Thread Pool for EJB works unexpectedly
Hi,
I looked at /subsystem=ejb3/thread-pool=default. It is used when EJBs are invoked from a remote client:
After the starting JBoss it shows:
/subsystem=ejb3/thread-pool=default:read-resource(include-runtime=true)
{
"outcome" => "success",
"result" => {
"active-count" => 0,
"completed-task-count" => 0L,
"current-thread-count" => 0,
"keepalive-time" => {
"time" => 100L,
"unit" => "MILLISECONDS"
},
"largest-thread-count" => 0,
"max-threads" => 10,
"name" => "default",
"queue-size" => 0,
"rejected-count" => 0,
"task-count" => 0L,
"thread-factory" => undefined
}
I have an ejb that just waits for a few seconds and I start a client that uses two paralles threads which loop and call the ejb.
I would expect that I get the following values while the client runs:
"active-count" => 2,
"current-thread-count" => 2,
"largest-thread-count" => 2,
"max-threads" => 10,
The thread-count should not be larger than 2 (or a little higher) since I expect the threads to be reused. However I get:
"active-count" => 2,
"completed-task-count" => 2L,
"current-thread-count" => 4,
"keepalive-time" => {
"time" => 100L,
"unit" => "MILLISECONDS"
},
"largest-thread-count" => 4,
"max-threads" => 10,
"name" => "default",
"queue-size" => 0,
"rejected-count" => 0,
"task-count" => 4L,
Next:
"active-count" => 2,
"completed-task-count" => 4L,
"current-thread-count" => 6,
"keepalive-time" => {
"time" => 100L,
"unit" => "MILLISECONDS"
},
"largest-thread-count" => 6,
"max-threads" => 10,
"name" => "default",
"queue-size" => 0,
"rejected-count" => 0,
"task-count" => 6L,
Next:
"active-count" => 2,
"completed-task-count" => 6L,
"current-thread-count" => 8,
"keepalive-time" => {
"time" => 100L,
"unit" => "MILLISECONDS"
},
"largest-thread-count" => 8,
"max-threads" => 10,
"name" => "default",
"queue-size" => 0,
"rejected-count" => 0,
"task-count" => 8L,
Next:
"active-count" => 2,
"completed-task-count" => 8L,
"current-thread-count" => 10,
"keepalive-time" => {
"time" => 100L,
"unit" => "MILLISECONDS"
},
"largest-thread-count" => 10,
"max-threads" => 10,
"name" => "default",
"queue-size" => 0,
"rejected-count" => 0,
"task-count" => 10L,
Indeed 10 threads are created even when only two are used at the same time:
jstack 4381 | grep EJB
"EJB default - 10" prio=10 tid=0x00007fef540bb800 nid=0x12dc waiting on condition [0x00007fef4d6c1000]
"EJB default - 9" prio=10 tid=0x0000000041f4a800 nid=0x12db waiting on condition [0x00007fef4d8c3000]
"EJB default - 8" prio=10 tid=0x00007fef3805f800 nid=0x12da waiting on condition [0x00007fef4d3a7000]
"EJB default - 7" prio=10 tid=0x00007fef3805e000 nid=0x12d9 waiting on condition [0x00007fef4ce17000]
"EJB default - 6" prio=10 tid=0x00007fef540b9000 nid=0x12d8 waiting on condition [0x00007fef4c50d000]
"EJB default - 5" prio=10 tid=0x0000000041fd3000 nid=0x12d7 waiting on condition [0x00007fef4cb31000]
"EJB default - 4" prio=10 tid=0x00007fef44047000 nid=0x12d4 waiting on condition [0x00007fef4cf61000]
"EJB default - 3" prio=10 tid=0x00007fef38067800 nid=0x12d3 waiting on condition [0x00007fef4d7c2000]
"EJB default - 2" prio=10 tid=0x00007fef540ae800 nid=0x12d2 waiting on condition [0x00007fef4c89a000]
"EJB default - 1" prio=10 tid=0x00007fef540a4000 nid=0x12d1 waiting on condition [0x00007fef4d1a3000]
The second unexpeded beehavior is that the threads are not removed after keepalive-time:
"keepalive-time"
"description" => "Used to specify the amount of time that pool threads should be kept running when idle; if not specified, threads will run until the executor is shut down."
Although the time is specified, the threads stay forever.
The third thing is related to the documentation of max-threads:
"max-threads" => {
"restart-required" => "no-services"
When I change this without restart and start a client with lots of parallel threads, I get:
"active-count" => 10,
"completed-task-count" => 155L,
"current-thread-count" => 10,
"keepalive-time" => {
"time" => 100L,
"unit" => "MILLISECONDS"
},
"largest-thread-count" => 10,
"max-threads" => 33,
"name" => "default",
"queue-size" => 17,
"rejected-count" => 0,
"task-count" => 182L,
"thread-factory" => undefined
active-count and largest-thread-count are still 10 althought queue-size is 17 and max-threads is 33. After a restart more than 10 threads are started.
Btw. The behavior is the same in EAP 6.0.1.
Regards
Erhard
