[jboss-as7-dev] Limiting Server Thread Usage

[Jason T. Greene]

Moving to a new thread.

The big problem we run into with this is that almost every application 
of a thread pool that we have needs to be highly tailored to its usage 
to get the most optimal performance. So we end up with quite a few 
different pools and it becomes difficult to impose a server wide limit.

There however some potential strategies we could take. Although I am 
unsure as to how the overall effectiveness would be:

1. Sharing idle threads between pools
2. Force everything to go through a special blocking thread factory via 
instrumentation of java.lang.Thread. Any attempt to allocate over the 
max would lead to thread reclamation attempts and finally blocking until 
a timeout is reached.
3. Some kind of auto-tuning weighting model. If the max total threads is 
N, force all thread pools to use a percentage of N, potentially based on 
establishing current config value divided by combined total.

One thing I wonder though is if cloud providers are "barking up the 
wrong tree"? It seems a better limitation of an application is raw CPU 
clock time and max memory usage. How they split that time into threads 
doesn't really affect the scalability of the physical server, it's all 
virtual process performance (who cares if someone wastes time context 
switching?).

On 9/14/11 10:39 AM, Scott Stark wrote:
 > The other big cross cutting concern is controlling the total number of
 > threads in use by the application server. When running under a
 > constrained environment that uses something like pam_limits module to
 > control how many process(==java threads) a user can have, it is
 > difficult to know what the server max thread usage is right now.
 >

-- 
Jason T. Greene
JBoss AS Lead / EAP Platform Architect
JBoss, a division of Red Hat