Transactions are critical concept for FlumeNG.
Sources produce events into Channel based on transaction batch size.
Sinks consume events from Channel based on transaction batch size.
It means the batch size is the key for performance tuning.
For agent.
ExecSource is used to collect events and the default batch size is 20. In order to do it in real time, it’s better we set it to 5 or 10. It will be based on the log itself.
AvroSink is used to transmit events into collectors. So the batch size is N times as the ExecSource batch size.
For collector.
HbaseSink batch size is suggested to 100.
And we can adjust the batch size based on our test results.
The larger of the batch size, the better the file channels operate; but we should consider the latency.
The smaller of the batch size, the faster of the transmitting ; but we should consider the CPU and time consumed of disk sync.
Please ref below blogs to get more.
http://blog.cloudera.com/blog/2013/01/how-to-do-apache-flume-performance-tuning-part-1/
http://blog.cloudera.com/blog/2012/09/about-apache-flume-filechannel/