XCache causes white screen of death

I need to look into this. I deprecated the XCache module so I need to get this working.... Patches welcome ... :)

@greg.harvey have you tried xcache 1.2.2? When I test this under centos 5 I build it from source and that works.

@greg.harvey we are using php and other from remi repo (blog.famillecollet.com/pages/Config-en)

This one from centos 4 server

php.i386                                 5.2.6-1.el4.remi
php-pecl-memcache.i386                   3.0.2-1.el4.remi

Has there been any changes on this? i am having the same error in an ubuntu intrepid server.
Drupal 6.
PHP 5.2.6-2ubuntu4
Cache Router beta8
XCache 1.2.2-2

is there any performance differences between xcache and memcached? i thought xcache was supposed to be faster, but if xcache was depreciated because its not up to par then i will just switch to memcached

I'm getting a WSOD with a 500 error using Xcache (version 1.2.2, built from FreeBSD's ports collection). This seems to be caused by reading the data from the cache, because if I empty the cache from Xcache's admin pages (not this module's) or by restarting the web server, everything works fine for the first subsequent Drupal page load; it's only on the second when things go horribly, horribly wrong.

Here's my error log (I'm using Lighty):

2009-05-20 15:46:23: (mod_fastcgi.c.2494) unexpected end-of-file (perhaps the fastcgi process died): pid: 82399 socket: unix:/var/run/lighttpd/php-fastcgi.socket-0 
2009-05-20 15:46:23: (mod_fastcgi.c.3326) response not received, request sent: 1224 on socket: unix:/var/run/lighttpd/php-fastcgi.socket-0 for /index.php , closing connection 
2009-05-20 15:46:52: (mod_fastcgi.c.2494) unexpected end-of-file (perhaps the fastcgi process died): pid: 82399 socket: unix:/var/run/lighttpd/php-fastcgi.socket-0 
2009-05-20 15:46:52: (mod_fastcgi.c.3326) response not received, request sent: 1199 on socket: unix:/var/run/lighttpd/php-fastcgi.socket-0 for /index.php , closing connection

…etc.

Has anyone out there managed to get this module to work with Xcache? I'd prefer to use Xcache because I'm already familiar with it, but I'll move to a different caching system if necessary. Either way, if Xcache compatibility with this module is simply broken, it'd be nice if that fact were stated on the project page…

After further fiddling, I'm convinced this problem (or my iteration of it, anyway) is not caused by Cache Router, but by XCache itself - or at least something else on a lower level. This is because I can get the problem to occur by writing my own scripts calling xcache_get(), or by trying to load the variable through XCache's admin interface.

I've posted a thread on XCache's forum pleading for help. The main developer "moo" is usually pretty active there, so hopefully we'll get some answers, or at least some hints, soon.

The issue seems to be related to the fact that xcache currently does not store object in variable cache. Attempting to get and store the object therefore is segfaulting the php process. Ref: http://xcache.lighttpd.net/wiki/XcacheApi

This patch should fix it for now by serializing everything. I think the memory handling can still use some work as it doesn't fail gracefully if insufficient var memory is available.

Light testing with this patch has been successful so far. Thanks, janicel!

Does this mean that XCache has never worked as intended in Cache Router before?

I honestly don't know. The code for xcache looks like it was adapted from the APC code. I suspect that the xcache portion was rarely used/tested and most people were using APC.

$cache->serialized should be FALSE so change

-    if (!is_string($value)) {
-      $cache->serialized = TRUE;
-      $cache->data = serialize($value);
-    }
-    else { 
-      $cache->serialized = FALSE;
-      $cache->data = $value;
-    }
+    $data = serialize($cache);

to

-    if (!is_string($value)) {
-      $cache->serialized = TRUE;
-      $cache->data = serialize($value);
-    }
-    else { 
-      $cache->serialized = FALSE;
-      $cache->data = $value;
-    }
+    $cache->serialized = FALSE;
+    $data = serialize($cache);

Another issue with using $ttl parameter - drupal use 3 kinds: -1, 0, and time() + ttl
For xcache you should check $expire

    if ($expire == CACHE_TEMPORARY) {
      $ttl = 180;
    }
    elseif ($expire > 0) {
      $ttl = $expire - time();
    }
    else {
      $ttl = $expire;
    }
    ...........
    $cache->expire = $expire;
    ...........
      // Attempt to store full key and value
      if (!xcache_set($this->key($key), $cache, $ttl)) {

This should catch both of the issues you raised.

after applying the patch I still got a WSOD.. hmm, anyone else having the same problem??

Can you give a bit more details about your setup? Any message in the web server error log? How big is your xcache variable cache?

Applied patch, may need a bit more testing to get XCache working correctly. It has definitely been the red-headed step-child of the group as it's hardly used. Will do more thorough testing to make sure this is actually working. Thanks for all the hard work on this!

rc1 with this patch aint no working =(
i still have error:
Fatal error: Call to undefined function xcache_get() in path/mysite.com/sites/all/modules/cacherouter/engines/xcache.php on line 35
dont know what to do.