Generally the Cron plugin will run if there's still execution time for
1 second since starting the Action processing. If you want to change
this (such as disabling, 0 seconds, or maybe running bigger chunks,
for like 4 seconds) you can do this, where 'n' is time in seconds.
addPlugin('Cron', array('secs_per_action', n));
Add 'rel_to_pageload'=>false to the array if you want to run the queue
for a certain amount of seconds _despite_ maybe already having run that
long in the previous parts of Action processing.
Perhaps you want to run the cron script remotely, using a machine capable
of background processing (or locally, to avoid running daemon processes),
simply do an HTTP GET request to the route /main/cron of your GNU social.
Setting secs_per_action to 0 in the plugin config will imply that you run
all your queue handling by calling /main/cron (which runs as long as it can).
/main/cron will output "0" if it has finished processing, "1" if it should
be called again to complete processing (because it ran out of time due to
PHP's max_execution_time INI setting).
The Cron plugin also runs events as close to hourly, daily and weekly
as you get, based on the opportunistic method of running whenever a user
visits the site. This means of course that the cron events should be as
fast as possible, not only to avoid delaying page load for users but
also to minimize the risk of running into PHP's max_execution_time. One
suggestion is to only use the events to add new queue items for later processing.
These events are called CronHourly, CronDaily, CronWeekly - however there
is no guarantee that all events will execute, so some kind of failsafe,
transaction-ish method must be implemented in the future.
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
