Thread states
As per the Java documentation, a thread state. A thread can be in one of the following states:
NEW
A thread that has not yet started is in this state.
RUNNABLE
A thread executing in the Java virtual machine is in this state.
BLOCKED
A thread that is blocked waiting for a monitor lock is in this state.
WAITING
A thread that is waiting indefinitely for another thread to perform a particular action is in this state.
TIMED_WAITING
A thread that is waiting for another thread to perform an action for up to a specified waiting time is in this state.
TERMINATED
A thread that has exited is in this state.
A thread can be in only one state at a given point in time. These states are virtual machine states which do not reflect any operating system thread states.
When a process/worker is simply in an idle wait state
You will see
sun.misc.Unsafe.park(Native Method)
or
java.lang.Object.wait(Native)
In the thread dump