Sterling, you still seem to be afraid to benchmark sqlite vs mysql or
postgresql sessions.
Also, 150+ req/s is more than most people will ever have hitting their
sites.
Yes, so you fixed some segfaults (are you going to commit that?) but keep in
mind that the code is in the HEAD branch and was only written this morning.
You can't argue for bundling of sqlite and then argue against the inclusion
of some simple C code that provides a feature that some people will find
useful, even if you don't find it useful.
Yes, "enterprise" sites would be stupid to use sqlite for session storage,
but then, enterprise sites probably won't be using sqlite at all.
--Wez.
----- Original Message -----
From: "Sterling Hughes" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: "Sascha Schumann" <[EMAIL PROTECTED]>; "Wez Furlong"
<[EMAIL PROTECTED]>
Sent: Tuesday, July 01, 2003 8:28 PM
Subject: [PHP-DEV] Removing SQLite sessions from the default distribution
> Hi,
>
> Recently sqlite sessions have been added by default. I think this is a
> bad idea to have as a default handler. SQLite is not designed for a
> write intensive environment, and encouraging such usage seems to be
> silly.
>
> SQLite is bad because:
>
> 1) It uses one file for the entire db. Therefore, every time *any*
> session is updated, all sessions must be locked. This means that if you
> have session a and session b in two separate processes, they must be
> updated one at a time, instead of together. Furthermore, this clusters
> terribly, requiring all locks to happen on a single file across a
> cluster(*).
>
> It also means that if one session gets corrupted, all your sessions will
> be corrupted. If a session file gets removed, then you've lost all
> your session files.
>
> 2) It offers not one practical advantage. When asking the proponents of
> SQLite based sessions, they said the advantage is that everything is in
> one file.
>
> That's the disadvantage.
>
> Having a single point of access, single point of failure, single point
> of performance degradation is a never a good thing, especially if it
> buys you nothing. After fixing the extension (the CVS version is
> broken), I did some benchmarks on the following script:
>
> <?php
> mt_srand();
> session_id(mt_rand(0, 300));
> session_start();
> if (!isset($_SESSION['counter'])) {
> $_SESSION['counter'] = 0;
> } else {
> $_SESSION['counter']++;
> }
> echo $_SESSION['counter'];
> ?>
>
> With sqlite synchronization enabled, I got ::
>
> files = 410-440 req/s
> sqlite = 33-35 req/s
>
> With synchronization disabled, I got ::
>
> files = 410 - 440 req/s
> sqlite = 150-179 req/s
>
> That's a very signifigant slowdown, and it wins you nothing. A base
> script ::
>
> <?php
> echo $i++;
> ?>
>
> Gets 520 req/s on my machine.
>
> 3) Writing the code in C gains you nothing. Its not like you'll be
> gaining req/s if the code is in a C session handler vs. a PHP session
> handler. The C code is also harder to maintain. For example, in order
> to prove that sqlite sessions were slow and otherwise crappy, I had to
> "fix" 3 segfaults in the session handler code, and change the queries
> around.
>
> If we want SQLite sessions, I submit this should be in a PEAR class or a
> PECL handler (like with PostgreSQL). SQLite sessions should not be a
> recommended method, they don't gain you anything, and at the same time
> they hurt you performance-wise. Having users who really want it, go:
>
> # pear install SQLite_Session
>
> Is not a hard cross to bear, and considering that sqlite enabled
> sessions should be avoided in the first place, I think its a bad idea to
> include them by default.
>
> -Sterling
>
> (*) You may argue "don't cluster sqlite sessions." That's not a good
> thing. Fine, don't cluster sqlite sessions, but that's a negative,
> against sqlite.
--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: http://www.php.net/unsub.php
