Sample Simple Stupid Redis Message Queue Producer Consumer Example

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Java 8 CompletableFuture parallel tasks and Timeout example

Suppose that you have a list of item (id list referring to a table, url list to fetch page data from internet, customer keys for location query from a map service  etc...). And you will start some parallel tasks  for those ids. But you don't want to wait no longer than your threshold. Also you want to collect the data from the returned "CompletableFutures" which are not timed out.

How can you achieve this while using a CompletableFuture ?

PS: There is no .orTimeout ()  option in Java 8. It is included in Java10.  And other option is using .get(N, TimeUnit.SECONDS) but it will not gave you what you want.

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Outputs : 

pool-1-thread-1 - - > will sleep for secs :0

Duration here = 233

pool-1-thread-2 - - > will sleep for secs :1000

pool-1-thread-3 - - > will sleep for secs :2000

pool-1-thread-4 - - > will sleep for secs :3000

pool-1-thread-5 - - > will sleep for secs :4000

pool-1-thread-6 - - > will sleep for secs :5000

Collected Results = [0, 1000, 2000, 3000, 4000, 5000, null, null, null, null]

Total Duration = 5235

How did i come here :) See below code pls
In this example your main thread will be waiting 2 seconds for each uncompleted future.
I guess N*2 seconds waiting is not the thing that you expect to see here
And yes.. There is 20 seconds duration job and it is cancelled You have a minimal gain at that point but ! But if you would have 20 tasks ...The picture would be very nagative again .

Outputs : 

ForkJoinPool.commonPool-worker-1 - - > will sleep : 0
ForkJoinPool.commonPool-worker-5 - - > will sleep : 4
ForkJoinPool.commonPool-worker-3 - - > will sleep : 2
ForkJoinPool.commonPool-worker-4 - - > will sleep : 3
ForkJoinPool.commonPool-worker-7 - - > will sleep : 6
ForkJoinPool.commonPool-worker-1 - - > will sleep : 5
ForkJoinPool.commonPool-worker-2 - - > will sleep : 1
ForkJoinPool.commonPool-worker-6 - - > will sleep : 7
Tasks are created here, duration = 79
Getting results
Getting results
Getting results
ForkJoinPool.commonPool-worker-2 - - > will sleep : 8
Getting results
ForkJoinPool.commonPool-worker-3 - - > will sleep : 9
Getting results
ForkJoinPool.commonPool-worker-4 - - > will sleep : 20
Getting results
Getting results
Getting results
Getting results
Getting results
Getting results
Total duration = 13080
CollectedResults = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, java.util.concurrent.TimeoutException]

weak wifi , remote jmx

................HOW TO SEE CONNECTION POOL STATS ON COMMAND LINE VIA JMX ............................

Tool page : https://nofluffjuststuff.com/blog/vladimir_vivien/2012/04/jmx_cli_a_command_line_console_to_jmx

wget https://github.com/downloads/vladimirvivien/jmx-cli/jmxcli-0.1.2-bin.zip
unzip jmxcli-0.1.2-bin.zip
cd jmxcli-0.1.2
java -jar cli.jar
cp /usr/lib/jvm/java-8-oracle/lib/tools.jar lib/
chmod 777 lib/tools.jar 
list filter:"com.mchange.v2.c3p0:type=PooledDataSource*" label:true
desc bean:$0
exec bean:"com.mchange.v2.c3p0:type=PooledDataSource[z8kflt9w1cicerh10mnh44|20c29a6f]" get:"numBusyConnections"
exec bean:"com.mchange.v2.c3p0:type=PooledDataSource[z8kflt9w1jggz5o1xv9pi5|2101f18a]" get:"numBusyConnections"