Dockerfile for a container containing JGroups and a couple of demos.
To run the image directly, execute
docker -it belaban/jgroups
To build the image, run
docker build .
The demos are described below. The idea is to run the demo apps in a container each on the same host and they will form a cluster.
To run it:
chat [-name name], e.g. chat -name A
Run the Chat application in multiple containers on the same host and they will form a cluster. Typing a message into one Chat will send it to all other chats
Distributed locks are implementations of
java.util.concurrent.locks.Lock and provide locks that can be
accessed from all nodes in a cluster.
A typical use case is to lock a resource so that only 1 thread in a given node in the cluster can access it. Should a node crash while holding a lock, the lock is released immediately.
For more details, see the section on distributed locks at http://www.jgroups.org/manual/index.html#LockService.
To run the lock demo, type:
lock [-name name]
Typing help into the shell shows a few commands:
[jgroups@b21d0fa6c79d ~]$ lock -name A
-------------------------------------------------------------------
GMS: address=A, cluster=lock-cluster, physical address=172.17.0.178:52519
-------------------------------------------------------------------
: help
LockServiceDemo [-props properties] [-name name]
Valid commands:
lock (<lock name>)+
unlock (<lock name> | "ALL")+
trylock (<lock name>)+ [<timeout>]
Example:
lock lock lock2 lock3
unlock all
trylock bela michelle 300
:
If you start instances A and B, you can try out the following:
- A:
lock printer - B:
lock printer// will block - A:
unlock printer// now B will get the lock
Or a lock holder can be killed:
- A:
lock printer - B:
lock printer - Kill A. B will now get the lock on "printer"
Distributed counters are counters will can be atomically incremented, decremented, compare-and-set etc across a cluster.
To run the demo:
count [-name name]
Run multiple instances in different containers. The demo uses a counter named "mycounter" and there's a command prompt which shows the commands to be executed.
Questions can be asked on the users or dev mailing lists: https://sourceforge.net/p/javagroups/mailman.
Enjoy !
Bela Ban
