--threadless default for Python 3.8+ on mac and linux

README.md

@@ -1603,16 +1603,19 @@ Now point your CDT instance to `ws://localhost:8899/devtools`.
 
 ## Threads vs Threadless
 
-Pre v2.x, `proxy.py` used to spawn new threads for handling
-client requests.
+### Pre v2.x
 
-Starting v2.x, `proxy.py` added support for threadless execution of
-client requests using `asyncio`.
+`proxy.py` used to spawn new threads for handling client requests.
 
-In future, threadless execution will be the default mode.
+### Starting v2.0
 
-Till then if you are interested in trying it out,
-start `proxy.py` with `--threadless` flag.
+`proxy.py` added support for threadless execution of client requests using `asyncio`.
+
+### Starting v2.4.0
+
+Threadless execution was turned ON by default for `Python 3.8+` on `mac` and `linux` environments.  `proxy.py` threadless execution has been reported safe on these environments by our users.  If you are running into trouble, fallback to threaded mode using `--threaded` flag.
+
+For `windows` and `Python < 3.8`, you can still try out threadless mode by starting `proxy.py` with `--threadless` flag.  If threadless works for you, consider sending a PR by editing `_env_threadless_compliant` method in the `proxy/common/constants.py` file.
 
 ## SyntaxError: invalid syntax
 
@@ -1883,19 +1886,23 @@ for list of tests.
 
 ```console
 ❯ proxy -h
-usage: proxy [-h] [--enable-events] [--enable-conn-pool] [--threadless] [--pid-file PID_FILE]
-          [--backlog BACKLOG] [--hostname HOSTNAME] [--port PORT] [--num-workers NUM_WORKERS]
-          [--unix-socket-path UNIX_SOCKET_PATH] [--client-recvbuf-size CLIENT_RECVBUF_SIZE]
-          [--key-file KEY_FILE] [--timeout TIMEOUT] [--version] [--log-level LOG_LEVEL]
-          [--log-file LOG_FILE] [--log-format LOG_FORMAT] [--open-file-limit OPEN_FILE_LIMIT]
-          [--plugins PLUGINS] [--disable-http-proxy] [--ca-key-file CA_KEY_FILE]
-          [--ca-cert-dir CA_CERT_DIR] [--ca-cert-file CA_CERT_FILE] [--ca-file CA_FILE]
-          [--ca-signing-key-file CA_SIGNING_KEY_FILE] [--cert-file CERT_FILE]
-          [--disable-headers DISABLE_HEADERS] [--server-recvbuf-size SERVER_RECVBUF_SIZE]
-          [--basic-auth BASIC_AUTH] [--cache-dir CACHE_DIR]
-          [--filtered-upstream-hosts FILTERED_UPSTREAM_HOSTS] [--enable-web-server]
-          [--enable-static-server] [--static-server-dir STATIC_SERVER_DIR]
-          [--pac-file PAC_FILE] [--pac-file-url-path PAC_FILE_URL_PATH]
+usage: proxy [-h] [--enable-events] [--enable-conn-pool] [--threadless] [--threaded]
+          [--pid-file PID_FILE] [--backlog BACKLOG] [--hostname HOSTNAME]
+          [--port PORT] [--num-workers NUM_WORKERS]
+          [--unix-socket-path UNIX_SOCKET_PATH]
+          [--client-recvbuf-size CLIENT_RECVBUF_SIZE] [--key-file KEY_FILE]
+          [--timeout TIMEOUT] [--version] [--log-level LOG_LEVEL]
+          [--log-file LOG_FILE] [--log-format LOG_FORMAT]
+          [--open-file-limit OPEN_FILE_LIMIT] [--plugins PLUGINS] [--enable-dashboard]
+          [--disable-http-proxy] [--ca-key-file CA_KEY_FILE]
+          [--ca-cert-dir CA_CERT_DIR] [--ca-cert-file CA_CERT_FILE]
+          [--ca-file CA_FILE] [--ca-signing-key-file CA_SIGNING_KEY_FILE]
+          [--cert-file CERT_FILE] [--disable-headers DISABLE_HEADERS]
+          [--server-recvbuf-size SERVER_RECVBUF_SIZE] [--basic-auth BASIC_AUTH]
+          [--cache-dir CACHE_DIR] [--filtered-upstream-hosts FILTERED_UPSTREAM_HOSTS]
+          [--enable-web-server] [--enable-static-server]
+          [--static-server-dir STATIC_SERVER_DIR] [--pac-file PAC_FILE]
+          [--pac-file-url-path PAC_FILE_URL_PATH]
           [--filtered-client-ips FILTERED_CLIENT_IPS]
           [--filtered-url-regex-config FILTERED_URL_REGEX_CONFIG]
           [--cloudflare-dns-mode CLOUDFLARE_DNS_MODE]
@@ -1904,104 +1911,111 @@ proxy.py v2.4.0
 
 options:
   -h, --help            show this help message and exit
-  --enable-events       Default: False. Enables core to dispatch lifecycle events. Plugins
-                        can be used to subscribe for core events.
+  --enable-events       Default: False. Enables core to dispatch lifecycle events.
+                        Plugins can be used to subscribe for core events.
   --enable-conn-pool    Default: False. (WIP) Enable upstream connection pooling.
-  --threadless          Default: False. When disabled a new thread is spawned to handle each
+  --threadless          Default: True. Enabled by default on Python 3.8+ (mac, linux).
+                        When disabled a new thread is spawned to handle each client
+                        connection.
+  --threaded            Default: False. Disabled by default on Python < 3.8 and
+                        windows. When enabled a new thread is spawned to handle each
                         client connection.
   --pid-file PID_FILE   Default: None. Save parent process ID to a file.
-  --backlog BACKLOG     Default: 100. Maximum number of pending connections to proxy server
+  --backlog BACKLOG     Default: 100. Maximum number of pending connections to proxy
+                        server
   --hostname HOSTNAME   Default: ::1. Server IP address.
   --port PORT           Default: 8899. Server port.
   --num-workers NUM_WORKERS
                         Defaults to number of CPU cores.
   --unix-socket-path UNIX_SOCKET_PATH
-                        Default: None. Unix socket path to use. When provided --host and
-                        --port flags are ignored
+                        Default: None. Unix socket path to use. When provided --host
+                        and --port flags are ignored
   --client-recvbuf-size CLIENT_RECVBUF_SIZE
-                        Default: 1 MB. Maximum amount of data received from the client in a
-                        single recv() operation. Bump this value for faster uploads at the
-                        expense of increased RAM.
-  --key-file KEY_FILE   Default: None. Server key file to enable end-to-end TLS encryption
-                        with clients. If used, must also pass --cert-file.
-  --timeout TIMEOUT     Default: 10.0. Number of seconds after which an inactive connection
-                        must be dropped. Inactivity is defined by no data sent or received by
-                        the client.
+                        Default: 1 MB. Maximum amount of data received from the client
+                        in a single recv() operation. Bump this value for faster
+                        uploads at the expense of increased RAM.
+  --key-file KEY_FILE   Default: None. Server key file to enable end-to-end TLS
+                        encryption with clients. If used, must also pass --cert-file.
+  --timeout TIMEOUT     Default: 10.0. Number of seconds after which an inactive
+                        connection must be dropped. Inactivity is defined by no data
+                        sent or received by the client.
   --version, -v         Prints proxy.py version.
   --log-level LOG_LEVEL
-                        Valid options: DEBUG, INFO (default), WARNING, ERROR, CRITICAL. Both
-                        upper and lowercase values are allowed. You may also simply use the
-                        leading character e.g. --log-level d
+                        Valid options: DEBUG, INFO (default), WARNING, ERROR,
+                        CRITICAL. Both upper and lowercase values are allowed. You may
+                        also simply use the leading character e.g. --log-level d
   --log-file LOG_FILE   Default: sys.stdout. Log file destination.
   --log-format LOG_FORMAT
                         Log format for Python logger.
   --open-file-limit OPEN_FILE_LIMIT
                         Default: 1024. Maximum number of files (TCP connections) that
                         proxy.py can open concurrently.
   --plugins PLUGINS     Comma separated plugins
+  --enable-dashboard    Default: False. Enables proxy.py dashboard.
   --disable-http-proxy  Default: False. Whether to disable proxy.HttpProxyPlugin.
   --ca-key-file CA_KEY_FILE
-                        Default: None. CA key to use for signing dynamically generated HTTPS
-                        certificates. If used, must also pass --ca-cert-file and --ca-
-                        signing-key-file
+                        Default: None. CA key to use for signing dynamically generated
+                        HTTPS certificates. If used, must also pass --ca-cert-file and
+                        --ca-signing-key-file
   --ca-cert-dir CA_CERT_DIR
                         Default: ~/.proxy.py. Directory to store dynamically generated
                         certificates. Also see --ca-key-file, --ca-cert-file and --ca-
                         signing-key-file
   --ca-cert-file CA_CERT_FILE
-                        Default: None. Signing certificate to use for signing dynamically
-                        generated HTTPS certificates. If used, must also pass --ca-key-file
-                        and --ca-signing-key-file
+                        Default: None. Signing certificate to use for signing
+                        dynamically generated HTTPS certificates. If used, must also
+                        pass --ca-key-file and --ca-signing-key-file
   --ca-file CA_FILE     Default:
                         /Users/abhinavsingh/Dev/proxy.py/venv310/lib/python3.10/site-
-                        packages/certifi/cacert.pem. Provide path to custom CA bundle for
-                        peer certificate verification
+                        packages/certifi/cacert.pem. Provide path to custom CA bundle
+                        for peer certificate verification
   --ca-signing-key-file CA_SIGNING_KEY_FILE
-                        Default: None. CA signing key to use for dynamic generation of HTTPS
-                        certificates. If used, must also pass --ca-key-file and --ca-cert-
-                        file
+                        Default: None. CA signing key to use for dynamic generation of
+                        HTTPS certificates. If used, must also pass --ca-key-file and
+                        --ca-cert-file
   --cert-file CERT_FILE
-                        Default: None. Server certificate to enable end-to-end TLS encryption
-                        with clients. If used, must also pass --key-file.
+                        Default: None. Server certificate to enable end-to-end TLS
+                        encryption with clients. If used, must also pass --key-file.
   --disable-headers DISABLE_HEADERS
-                        Default: None. Comma separated list of headers to remove before
-                        dispatching client request to upstream server.
+                        Default: None. Comma separated list of headers to remove
+                        before dispatching client request to upstream server.
   --server-recvbuf-size SERVER_RECVBUF_SIZE
-                        Default: 1 MB. Maximum amount of data received from the server in a
-                        single recv() operation. Bump this value for faster downloads at the
-                        expense of increased RAM.
+                        Default: 1 MB. Maximum amount of data received from the server
+                        in a single recv() operation. Bump this value for faster
+                        downloads at the expense of increased RAM.
   --basic-auth BASIC_AUTH
-                        Default: No authentication. Specify colon separated user:password to
-                        enable basic authentication.
+                        Default: No authentication. Specify colon separated
+                        user:password to enable basic authentication.
   --cache-dir CACHE_DIR
-                        Default: A temporary directory. Flag only applicable when cache
-                        plugin is used with on-disk storage.
+                        Default: A temporary directory. Flag only applicable when
+                        cache plugin is used with on-disk storage.
   --filtered-upstream-hosts FILTERED_UPSTREAM_HOSTS
-                        Default: Blocks Facebook. Comma separated list of IPv4 and IPv6
-                        addresses.
+                        Default: Blocks Facebook. Comma separated list of IPv4 and
+                        IPv6 addresses.
   --enable-web-server   Default: False. Whether to enable proxy.HttpWebServerPlugin.
   --enable-static-server
-                        Default: False. Enable inbuilt static file server. Optionally, also
-                        use --static-server-dir to serve static content from custom
-                        directory. By default, static file server serves out of installed
-                        proxy.py python module folder.
+                        Default: False. Enable inbuilt static file server. Optionally,
+                        also use --static-server-dir to serve static content from
+                        custom directory. By default, static file server serves out of
+                        installed proxy.py python module folder.
   --static-server-dir STATIC_SERVER_DIR
-                        Default: "public" folder in directory where proxy.py is placed. This
-                        option is only applicable when static server is also enabled. See
-                        --enable-static-server.
-  --pac-file PAC_FILE   A file (Proxy Auto Configuration) or string to serve when the server
-                        receives a direct file request. Using this option enables
-                        proxy.HttpWebServerPlugin.
+                        Default: "public" folder in directory where proxy.py is
+                        placed. This option is only applicable when static server is
+                        also enabled. See --enable-static-server.
+  --pac-file PAC_FILE   A file (Proxy Auto Configuration) or string to serve when the
+                        server receives a direct file request. Using this option
+                        enables proxy.HttpWebServerPlugin.
   --pac-file-url-path PAC_FILE_URL_PATH
                         Default: /. Web server path to serve the PAC file.
   --filtered-client-ips FILTERED_CLIENT_IPS
                         Default: 127.0.0.1,::1. Comma separated list of IPv4 and IPv6
                         addresses.
   --filtered-url-regex-config FILTERED_URL_REGEX_CONFIG
-                        Default: No config. Comma separated list of IPv4 and IPv6 addresses.
+                        Default: No config. Comma separated list of IPv4 and IPv6
+                        addresses.
   --cloudflare-dns-mode CLOUDFLARE_DNS_MODE
-                        Default: security. Either "security" (for malware protection) or
-                        "family" (for malware and adult content protection)
+                        Default: security. Either "security" (for malware protection)
+                        or "family" (for malware and adult content protection)
 
 Proxy.py not working? Report at: https://github.com/abhinavsingh/proxy.py/issues/new
 ```

proxy/common/constants.py

@@ -9,6 +9,7 @@
     :license: BSD, see LICENSE for more details.
 """
 import os
+import sys
 import time
 import secrets
 import pathlib
@@ -19,6 +20,15 @@
 
 from .version import __version__
 
+
+def _env_threadless_compliant() -> bool:
+    """Returns true for Python 3.8+ across all platforms
+    except Windows."""
+    if os.name == 'nt':
+        return False
+    return sys.version_info >= (3, 8)
+
+
 PROXY_PY_START_TIME = time.time()
 
 # /path/to/proxy.py/proxy folder
@@ -86,7 +96,7 @@
 DEFAULT_PORT = 8899
 DEFAULT_SERVER_RECVBUF_SIZE = DEFAULT_BUFFER_SIZE
 DEFAULT_STATIC_SERVER_DIR = os.path.join(PROXY_PY_DIR, "public")
-DEFAULT_THREADLESS = False
+DEFAULT_THREADLESS = _env_threadless_compliant()
 DEFAULT_TIMEOUT = 10.0
 DEFAULT_VERSION = False
 DEFAULT_HTTP_PORT = 80

proxy/common/flag.py

@@ -270,6 +270,7 @@ def initialize(
         )
         args.timeout = cast(int, opts.get('timeout', args.timeout))
         args.threadless = cast(bool, opts.get('threadless', args.threadless))
+        args.threaded = cast(bool, opts.get('threaded', args.threaded))
         args.enable_events = cast(
             bool,
             opts.get(

proxy/common/utils.py

@@ -20,17 +20,26 @@
 from types import TracebackType
 from typing import Optional, Dict, Any, List, Tuple, Type, Callable
 
-from .constants import HTTP_1_1, COLON, WHITESPACE, CRLF, DEFAULT_TIMEOUT
+from .constants import HTTP_1_1, COLON, WHITESPACE, CRLF, DEFAULT_TIMEOUT, DEFAULT_THREADLESS
 
 if os.name != 'nt':
     import resource
 
 logger = logging.getLogger(__name__)
 
 
+def is_threadless(threadless: bool, threaded: bool) -> bool:
+    # if default is threadless then return true unless
+    # user has overridden mode using threaded flag.
+    #
+    # if default is not threadless then return true
+    # only if user has overridden using --threadless flag
+    return (DEFAULT_THREADLESS and not threaded) or (not DEFAULT_THREADLESS and threadless)
+
+
 def is_py2() -> bool:
     """Exists only to avoid mocking sys.version_info in tests."""
-    return sys.version_info[0] == 2
+    return sys.version_info.major == 2
 
 
 def text_(s: Any, encoding: str = 'utf-8', errors: str = 'strict') -> Any:

proxy/core/acceptor/acceptor.py

@@ -27,6 +27,7 @@
 from ..event import EventQueue, eventNames
 from ...common.constants import DEFAULT_THREADLESS
 from ...common.flag import flags
+from ...common.utils import is_threadless
 from ...common.logger import Logger
 
 logger = logging.getLogger(__name__)
@@ -36,7 +37,19 @@
     '--threadless',
     action='store_true',
     default=DEFAULT_THREADLESS,
-    help='Default: False.  When disabled a new thread is spawned '
+    help='Default: ' + ('True' if DEFAULT_THREADLESS else 'False') + '.  ' +
+    'Enabled by default on Python 3.8+ (mac, linux).  ' +
+    'When disabled a new thread is spawned '
+    'to handle each client connection.',
+)
+
+flags.add_argument(
+    '--threaded',
+    action='store_true',
+    default=not DEFAULT_THREADLESS,
+    help='Default: ' + ('True' if not DEFAULT_THREADLESS else 'False') + '.  ' +
+    'Disabled by default on Python < 3.8 and windows.  ' +
+    'When enabled a new thread is spawned '
     'to handle each client connection.',
 )
 
@@ -150,7 +163,7 @@ def run_once(self) -> None:
             conn, addr = self.sock.accept()
         addr = None if addr == '' else addr
         if (
-                self.flags.threadless and
+                is_threadless(self.flags.threadless, self.flags.threaded) and
                 self.threadless_client_queue and
                 self.threadless_process
         ):
@@ -173,15 +186,15 @@ def run(self) -> None:
         )
         try:
             self.selector.register(self.sock, selectors.EVENT_READ)
-            if self.flags.threadless:
+            if is_threadless(self.flags.threadless, self.flags.threaded):
                 self.start_threadless_process()
             while not self.running.is_set():
                 self.run_once()
         except KeyboardInterrupt:
             pass
         finally:
             self.selector.unregister(self.sock)
-            if self.flags.threadless:
+            if is_threadless(self.flags.threadless, self.flags.threaded):
                 self.shutdown_threadless_process()
             self.sock.close()
             logger.debug('Acceptor#%d shutdown', self.idd)

proxy/core/event/manager.py

@@ -75,10 +75,10 @@ def setup(self) -> None:
         logger.debug('Thread ID: %d', self.dispatcher_thread.ident)
 
     def shutdown(self) -> None:
-        assert self.dispatcher_shutdown
-        assert self.dispatcher_thread
+        assert self.dispatcher_shutdown and self.dispatcher_thread and self.manager
         self.dispatcher_shutdown.set()
         self.dispatcher_thread.join()
+        self.manager.shutdown()
         logger.debug(
             'Shutdown of global event dispatcher thread %d successful',
             self.dispatcher_thread.ident,