[FIX] server_environment: fix deadlock between gevent and subprocesses

server_environment/server_env.py

@@ -14,7 +14,7 @@
 
 from odoo.addons.base_sparse_field.models.fields import Serialized
 
-from .system_info import get_server_environment
+from .system_info import get_server_environment, skip_subprocess
 
 _logger = logging.getLogger(__name__)
 
@@ -246,6 +246,8 @@ def _get_env_cols(cls, sections=None):
     @classmethod
     def _get_system_cols(cls):
         """Compute system fields"""
+        if skip_subprocess():
+            return {}
         res = {}
         for col, item in get_server_environment():
             key = cls._format_key("system", col)

server_environment/system_info.py

@@ -8,11 +8,25 @@
 import subprocess
 from functools import lru_cache
 
+import odoo
 from odoo import release
 from odoo.tools.config import config
 
 
+def skip_subprocess():
+    # In the gevent worker (longpolling/websocket) running subprocesses can
+    # deadlock, freezing real-time updates. This system info only feeds the
+    # settings display, so skip the subprocess calls there.
+    return odoo.evented
+
+
 def _get_output(cmd):
+    # Use assert to force developers to
+    # take correct action when developing
+    # but running `python -O` removes it completely
+    assert (
+        not skip_subprocess()
+    ), "Subprocess must not be called, use skip_subprocess in a pre-check"
     bindir = config["root_path"]
     p = subprocess.Popen(
         cmd, shell=True, cwd=bindir, stdout=subprocess.PIPE, stderr=subprocess.STDOUT
@@ -22,6 +36,9 @@ def _get_output(cmd):
 
 @lru_cache(maxsize=1)
 def get_server_environment():
+    # Function relies mainly on subprocesses
+    if skip_subprocess():
+        return ()
     # inspired by server/bin/service/web_services.py
     try:
         rev_id = "git:%s" % _get_output("git rev-parse HEAD")