Sometimes our nodes won't be able to start new builds even though there are
free slots available.
A workaround for the slaves is to disconnect/connect the slave and it will
start to schedule builds again.
I have observed that when this happens for a slave the slave has fewer threads
ongoing than an idle slave.
Attaching thread dumps when this happens and after doing an
We have seen this issue both on Windows(jlnp) slaves and linux(ssh) slaves as
well as on the master node which is running linux.