I'm still curious what people think here. As I stare at this longer,
I'd like to be able to call RiakNode.checkHealth(), but it's private.
HealthMonitorTask.run that only calls checkHealth some of the time, so
without the ability to call it directly, I think I'm getting a stale
notion of health in circumstances like I outlined below -- when the last
operation was successful, but the node has since gone down.
Thanks for your input.
-DB
On 12/2/15 10:25 PM, David Byron wrote:
I'm implementing a health check for a service of mine that uses riak.
I've seen this code from
https://github.com/basho/riak-java-client/issues/456:
RiakCluster cluster = clientInstance.getRiakCluster();
List<RiakNode> nodes = cluster.getNodes();
for (RiakNode node : nodes)
{
State state = node.getNodeState();
}
and it's great. From what I can tell, it depends on some background
processing that keeps track of the state of the nodes. I did a quick
test though, and if I run 'riak stop' from the command line and then
this loop with no intervening operations, the nodes report RUNNING. Even
after some time passes (more than three minutes), still RUNNING.
However, if I run do run an intervening operation (some actual query of
data for example) that fails, the nodes then report HEALTH_CHECKING.
Then, after 'riak start', the nodes report RUNNING again. I suppose
that's good.
So, I'm trying to decide how to implement the health check. The above
loop doesn't seem to be enough, but do I really need to do something like:
final RiakFuture<Void, Void> future = cluster.execute(new PingOperation());
try {
future.await();
future.get();
} catch (ExecutionException | InterruptedException e) {
// bad
}
// good
Maybe it's sufficient to only do this if all the nodes report RUNNING? I
suppose there's always a small window in time where a node could report
bad, but via a ping I'd learn it was up...so I'm torn. Any suggestions
for whether pinging every time is correct, or there's something more
efficient (and safe)?
Thanks for your help.
-DB
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