FAST ESP - FSIS

I happened to troubleshoot an issue with "FAST ESP - FSIS" . The Syslog has been repeatedly logging the following warning msgs & the CTSFlows were running forever without any progress & no errors (kinda stuck there).

• Subsystem operation queue full (session xxx, ops yyyy->zzzz), sleeping xx seconds before resubmitting operation set... 
• session_status (235): Sparequeue too full for operation of size 53879040 from session id xxx
• api_queue: Apiqueue too full for operation of size 53879040 from session id xxx
• api_queue: The operation with session id xxx and size of 53879040 bytes is larger than the configured max api queue size of 52428800 bytes. Please reduce batch size or increase max api queue size for optimal performance.  

These information struck me to look & change API queue size and that lead me to these MSDN support articles

http://support.microsoft.com/kb/2017114
http://support.microsoft.com/kb/2535170 

Changes are :

1. %FASTSEARCH%\etc\config_data\RTSearch\webcluster\rtsearchrc.xml.
in Admin Server Only => Added  maxQueueSize="524288000" (in bytes, i.e 500 MB) to the <options...> node and save the file

2. Reload the configuration from the AdminServer Node: Syntax: nctrl reloadcfg

3. Restart of all indexer processes (in all the Nodes whereever "RTS Indexer" is configured and running).
Use "nctrl stop indexer" and "nctrl start indexer" from all indexer nodes or via the System Management tab in the ESP Admin GUI.

Following these changes, CTSFlow, and nodes all just started working.