Added THREAD_SUBPROCS env var

tests/test_builtins.py

@@ -6,6 +6,7 @@ import re
 import builtins
 import types
 from ast import AST, Module, Interactive, Expression
+from subprocess import Popen
 
 import pytest
 
@@ -25,8 +26,10 @@ from xonsh.built_ins import (
     in_macro_call,
     call_macro,
     enter_macro,
+    cmds_to_specs,
 )
 from xonsh.environ import Env
+from xonsh.proc import PopenThread, ProcProxy, ProcProxyThread
 
 from tools import skip_if_on_windows
 
@@ -388,3 +391,28 @@ def test_enter_macro():
     assert obj.macro_block == "wakka"
     assert obj.macro_globals
     assert obj.macro_locals
+
+
+@skip_if_on_windows
+def test_cmds_to_specs_thread_subproc(xonsh_builtins):
+    env = xonsh_builtins.__xonsh__.env
+    cmds = [["pwd"]]
+    # First check that threadable subprocs become threadable
+    env['THREAD_SUBPROCS'] = True
+    specs = cmds_to_specs(cmds, captured='hiddenobject')
+    assert specs[0].cls is PopenThread
+    # turn off threading and check we use Popen
+    env['THREAD_SUBPROCS'] = False
+    specs = cmds_to_specs(cmds, captured='hiddenobject')
+    assert specs[0].cls is Popen
+
+    # now check the threadbility of callable aliases
+    cmds = [[lambda: "Keras Selyrian"]]
+    # check that threadable alias become threadable
+    env['THREAD_SUBPROCS'] = True
+    specs = cmds_to_specs(cmds, captured='hiddenobject')
+    assert specs[0].cls is ProcProxyThread
+    # turn off threading and check we use ProcProxy
+    env['THREAD_SUBPROCS'] = False
+    specs = cmds_to_specs(cmds, captured='hiddenobject')
+    assert specs[0].cls is ProcProxy

xonsh/built_ins.py

@@ -738,7 +738,8 @@ class SubprocSpec:
         if not callable(alias):
             return
         self.is_proxy = True
-        thable = getattr(alias, "__xonsh_threadable__", True)
+        env = builtins.__xonsh__.env
+        thable = env.get('THREAD_SUBPROCS') and getattr(alias, "__xonsh_threadable__", True)
         cls = ProcProxyThread if thable else ProcProxy
         self.cls = cls
         self.threadable = thable
@@ -790,6 +791,7 @@ def _safe_pipe_properties(fd, use_tty=False):
 
 
 def _update_last_spec(last):
+    env = builtins.__xonsh__.env
     captured = last.captured
     last.last_in_pipeline = True
     if not captured:
@@ -799,7 +801,7 @@ def _update_last_spec(last):
         pass
     else:
         cmds_cache = builtins.__xonsh__.commands_cache
-        thable = cmds_cache.predict_threadable(
+        thable = env.get('THREAD_SUBPROCS') and cmds_cache.predict_threadable(
             last.args
         ) and cmds_cache.predict_threadable(last.cmd)
         if captured and thable:

xonsh/environ.py

@@ -571,6 +571,7 @@ def DEFAULT_ENSURERS():
         "SUGGEST_MAX_NUM": (is_int, int, str),
         "SUGGEST_THRESHOLD": (is_int, int, str),
         "SUPPRESS_BRANCH_TIMEOUT_MESSAGE": (is_bool, to_bool, bool_to_str),
+        "THREAD_SUBPROCS": (is_bool, to_bool, bool_to_str),
         "UPDATE_COMPLETIONS_ON_KEYPRESS": (is_bool, to_bool, bool_to_str),
         "UPDATE_OS_ENVIRON": (is_bool, to_bool, bool_to_str),
         "UPDATE_PROMPT_ON_KEYPRESS": (is_bool, to_bool, bool_to_str),
@@ -755,6 +756,7 @@ def DEFAULT_VALUES():
         "SUGGEST_COMMANDS": True,
         "SUGGEST_MAX_NUM": 5,
         "SUGGEST_THRESHOLD": 3,
+        "THREAD_SUBPROCS": True,
         "TITLE": DEFAULT_TITLE,
         "UPDATE_COMPLETIONS_ON_KEYPRESS": False,
         "UPDATE_OS_ENVIRON": False,
@@ -1159,6 +1161,26 @@ def DEFAULT_DOCS():
             "not always happen.",
             configurable=False,
         ),
+        "THREAD_SUBPROCS": VarDocs(
+            "Whether or not to try to run subrocess mode in a Python thread, "
+            "when applicable. There are various trade-offs, which normally "
+            "affects only interactive sessions.\n\nWhen True:\n\n"
+            "* Xonsh is able capture & store the stdin, stdout, and stderr \n"
+            "  of threadable subprocesses.\n"
+            "* However, stopping threaded suprocs with ^Z (i.e. ``SIGTSTP``)\n"
+            "  is disabled as it causes deadlocked terminals.\n"
+            "  ``SIGTSTP`` may still be issued and only the physical pressing\n"
+            "  of ``Ctrl+Z`` is ignored.\n"
+            "* Thredable commands are run with ``PopenThread`` and threadable \n"
+            "  alias are run with ``ProcProxyThread``.\n\n"
+            "When False:\n\n"
+            "* Xonsh may not be able to capture stdin, stdout, and stderr streams \n"
+            "  unless explicitly asked to do so.\n"
+            "* Stopping the thread with yields to job control.\n"
+            "* Thredable commands are run with ``Popen`` and threadable \n"
+            "  alias are run with ``ProcProxy``.\n\n"
+            "The desired effect is often up to the command, user, or use case."
+        ),
         "TITLE": VarDocs(
             "The title text for the window in which xonsh is running. Formatted "
             "in the same manner as ``$PROMPT``, see 'Customizing the Prompt' "

xontrib/bashisms.py

@@ -2,6 +2,7 @@
 import shlex
 import sys
 import re
+import builtins
 
 
 __all__ = ()
@@ -62,3 +63,4 @@ def alias(args, stdin=None):
 
 
 aliases["alias"] = alias
+builtins.__xonsh__.env['THREAD_SUBPROCS'] = False