Add note about Zerg fds having to be Unix sockets

Options.rst

@@ -2427,6 +2427,7 @@ Chdir to specified directory after apps loading.
 Set lazy mode (load apps in workers instead of master).
 
 This option may have memory usage implications as Copy-on-Write semantics can not be used.
+When ``lazy`` is enabled, only workers will be reloaded by uWSGI's reload signals; the master will remain alive. As such, uWSGI configuration changes are not picked up on reload by the master.
 
 .. _OptionLazyApps:
 
@@ -2436,6 +2437,9 @@ This option may have memory usage implications as Copy-on-Write semantics can no
 
 Load apps in each worker instead of the master.
 
+This option may have memory usage implications as Copy-on-Write semantics can not be used.
+Unlike ``lazy``, this only affects the way applications are loaded, not master's behavior on reload.
+
 .. _OptionCheap:
 
 ``cheap``

Zerg.rst

@@ -22,6 +22,8 @@ Enabling the zerg server
 
 If you want an uWSGI instance to be rushed by zerg, you have to enable the Zerg server. It will be bound to an UNIX socket and will pass uwsgi socket file descriptors to the Zerg workers connecting to it.
 
+.. warning:: The socket must be an UNIX socket because it must be capable of passing through file descriptors. A TCP socket simply will not work.
+
 For security reasons the UNIX socket does not inherit the ``chmod-socket`` option, but will always use the current umask.
 
 If you have filesystem permission issues, on Linux you can use the UNIX sockets in abstract namespace, by prepending an ``@`` to the socket name.

_options/optdefs.py

@@ -385,8 +385,8 @@ def core_options():
     with config.section("Application loading") as s:
         s.o("chdir", str, "chdir to specified directory before apps loading")
         s.o("chdir2", str, "chdir to specified directory after apps loading")
-        s.o("lazy", True, "set lazy mode (load apps in workers instead of master)", help="This option may have memory usage implications as Copy-on-Write semantics can not be used.")
-        s.o("lazy-apps", True, "load apps in each worker instead of the master")
+        s.o("lazy", True, "set lazy mode (load apps in workers instead of master)", help="This option may have memory usage implications as Copy-on-Write semantics can not be used.\nWhen ``lazy`` is enabled, only workers will be reloaded by uWSGI's reload signals; the master will remain alive. As such, uWSGI configuration changes are not picked up on reload by the master.")
+        s.o("lazy-apps", True, "load apps in each worker instead of the master", help="This option may have memory usage implications as Copy-on-Write semantics can not be used.\nUnlike ``lazy``, this only affects the way applications are loaded, not master's behavior on reload.")
         s.o("cheap", True, "set cheap mode (spawn workers only after the first request)")
         s.o("cheaper", int, "set cheaper mode (adaptive process spawning)", help="""This an advanced `cheap` mode. This will only spawn <n> workers on startup and will use various (pluggable) algorithms to implement adaptive process spawning.""")
         s.o("cheaper-initial", int, "set the initial number of processes to spawn in cheaper mode")