1. Use a props file such as the following:
# a = agent
# r = source
# c = channel
# k = sink
a1.sources = r1
a1.channels = c1
a1.sinks = k1
a1.sources.r1.type = NETCAT
a1.sources.r1.channels = c1
a1.sources.r1.bind = localhost
a1.sources.r1.port = 1473
a1.channels.c1.type = MEMORY
a1.sinks.k1.type = NULL
a1.sinks.k1.channel = c1
2. Set the FLUME_CONF_DIR to point to your conf dir
[will@localhost flume-1.2.0-incubating-SNAPSHOT]$ export FLUME_CONF_DIR=/home/will/git/apache/flume/flume-1.2.0-incubating-SNAPSHOT/conf
3. Create a flume-env.sh file
[will@localhost flume-1.2.0-incubating-SNAPSHOT]$ cp conf/flume-env.sh.template conf/flume-env.sh
4. Adjust the memory size within flume-env.sh (this file will be automatically sourced when calling bin/flume-ng, but only if you've specified the FLUME_CONF_DIR env var)
(here, I went to the extreme and I set the min and max heap to 1GB. I also specified a YourKit profiler agent)
Sample contents of flume-env.sh:
export JAVA_OPTS="-Xms1024m -Xmx1024m -agentpath:/home/will/tools/yjp-10.0.6/bin/linux-x86-64/libyjpagent.so=tracing,noj2ee"
5. Run the flume NG agent:
bin/flume-ng node --conf conf --conf-file conf/a1.properties --name a1
6. Open-up 10 terminal windows (on the same host) to connect to the netcat server port. Sent continuous output in each terminal. I chose to use the command:
yes | nc localhost 1473
The "yes" unix cmd will continuously output 'y' char, followed by newline char. If you use YourKit and go into the Threads view, you'll see that after a while (possibly need to wait up to 10 mins) after a netcat handler thread has continuously been alternating between Runnable and Blocked states (blocking due to org.apache.klog4j.Category.log(..), but that's beside the point), the netcat handler thread enters a continuous wait state for exactly 1 minute, and then terminates (while its associated 'yes | nc localhost 1473' command is still running).
I haven't done further analysis. My first thought was a thread safety issue. Note that there are no property file reconfigurations done during this test – I leave the props file alone.
I welcome your ideas/comments. I initially ran this test with the default -Xmx20m but it ran out of memory. For a future test I might lower the Xmx/Xms from 1GB to maybe 128MB.