The following document describes some common resource problems that may be associated with the Fan-Out driver handling large numbers of platforms. Receiver and driver suggestions are detailed and explained within this technical document.
Platform Receiver Run Modes#As the Fan-Out driver to Platform Receiver connection is a secured connection it is important to not overlook the overhead of creating a secure connection. Running the platform receiver in polling mode or in scheduled mode at small intervals (less than
Persistent mode#Persistent mode is the default mode for Fan-Out platform receivers. This mode allows the receiver to make a connection to the fan-out driver and keep the connection open until the receiver is shutdown.
Because the connection remains open, this mode can accumulate a lot of open connections to the fan-out driver. See Fan-Out Driver and File Descriptors for information about tuning the driver to support large numbers of persistent platform connections. The obvious advantage of persistent mode is that platforms are notified with events in real time as they occur.
Polling mode#Polling mode allows for a Fan-Out platform receiver to open a connection to the Fan-Out driver, poll for events and disconnect. This occurs on an interval, which is configurable through the platform configuration file.
The advantage of polling allows for the fan-out driver to handle a lot of incoming platforms but not accumulate memory and file descriptor resources involved with keeping a connection actively established. However, if the interval is too low, the Fan-Out driver may be consuming just as many memory and CPU resources by performing LDAP searches too frequently. If you plan to involve more than 400 platforms for a single Fan-Out driver, it's recommended to use polling mode and keep polling intervals to at least 30 minutes. The disadvantage here is that events may take up to 30 minutes to receive on the platform. Decreasing that recommended interval is simply contingent on the amount of CPU and memory resources available by the Fan-Out driver; in addition, multiple core drivers may be added to balance this load.
Scheduled mode#Scheduled mode tells the Fan-Out platform receiver to "run once"; that is, connect receive events, disconnect and shutdown. This mode is favorable to be run from a cron job that wishes to receive events on specific times of the day.
The scheduled mode also shares the same properties as the polling mode. However, by using cron to establish run-times, receivers may be configured to poll in staggered batches, which can spread out the CPU and memory resources needed by the Fan-Out driver to process platform requests.