Allow to config the behavior on CTRL+C

By default, we run SIGKILL after 0.5 seconds. Most of the time is
enough. But if the interrupted command have a complex processes tree,
it might not be enough to propagate the signal.

In such case processes are left behind and never killed.
If theses processes use static network port or keep file open. Next
call of tox will fail until the all processes left behind are manually
killed.

This change adds some configuration to be able to config the timeout
before signals are sent.

If the approach work for you, I will polish the PR (doc+test)

Author: sileht

src/tox/action.py

@@ -18,14 +18,12 @@
 from tox.util.lock import get_unique_file
 from tox.util.stdlib import is_main_thread
 
-WAIT_INTERRUPT = 0.3
-WAIT_TERMINATE = 0.2
-
 
 class Action(object):
     """Action is an effort to group operations with the same goal (within reporting)"""
 
-    def __init__(self, name, msg, args, log_dir, generate_tox_log, command_log, popen, python):
+    def __init__(self, name, msg, args, log_dir, generate_tox_log, command_log, popen,
+                 python, interrupt_timeout, terminate_timeout):
         self.name = name
         self.args = args
         self.msg = msg
@@ -36,6 +34,8 @@ def __init__(self, name, msg, args, log_dir, generate_tox_log, command_log, pope
         self.command_log = command_log
         self._timed_report = None
         self.python = python
+        self.interrupt_timeout = interrupt_timeout
+        self.terminate_timeout = terminate_timeout
 
     def __enter__(self):
         msg = "{} {}".format(self.msg, " ".join(map(str, self.args)))
@@ -180,10 +180,10 @@ def handle_interrupt(self, process):
         if process.poll() is None:
             self.info("KeyboardInterrupt", msg.format("SIGINT"))
             process.send_signal(signal.CTRL_C_EVENT if sys.platform == "win32" else signal.SIGINT)
-            if self._wait(process, WAIT_INTERRUPT) is None:
+            if self._wait(process, self.interrupt_timeout) is None:
                 self.info("KeyboardInterrupt", msg.format("SIGTERM"))
                 process.terminate()
-                if self._wait(process, WAIT_TERMINATE) is None:
+                if self._wait(process, self.terminate_timeout) is None:
                     self.info("KeyboardInterrupt", msg.format("SIGKILL"))
                     process.kill()
                     process.communicate()
@@ -193,7 +193,7 @@ def _wait(process, timeout):
         if sys.version_info >= (3, 3):
             # python 3 has timeout feature built-in
             try:
-                process.communicate(timeout=WAIT_INTERRUPT)
+                process.communicate(timeout=timeout)
             except subprocess.TimeoutExpired:
                 pass
         else:

src/tox/config/__init__.py

@@ -798,6 +798,20 @@ def develop(testenv_config, value):
 
     parser.add_testenv_attribute_obj(DepOption())
 
+    parser.add_testenv_attribute(
+        name="interrupt_timeout",
+        type="float",
+        default=0.3,
+        help="timeout before sending SIGTERM after SIGINT",
+    )
+
+    parser.add_testenv_attribute(
+        name="terminate_timeout",
+        type="float",
+        default=0.2,
+        help="timeout before sending SIGKILL after SIGTERM",
+    )
+
     parser.add_testenv_attribute(
         name="commands",
         type="argvlist",
@@ -1231,7 +1245,8 @@ def make_envconfig(self, name, section, subs, config, replace=True):
         for env_attr in config._testenv_attr:
             atype = env_attr.type
             try:
-                if atype in ("bool", "path", "string", "dict", "dict_setenv", "argv", "argvlist"):
+                if atype in ("bool", "float", "path", "string",
+                             "dict", "dict_setenv", "argv", "argvlist"):
                     meth = getattr(reader, "get{}".format(atype))
                     res = meth(env_attr.name, env_attr.default, replace=replace)
                 elif atype == "basepython":
@@ -1448,6 +1463,22 @@ def _getdict(self, value, default, sep, replace=True):
 
         return d
 
+    def getfloat(self, name, default=None, replace=True):
+        s = self.getstring(name, default, replace=replace)
+        if not s or not replace:
+            s = default
+        if s is None:
+            raise KeyError("no config value [{}] {} found".format(self.section_name, name))
+
+        if not isinstance(s, float):
+            try:
+                s = float(s)
+            except ValueError:
+                raise tox.exception.ConfigError(
+                    "{}: invalid float {!r}".format(name, s)
+                )
+        return s
+
     def getbool(self, name, default=None, replace=True):
         s = self.getstring(name, default, replace=replace)
         if not s or not replace:

src/tox/session/__init__.py

@@ -37,6 +37,9 @@
 from .commands.show_config import show_config
 from .commands.show_env import show_envs
 
+WAIT_INTERRUPT = 0.3
+WAIT_TERMINATE = 0.2
+
 
 def cmdline(args=None):
     if args is None:
@@ -170,6 +173,8 @@ def newaction(self, name, msg, *args):
             self.resultlog.command_log,
             self.popen,
             sys.executable,
+            WAIT_INTERRUPT,
+            WAIT_TERMINATE,
         )
 
     def runcommand(self):

src/tox/venv.py

@@ -130,6 +130,8 @@ def new_action(self, msg, *args):
             command_log,
             self.popen,
             self.envconfig.envpython,
+            self.envconfig.interrupt_timeout,
+            self.envconfig.terminate_timeout,
         )
 
     def get_result_json_path(self):