Admin FAQ

FIFO

What is FIFO ?

FIFO in harvester is an optional feature that harvester agents can take advantage of message queue data structure. Main purpose FIFO is to reduce DB polling frequency and lower CPU usage of the node.

The FIFO has "Priority Queue" data structure. Different plugins can be chosen as fifo backend. Existing plugins: SQLite, Redis

So far, only monitor agent has option to enable FIFO. The monitor FIFO allow configurable priority of each PQ. Worker chunks with shorter fifoCheckInterval has higher priority and will be checked more frequently.

How to set up FIFO ?

Choose a FIFO backend and set up related service. Then, configure in harvester.

SQLite

Backend setup:

• Make sure sqlite3 is installed in OS.
• No special service configuration required.

Harvester configuration:

• In panda_harvester.cfg, [fifo] section, one should set fifoModule = pandaharvester.harvesterfifo.sqlite_fifo and fifoClass = SqliteFifo to use the SqliteFifo fifo plugin.

• The database_filename should be specified as the database filename for sqlite. This must be different from main Harvester DB and other fifo DBs if using sqlite.

• It is recommended to use placeholder $(AGENT) in filename to make different DBs for fifo of different agents.

• One can set DB file located in ramdisk for better performance.

• E.g.

  [fifo]
  fifoModule = pandaharvester.harvesterfifo.sqlite_fifo
  fifoClass = SqliteFifo
  database_filename = /dev/shm/$(AGENT)_fifo.db
  

Redis

Backend setup:

• Make sure the redis service is installed, configured, and running on the harvester node.

• Install python redis via pip within harvester python venv:

  $ pip install redis
  

Harvester configuration:

• In panda_harvester.cfg, [fifo] section, one should set fifoModule = pandaharvester.harvesterfifo.redis_fifo and fifoClass = RedisFifo to use the RedisFifo fifo plugin. This configuration is enough here if one sets up a standalone redis service on localhost with default port, without password nor db specified.

• If the redis service has specific host, port, db, and password, then respectively set redisHost, redisPort, redisDB, redisPassword accordingly.

• E.g.

  [fifo]
  fifoModule = pandaharvester.harvesterfifo.redis_fifo
  fifoClass = RedisFifo
  

Test and benchmark:

(TODO)