Re: [jetty-users] Client threads - can they be daemon threads?

[Shawn Heisey <eclipse@xxxxxxxxxxxx>]

On 6/14/23 11:05, Simone Bordet wrote:
> It is already available:
>
> QueuedThreadPool threadPool = new QueuedThreadPool(...);
> threadPool.setDaemon(true);
>
> HttpClient httpClient = new HttpClient();
> httpClient.setExecutor(threadPool);
> httpClient.start();

Is that Jetty code?

This is the code in SolrJ's "Http2SolrClient" that creates the jetty client:

https://paste.elyograg.org/view/e4c9ede9

I suspect that the code path quoted above is not being used by SolrJ, 
that SolrJ is managing the thread pool and is not creating threads with 
the daemon flag.  If I am wrong, then this info/query will be valid:

-
I was able to access source for QueuedThreadPool in my IDE for my 
project using SolrJ.  I see that the boolean flag (_daemon) changed by 
the setDaemon call is being used when a new thread is created.  Is there 
any chance that the _daemon field in QueuedThreadPool is having thread 
safety problems?  If it were me doing this, I would use AtomicBoolean 
rather than boolean for that, even if I thought there couldn't possibly 
be thread safety issues.
-

Should SolrJ just let Jetty handle its own thread pool?  Is that pool 
object MDC aware?  MDC awareness is the only reason I can imagine that 
somebody thought it was a good idea for SolrJ to handle Jetty threads 
itself.  I do not see anything in the executor objects used by SolrJ 
that would cause it to create daemon threads.

Thanks,
Shawn