process_count_max: add defaults and documentation

conf/minion

@@ -689,6 +689,12 @@
 # for a full explanation.
 #multiprocessing: True
 
+# Limit the maximum amount of processes or threads created by salt-minion.
+# This is useful to avoid resource exhaustion in case the minion receives more
+# publications than it is able to handle, as it limits the number of spawned
+# processes or threads. -1 disables the limit.
+#process_count_max: 20
+
 
 #####         Logging settings       #####
 ##########################################

doc/ref/configuration/minion.rst

@@ -2419,6 +2419,23 @@ executed in a thread.
 
     multiprocessing: True
 
+.. conf_minion:: process_count_max
+
+``process_count_max``
+-------
+
+.. versionadded:: Oxygen
+
+Default: ``20``
+
+Limit the maximum amount of processes or threads created by ``salt-minion``.
+This is useful to avoid resource exhaustion in case the minion receives more
+publications than it is able to handle, as it limits the number of spawned
+processes or threads. ``-1`` disables the limit.
+
+.. code-block:: yaml
+
+    process_count_max: 20
 
 .. _minion-logging-settings:
 

salt/config/__init__.py

@@ -337,6 +337,9 @@ VALID_OPTS = {
     # Whether or not processes should be forked when needed. The alternative is to use threading.
     'multiprocessing': bool,
 
+    # Maximum number of concurrently active processes at any given point in time
+    'process_count_max': int,
+
     # Whether or not the salt minion should run scheduled mine updates
     'mine_enabled': bool,
 
@@ -1258,6 +1261,7 @@ DEFAULT_MINION_OPTS = {
     'auto_accept': True,
     'autosign_timeout': 120,
     'multiprocessing': True,
+    'process_count_max': 20,
     'mine_enabled': True,
     'mine_return_job': False,
     'mine_interval': 60,