Add post_spawn signal. (#93)

Co-authored-by: David Hoover <hooverd@arizona.edu>

django_q/cluster.py

@@ -39,7 +39,7 @@ from django_q.conf import (
 from django_q.humanhash import humanize
 from django_q.models import Schedule, Success, Task
 from django_q.queues import Queue
-from django_q.signals import post_execute, pre_execute
+from django_q.signals import post_execute, post_spawn, pre_execute
 from django_q.signing import BadSignature, SignedPackage
 from django_q.status import Stat, Status
 
@@ -481,6 +481,7 @@ def worker(
         _("%(proc_name)s ready for work at %(id)s")
         % {"proc_name": proc_name, "id": current_process().pid}
     )
+    post_spawn.send(sender="django_q", proc_name=proc_name)
     if setproctitle:
         setproctitle.setproctitle(f"qcluster {proc_name} idle")
     task_count = 0

django_q/signals.py

@@ -31,6 +31,8 @@ def call_hook(sender, instance, **kwargs):
                 % {"hook": instance.hook, "name": instance.name, "error": str(e)}
             )
 
+# args: proc_name
+post_spawn = Signal()
 
 # args: task
 pre_enqueue = Signal()