When using the plugin with a list of label slave (slave1, slave2, slave) as follow:

node ('slave1||slave2||slave3')

It only show a log when waiting a long time (1 hour) if these slave are busy:
Still waiting to schedule task
Waiting for next available executor on 'slave1||slave2||slave3'

I think it should improve to show more log like  may be show a friendly message log to notify user like "NO NODE IS FREE TO TAKE THE JOB, RETRYING INTERNALLY, WILL PUBLISH NEXT STATUS IN 3 MIN" and show slaves status every 3 minutes:

14:09:08 Still waiting to schedule task
14:09:08
14:09:08 =========The current candidate slave list status for this pipeline========
14:09:08 Waiting for next available executor on slave1||slave2||slave3
14:09:08 slave1 is busy !!!
14:09:08 slave2 is busy !!!
14:09:08 slave3 is busy !!!
14:09:08 **** NO NODE IS FREE TO TAKE THE JOB, RETRYING INTERNALLY, WILL PUBLISH NEXT STATUS IN 3 MIN ****
14:12:08
14:12:08 =========The current candidate slave list status for this pipeline========
14:12:08 slave1 is busy !!!
14:12:08 slave2 is busy !!!
14:12:08 slave3 is busy !!!
14:12:08 **** NO NODE IS FREE TO TAKE THE JOB, RETRYING INTERNALLY, WILL PUBLISH NEXT STATUS IN 3 MIN ****
...
...
14:54:08
14:54:08 =========The current candidate slave list status for this pipeline========
14:54:08 slave1 is busy !!!
14:54:08 slave2 is busy !!!
14:54:08 slave3 is busy !!!
14:54:08 **** NO NODE IS FREE TO TAKE THE JOB, RETRYING INTERNALLY, WILL PUBLISH NEXT STATUS IN 3 MIN ****
14:54:21 Running on slave1 in /home/jenkins/workspace/TestSlaveAlocation2