amir Hardon wrote: On Wed, 2008-07-16 at 06:45 -0700, Rasmus Lerdorf wrote: Arvids Godjuks wrote: > Hello. > > I think this should be optimized. > I'm not an expert ofcourse, but as I understood there is only one case > witch need a special treatment - require/include _one when a file with > equal contents is included from different directories. > You can make a switch witch controls if lstat is made or not in these > cases. People who know what they are doing will switch it to off and > make sure their includes don't result in Fatal error (anyway, to my > opinion it is bad desing if such thing happens). > Ofcourse open_basedir users will don't have any benefit from it, but > that's their choise. > So I think you should think it out and make this optimization to 5.3 > release. It would be great optimization, IMHO. But all these lstats should be getting cached, so I don't see how it would affect performance very much. If you are blowing your realpath cache, you need to take a look at why that is happening. We probably should disconnect clearstatcache() from the realpath_cache, and we could perhaps look at doing partial path caches through our own realpath implementation. The other thing that can suck is when you have an include_path miss. We don't cache misses like this, so if you are relying on include_path to find your files and you don't hit it on the first try, you are going to see a bunch of stats. But that is again something that is easily fixed by not writing crappy code. I think that breaking code that looks like this: require_once './a.inc'; require_once 'a.inc'; require_once '../a.inc'; require_once 'includes/a.inc'; when these all refer to the same a.inc file depending on where the parent file is and what the coder had for breakfast that morning would be a very bad idea. -Rasmus Since the realpath cache is only relevant for a single request(right?), removing these lstats calls will a major benefit. No, of course not. It would be a useless cache if that was the case. The cache spans requests. Before moving our portal dir to the / dir, ~40% of our page requests were slow on the server side (I'm not sure if my company policies allow me to expose exactly what is considered slow), after moving it ~20% of the page requests were slow! this is significant. And there are still many lstat calls made inside our portal's directory tree. Yes, you need to figure out why you are not hitting the cache, or why you are seeing so many lstat calls. There are 3 main possibilities: 1. You have a crapload of files and they simply won't fit in the cache. Increase your realpath_cache size to address this. 2. Something somewhere is calling clearstatcache() often. Don't do that. 3. You are relying on include_path to find your files and you are always missing the file on the first couple of tries. Hint, it is a good idea to get rid of "." from the beginning of your include_path and always use "./foo.inc" to include something from the current directory instead of having include_path do this for you. That lets you put some other path first in the include_path and you can then include "path/file.inc" and have that be relative to the first path in your include_path. And make sure all your include_path includes are relative to that first path. Never include something that will hit the second component of include_path. -Rasmus -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
On Wed, 2008-07-16 at 06:45 -0700, Rasmus Lerdorf wrote: > Arvids Godjuks wrote: > > Hello. > > > > I think this should be optimized. > > I'm not an expert ofcourse, but as I understood there is only one case > > witch need a special treatment - require/include _one when a file with > > equal contents is included from different directories. > > You can make a switch witch controls if lstat is made or not in these > > cases. People who know what they are doing will switch it to off and > > make sure their includes don't result in Fatal error (anyway, to my > > opinion it is bad desing if such thing happens). > > Ofcourse open_basedir users will don't have any benefit from it, but > > that's their choise. > > So I think you should think it out and make this optimization to 5.3 > > release. It would be great optimization, IMHO. > > But all these lstats should be getting cached, so I don't see how it > would affect performance very much. If you are blowing your realpath > cache, you need to take a look at why that is happening. > > We probably should disconnect clearstatcache() from the realpath_cache, > and we could perhaps look at doing partial path caches through our own > realpath implementation. The other thing that can suck is when you have > an include_path miss. We don't cache misses like this, so if you are > relying on include_path to find your files and you don't hit it on the > first try, you are going to see a bunch of stats. But that is again > something that is easily fixed by not writing crappy code. > > I think that breaking code that looks like this: > > require_once './a.inc'; > require_once 'a.inc'; > require_once '../a.inc'; > require_once 'includes/a.inc'; > > when these all refer to the same a.inc file depending on where the > parent file is and what the coder had for breakfast that morning would > be a very bad idea. > > -Rasmus > Since the realpath cache is only relevant for a single request(right?), removing these lstats calls will a major benefit. Before moving our portal dir to the / dir, ~40% of our page requests were slow on the server side (I'm not sure if my company policies allow me to expose exactly what is considered slow), after moving it ~20% of the page requests were slow! this is significant. And there are still many lstat calls made inside our portal's directory tree. So I think that a php.ini directive for switching off these lstats which will be off by default, will be a great thing. -Amir.
Re: [PHP-DEV] lstat call on each directory level
Arvids Godjuks wrote: Hello. I think this should be optimized. I'm not an expert ofcourse, but as I understood there is only one case witch need a special treatment - require/include _one when a file with equal contents is included from different directories. You can make a switch witch controls if lstat is made or not in these cases. People who know what they are doing will switch it to off and make sure their includes don't result in Fatal error (anyway, to my opinion it is bad desing if such thing happens). Ofcourse open_basedir users will don't have any benefit from it, but that's their choise. So I think you should think it out and make this optimization to 5.3 release. It would be great optimization, IMHO. But all these lstats should be getting cached, so I don't see how it would affect performance very much. If you are blowing your realpath cache, you need to take a look at why that is happening. We probably should disconnect clearstatcache() from the realpath_cache, and we could perhaps look at doing partial path caches through our own realpath implementation. The other thing that can suck is when you have an include_path miss. We don't cache misses like this, so if you are relying on include_path to find your files and you don't hit it on the first try, you are going to see a bunch of stats. But that is again something that is easily fixed by not writing crappy code. I think that breaking code that looks like this: require_once './a.inc'; require_once 'a.inc'; require_once '../a.inc'; require_once 'includes/a.inc'; when these all refer to the same a.inc file depending on where the parent file is and what the coder had for breakfast that morning would be a very bad idea. -Rasmus -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
Hello. I think this should be optimized. I'm not an expert ofcourse, but as I understood there is only one case witch need a special treatment - require/include _one when a file with equal contents is included from different directories. You can make a switch witch controls if lstat is made or not in these cases. People who know what they are doing will switch it to off and make sure their includes don't result in Fatal error (anyway, to my opinion it is bad desing if such thing happens). Ofcourse open_basedir users will don't have any benefit from it, but that's their choise. So I think you should think it out and make this optimization to 5.3 release. It would be great optimization, IMHO.
Re: [PHP-DEV] lstat call on each directory level
There is apc.include_once_override Optimize include_once() and require_once() calls and avoid the expensive system calls used. and apc.stat Be careful if you change this setting. The default is for this to be On which means that APC will stat (check) the script on each request to see if it has been modified. If it has been modified it will recompile and cache the new version. If you turn this setting off, it will not check. That means that in order to have changes become active you need to restart your web server. On a production server where you rarely change the code, turning stats off can produce a significant performance boost. For included/required files this option applies as well, but note that if you are using relative path includes (any path that doesn't start with / on Unix) APC has to check in order to uniquely identify the file. If you use absolute path includes APC can skip the stat and use that absolute path as the unique identifier for the file. You might try APC. It stats, but not so much On Wed, Jul 16, 2008 at 1:20 AM, Rasmus Lerdorf <[EMAIL PROTECTED]> wrote: > Lars Strojny wrote: >> >> Hi Rasmus, >> >> Am Dienstag, den 15.07.2008, 11:40 -0700 schrieb Rasmus Lerdorf: >> [...] >>> >>> That's a realpath() call and it should be getting cached by the realpath >>> cache, so if you are seeing these on every request, try increasing your >>> realpath_cache size in your .ini. Without checking the realpath, you would >>> be able to circumvent open_basedir checking really easily with a symlink. >> >> Couldn't we do that check only if open_basedir is active? > > Like I said, it is used for other things too, like include_once filename > resolution. Check the code. > > -Rasmus > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > > -- Oleg Grenrus -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
Lars Strojny wrote: Hi Rasmus, Am Dienstag, den 15.07.2008, 11:40 -0700 schrieb Rasmus Lerdorf: [...] That's a realpath() call and it should be getting cached by the realpath cache, so if you are seeing these on every request, try increasing your realpath_cache size in your .ini. Without checking the realpath, you would be able to circumvent open_basedir checking really easily with a symlink. Couldn't we do that check only if open_basedir is active? Like I said, it is used for other things too, like include_once filename resolution. Check the code. -Rasmus -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
Hi Rasmus, Am Dienstag, den 15.07.2008, 11:40 -0700 schrieb Rasmus Lerdorf: [...] > That's a realpath() call and it should be getting cached by the realpath > cache, so if you are seeing these on every request, try increasing your > realpath_cache size in your .ini. Without checking the realpath, you > would be able to circumvent open_basedir checking really easily with a > symlink. Couldn't we do that check only if open_basedir is active? cu, Lars signature.asc Description: Dies ist ein digital signierter Nachrichtenteil
Re: [PHP-DEV] lstat call on each directory level
On Tue, 15 Jul 2008, Amir Hardon wrote: > About the issue with the _once, did the patch Derick offered handles > it (I haven't examined it yet). If not, I just need to make sure that > the same file isn't being referenced by two paths and I'm safe right? It does not do any real path checks, so it gives issues when you include the same file with two different paths in the include statement. Your assesment is correct and just making sure you include them the same way does the trick. regards, Derick -- Derick Rethans http://derickrethans.nl | http://ezcomponents.org | http://xdebug.org -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
On Jul 15, 2008, at 2:25 PM, Rasmus Lerdorf wrote: Well, it is used in other places too, like in figuring out _once paths. Including the same file using different paths still needs to be caught. Are you calling clearstatcache() manually anywhere? That blows away the entire realpath cache and completely destroys your performance, so you will want to avoid doing that very often. Based on what I've seen, if the realpath cache gets filled it just quits caching rather than pruning. That seemed odd to me. There was also an issue that Dmitry had fixed in 5.3 a month or so ago where it was caching false finds and filling the cache up more quickly than necessary. I found this out through a quick extension I wrote to view the contents of the realpath cache. If anyone wants to clean this up for inclusion in the core, I'd be more than happy to have it there. You can grab a copy from my Git server: git://git.domain51.com/php.realpath.git -T -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
On Tue, 2008-07-15 at 12:25 -0700, Rasmus Lerdorf wrote:
> Amir Hardon wrote:
> > On Tue, 2008-07-15 at 11:40 -0700, Rasmus Lerdorf wrote:
> >> Amir Hardon wrote:
> >> > I've noticed a weird behavior when doing file access from PHP:
> >> > PHP seems to make an lstat call on each of the parent directories of the
> >> > accessed file, for example see this script:
> >> >
> >> > >> > $fp=fopen("/var/www/metacafe/test","r");
> >> > fclose($fp);
> >> > ?>
> >> >
> >> > When running with strace -e lstat I see this:
> >> > lstat("/var", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
> >> > lstat("/var/www", {st_mode=S_IFDIR|0755, st_size=12288, ...}) = 0
> >> > lstat("/var/www/metacafe", {st_mode=S_IFDIR|0755, st_size=4096, ...}) =
> >> > 0
> >> > lstat("/var/www/metacafe/test", 0x7fbfff9b10) = -1 ENOENT (No such file
> >> > or directory)
> >> >
> >> > Measuring total syscalls time for an apache process on a production
> >> > server, I found out
> >> > that ~33% of the time it spends in syscalls is spent on lstat.
> >> >
> >> > I did a pretty deep web search on the issue and came out with nothing.
> >> > I'll also note that I did a small experiment - moving our root portal
> >> > folder to /,
> >> > this gave an amazing performance improvement!
> >> >
> >> > So my questions are:
> >> > What is the reason for doing these lstat calls?
> >> > How can it be disabled? if not by configuration, maybe by patching php
> >> > (can you direct me to where is this being done in php's source?)
> >>
> >> That's a realpath() call and it should be getting cached by the realpath
> >> cache, so if you are seeing these on every request, try increasing your
> >> realpath_cache size in your .ini. Without checking the realpath, you
> >> would be able to circumvent open_basedir checking really easily with a
> >> symlink.
> >>
> >> -Rasmus
> >
> > I've already increased the realpath_cache to the point it didn't give
> > any more benefit(And it did give benefit),
> > but there are still many lstat calls, and still placing our portal dir
> > in the root directory gave a huge performance benefit(After fine-tuning
> > realpath_cache).
> > We don't use open_basedir.
> >
> > I think it might be wise to make this dir check configurable, as the
> > performance impact is major.
> > Anyway - can you please direct me to the place where this check is made
> > in php's source, so I'll be able to disable it manually?
>
> Well, it is used in other places too, like in figuring out _once paths.
> Including the same file using different paths still needs to be caught.
>
> Are you calling clearstatcache() manually anywhere? That blows away the
> entire realpath cache and completely destroys your performance, so you
> will want to avoid doing that very often.
>
> -Rasmus
>
About clearstatcache() - not using it at all.
Correct me if I'm wrong but this realpath cache is a per-request cache
(when using php as an apache module),
so unless I'm wrong ,the performance benefit I'm getting when moving the
portal to the / dir should be obvious
(our code is splitted to many files, and each file that is being
required, is generating few lstat calls).
About the issue with the _once, did the patch Derick offered handles it
(I haven't examined it yet).
If not, I just need to make sure that the same file isn't being
referenced by two paths and I'm safe right?
(I mean assuming I'll adjust it to php5)
Thanks again to both of you!
-Amir.
Re: [PHP-DEV] lstat call on each directory level
Amir Hardon wrote:
On Tue, 2008-07-15 at 11:40 -0700, Rasmus Lerdorf wrote:
Amir Hardon wrote:
> I've noticed a weird behavior when doing file access from PHP:
> PHP seems to make an lstat call on each of the parent directories of the
> accessed file, for example see this script:
>
>
> $fp=fopen("/var/www/metacafe/test","r");
> fclose($fp);
> ?>
>
> When running with strace -e lstat I see this:
> lstat("/var", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
> lstat("/var/www", {st_mode=S_IFDIR|0755, st_size=12288, ...}) = 0
> lstat("/var/www/metacafe", {st_mode=S_IFDIR|0755, st_size=4096, ...}) =
> 0
> lstat("/var/www/metacafe/test", 0x7fbfff9b10) = -1 ENOENT (No such file
> or directory)
>
> Measuring total syscalls time for an apache process on a production
> server, I found out
> that ~33% of the time it spends in syscalls is spent on lstat.
>
> I did a pretty deep web search on the issue and came out with nothing.
> I'll also note that I did a small experiment - moving our root portal
> folder to /,
> this gave an amazing performance improvement!
>
> So my questions are:
> What is the reason for doing these lstat calls?
> How can it be disabled? if not by configuration, maybe by patching php
> (can you direct me to where is this being done in php's source?)
That's a realpath() call and it should be getting cached by the realpath
cache, so if you are seeing these on every request, try increasing your
realpath_cache size in your .ini. Without checking the realpath, you
would be able to circumvent open_basedir checking really easily with a
symlink.
-Rasmus
I've already increased the realpath_cache to the point it didn't give
any more benefit(And it did give benefit),
but there are still many lstat calls, and still placing our portal dir
in the root directory gave a huge performance benefit(After fine-tuning
realpath_cache).
We don't use open_basedir.
I think it might be wise to make this dir check configurable, as the
performance impact is major.
Anyway - can you please direct me to the place where this check is made
in php's source, so I'll be able to disable it manually?
Well, it is used in other places too, like in figuring out _once paths.
Including the same file using different paths still needs to be caught.
Are you calling clearstatcache() manually anywhere? That blows away the
entire realpath cache and completely destroys your performance, so you
will want to avoid doing that very often.
-Rasmus
--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
On Tue, 15 Jul 2008, Amir Hardon wrote: > On Tue, 2008-07-15 at 11:40 -0700, Rasmus Lerdorf wrote: > > > That's a realpath() call and it should be getting cached by the > > realpath cache, so if you are seeing these on every request, try > > increasing your realpath_cache size in your .ini. Without checking > > the realpath, you would be able to circumvent open_basedir checking > > really easily with a symlink. > > I've already increased the realpath_cache to the point it didn't give > any more benefit(And it did give benefit), but there are still many > lstat calls, and still placing our portal dir in the root directory > gave a huge performance benefit(After fine-tuning realpath_cache). We > don't use open_basedir. > > I think it might be wise to make this dir check configurable, as the > performance impact is major. Anyway - can you please direct me to the > place where this check is made in php's source, so I'll be able to > disable it manually? I've a patch for php 4.3 and 4.4 online - based on a patch by rasmus: http://files.derickrethans.nl/patches/php-4.3-skip-path-checks.patch http://files.derickrethans.nl/patches/php-4.4-skip-path-checks.patch regards, Derick -- Derick Rethans http://derickrethans.nl | http://ezcomponents.org | http://xdebug.org -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] lstat call on each directory level
On Tue, 2008-07-15 at 11:40 -0700, Rasmus Lerdorf wrote:
> Amir Hardon wrote:
> > I've noticed a weird behavior when doing file access from PHP:
> > PHP seems to make an lstat call on each of the parent directories of the
> > accessed file, for example see this script:
> >
> > > $fp=fopen("/var/www/metacafe/test","r");
> > fclose($fp);
> > ?>
> >
> > When running with strace -e lstat I see this:
> > lstat("/var", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
> > lstat("/var/www", {st_mode=S_IFDIR|0755, st_size=12288, ...}) = 0
> > lstat("/var/www/metacafe", {st_mode=S_IFDIR|0755, st_size=4096, ...}) =
> > 0
> > lstat("/var/www/metacafe/test", 0x7fbfff9b10) = -1 ENOENT (No such file
> > or directory)
> >
> > Measuring total syscalls time for an apache process on a production
> > server, I found out
> > that ~33% of the time it spends in syscalls is spent on lstat.
> >
> > I did a pretty deep web search on the issue and came out with nothing.
> > I'll also note that I did a small experiment - moving our root portal
> > folder to /,
> > this gave an amazing performance improvement!
> >
> > So my questions are:
> > What is the reason for doing these lstat calls?
> > How can it be disabled? if not by configuration, maybe by patching php
> > (can you direct me to where is this being done in php's source?)
>
> That's a realpath() call and it should be getting cached by the realpath
> cache, so if you are seeing these on every request, try increasing your
> realpath_cache size in your .ini. Without checking the realpath, you
> would be able to circumvent open_basedir checking really easily with a
> symlink.
>
> -Rasmus
I've already increased the realpath_cache to the point it didn't give
any more benefit(And it did give benefit),
but there are still many lstat calls, and still placing our portal dir
in the root directory gave a huge performance benefit(After fine-tuning
realpath_cache).
We don't use open_basedir.
I think it might be wise to make this dir check configurable, as the
performance impact is major.
Anyway - can you please direct me to the place where this check is made
in php's source, so I'll be able to disable it manually?
Thanks!
-Amir.
Re: [PHP-DEV] lstat call on each directory level
Amir Hardon wrote:
I've noticed a weird behavior when doing file access from PHP:
PHP seems to make an lstat call on each of the parent directories of the
accessed file, for example see this script:
When running with strace -e lstat I see this:
lstat("/var", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
lstat("/var/www", {st_mode=S_IFDIR|0755, st_size=12288, ...}) = 0
lstat("/var/www/metacafe", {st_mode=S_IFDIR|0755, st_size=4096, ...}) =
0
lstat("/var/www/metacafe/test", 0x7fbfff9b10) = -1 ENOENT (No such file
or directory)
Measuring total syscalls time for an apache process on a production
server, I found out
that ~33% of the time it spends in syscalls is spent on lstat.
I did a pretty deep web search on the issue and came out with nothing.
I'll also note that I did a small experiment - moving our root portal
folder to /,
this gave an amazing performance improvement!
So my questions are:
What is the reason for doing these lstat calls?
How can it be disabled? if not by configuration, maybe by patching php
(can you direct me to where is this being done in php's source?)
That's a realpath() call and it should be getting cached by the realpath
cache, so if you are seeing these on every request, try increasing your
realpath_cache size in your .ini. Without checking the realpath, you
would be able to circumvent open_basedir checking really easily with a
symlink.
-Rasmus
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[PHP-DEV] lstat call on each directory level
Hi,
I've noticed a weird behavior when doing file access from PHP:
PHP seems to make an lstat call on each of the parent directories of the
accessed file, for example see this script:
When running with strace -e lstat I see this:
lstat("/var", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
lstat("/var/www", {st_mode=S_IFDIR|0755, st_size=12288, ...}) = 0
lstat("/var/www/metacafe", {st_mode=S_IFDIR|0755, st_size=4096, ...}) =
0
lstat("/var/www/metacafe/test", 0x7fbfff9b10) = -1 ENOENT (No such file
or directory)
Measuring total syscalls time for an apache process on a production
server, I found out
that ~33% of the time it spends in syscalls is spent on lstat.
I did a pretty deep web search on the issue and came out with nothing.
I'll also note that I did a small experiment - moving our root portal
folder to /,
this gave an amazing performance improvement!
So my questions are:
What is the reason for doing these lstat calls?
How can it be disabled? if not by configuration, maybe by patching php
(can you direct me to where is this being done in php's source?)
Thanks!
-Amir.
