To add job priorities, the worker pool underlying the job queue must
support priorities per task. This patch adds them to the worker pool.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

With this patch, the task name is added to the thread name and will show up in
logs. Log messages from jobs will look like “pid=578/JobQueue14/Job13 mcpu:289
DEBUG LU locks acquired/cluster/BGL/shared”.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

By changing it to a normal parameter, which must be a sequence, we can
start using keyword parameters.

Before this patch all arguments to “AddTask(self, *args)” were passed as
arguments to the worker's “RunTask” method. Priorities, which should be
optional and will be implemented in a future patch, must be passed as a keyword
parameter. This means “*args” can no longer be used as one can't combine *args
and keyword parameters in a clean way:

>>> def f(name=None, *args):
...   print "%r, %r" % (args, name)
...
>>> f("p1", "p2", "p3", name="thename")
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 TypeError: f() got multiple values for keyword argument 'name'

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

Each task has to be a sequence, or the RunTask call will fail.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

Currently there's no way to know if something actually gets done.
After this check we actually test that the threads do their job.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

Useful if we want to add many tasks at once, without contention with the
previous one we added starting.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

Having a proper name instead of just a number makes debugging
easier.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

Reviewed-by: ultrotter