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Major refactoring of queue handlers to support running multiple sites in one daemon.

Browse Source 
Key changes:
* Initialization code moved from common.php to StatusNet class;
  can now switch configurations during runtime.
* As a consequence, configuration files must now be idempotent...
  Be careful with constant, function or class definitions.
* Control structure for daemons/QueueManager/QueueHandler has been refactored;
  the run loop is now managed by IoMaster run via scripts/queuedaemon.php
  IoManager subclasses are woken to handle socket input or polling, and may
  cover multiple sites.
* Plugins can implement notice queue handlers more easily by registering a
  QueueHandler class; no more need to add a daemon.

The new QueueDaemon runs from scripts/queuedaemon.php:

* This replaces most of the old *handler.php scripts; they've been refactored
  to the bare handler classes.
* Spawns multiple child processes to spread load; defaults to CPU count on
  Linux and Mac OS X systems, or override with --threads=N
* When multithreaded, child processes are automatically respawned on failure.
* Threads gracefully shut down and restart when passing a soft memory limit
  (defaults to 90% of memory_limit), limiting damage from memory leaks.
* Support for UDP-based monitoring: http://www.gitorious.org/snqmon

Rough control flow diagram:
QueueDaemon -> IoMaster -> IoManager
                           QueueManager [listen or poll] -> QueueHandler
                           XmppManager [ping & keepalive]
                           XmppConfirmManager [poll updates]

Todo:

* Respawning features not currently available running single-threaded.
* When running single-site, configuration changes aren't picked up.
* New sites or config changes affecting queue subscriptions are not yet
  handled without a daemon restart.
* SNMP monitoring output to integrate with general tools (nagios, ganglia)
* Convert XMPP confirmation message sends to use stomp queue instead of polling
* Convert xmppdaemon.php to IoManager?
* Convert Twitter status, friends import polling daemons to IoManager
* Clean up some error reporting and failure modes
* May need to adjust queue priorities for best perf in backlog/flood cases

Detailed code history available in my daemon-work branch:
http://www.gitorious.org/~brion/statusnet/brion-fixes/commits/daemon-work
This commit is contained in:
Brion Vibber
2010-01-12 19:57:15 -08:00
parent 2b10e359fe
commit ec145b73fc
39 changed files with 2612 additions and 1203 deletions
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23
classes/Memcached_DataObject.php
View File

@@ -331,6 +331,29 @@ class Memcached_DataObject extends DB_DataObject
$exists = false;
}
// @fixme horrible evil hack!
//
// In multisite configuration we don't want to keep around a separate
// connection for every database; we could end up with thousands of
// connections open per thread. In an ideal world we might keep
// a connection per server and select different databases, but that'd
// be reliant on having the same db username/pass as well.
//
// MySQL connections are cheap enough we're going to try just
// closing out the old connection and reopening when we encounter
// a new DSN.
//
// WARNING WARNING if we end up actually using multiple DBs at a time
// we'll need some fancier logic here.
if (!$exists && !empty($_DB_DATAOBJECT['CONNECTIONS'])) {
foreach ($_DB_DATAOBJECT['CONNECTIONS'] as $index => $conn) {
if (!empty($conn)) {
$conn->disconnect();
}
unset($_DB_DATAOBJECT['CONNECTIONS'][$index]);
}
}
$result = parent::_connect();
if ($result && !$exists) {