最近使用Gunicorn+Flask部署了一套服务，顺便研究下Gunicorn的源码，看看Python 的Prefork模型是如何实现的。具体Gunicorn的用法可以看官方文档，本文直接从源码开始入手。
官方主页：Gunicorn
官方文档：Gunicorn Document
源码版本：gunicorn (version 19.9.0)
源码目录结构：
gunicorn/
├── __init__.py
├── _compat.py
├── app
│ ├── __init__.py
│ ├── base.py
│ ├── pasterapp.py
│ └── wsgiapp.py
├── arbiter.py
├── config.py
├── debug.py
├── errors.py
├── glogging.py
├── http
│ ├── __init__.py
│ ├── body.py
│ ├── errors.py
│ ├── message.py
│ ├── parser.py
│ ├── unreader.py
│ └── wsgi.py
├── instrument
│ ├── __init__.py
│ └── statsd.py
├── pidfile.py
├── reloader.py
├── sock.py
├── systemd.py
├── util.py
└── workers
├── __init__.py
├── _gaiohttp.py
├── base.py
├── base_async.py
├── gaiohttp.py
├── geventlet.py
├── ggevent.py
├── gthread.py
├── gtornado.py
├── sync.py
└── workertmp.py
主要分为4部分
- app
- config
- arbiter
- worker
先从生成配置项的config.py开始。
config.py文件主要是用生成配置对象cfg，为每一个配置项生成一个对象。
class Setting(object):
name = None
value = None
section = None
cli = None
validator = None
type = None
meta = None
action = None
default = None
short = None
desc = None
nargs = None
const = None
def __init__(self):
if self.default is not None:
self.set(self.default)
def add_option(self, parser):
if not self.cli:
return
args = tuple(self.cli)
help_txt = "%s [%s]" % (self.short, self.default)
help_txt = help_txt.replace("%", "%%")
kwargs = {
"dest": self.name,
"action": self.action or "store",
"type": self.type or str,
"default": None,
"help": help_txt
}
if self.meta is not None:
kwargs['metavar'] = self.meta
if kwargs["action"] != "store":
kwargs.pop("type")
if self.nargs is not None:
kwargs["nargs"] = self.nargs
if self.const is not None:
kwargs["const"] = self.const
parser.add_argument(*args, **kwargs)
def copy(self):
return copy.copy(self)
def get(self):
return self.value
def set(self, val):
if not callable(self.validator):
raise TypeError('Invalid validator: %s' % self.name)
self.value = self.validator(val)
def __lt__(self, other):
return (self.section == other.section and
self.order < other.order)
__cmp__ = __lt__
Setting = SettingMeta('Setting', (Setting,), {})
首先看Setting这个类，其中主要定义了模块ArgumentParser解析命令行参数需要的信息，其他如属性value是解析出来的值，属性validator是检查函数。（文件中定义了许多以validate_开头的函数，用来针对不同的配置项，不再赘述）
Setting = SettingMeta('Setting', (Setting,), {})将Setting的元类设置为SettingMeta，表明Setting这个类及其子类都是由SettingMeta创建出来的。
再来看看SettingMeta。
KNOWN_SETTINGS = []
class SettingMeta(type):
def __new__(cls, name, bases, attrs):
super_new = super(SettingMeta, cls).__new__
parents = [b for b in bases if isinstance(b, SettingMeta)]
if not parents:
return super_new(cls, name, bases, attrs)
attrs["order"] = len(KNOWN_SETTINGS)
attrs["validator"] = staticmethod(attrs["validator"])
new_class = super_new(cls, name, bases, attrs)
new_class.fmt_desc(attrs.get("desc", ""))
KNOWN_SETTINGS.append(new_class)
return new_class
def fmt_desc(cls, desc):
desc = textwrap.dedent(desc).strip()
setattr(cls, "desc", desc)
setattr(cls, "short", desc.splitlines()[0])
文件定义了KNOWN_SETTINGS列表，每个继承Setting的类（Setting本身除外）都会被添加到该属性，并且该元类还做了额外的工作，如为每个配置生成序号，将每个validator设置为static方法。
看下其中的一个配置类Bind：
class Bind(Setting):
name = "bind"
action = "append"
section = "Server Socket"
cli = ["-b", "--bind"]
meta = "ADDRESS"
validator = validate_list_string
if 'PORT' in os.environ:
default = ['0.0.0.0:{0}'.format(os.environ.get('PORT'))]
else:
default = ['127.0.0.1:8000']
desc = """\
The socket to bind.
A string of the form: ``HOST``, ``HOST:PORT``, ``unix:PATH``. An IP is
a valid ``HOST``.
Multiple addresses can be bound. ex.::
$ gunicorn -b 127.0.0.1:8000 -b [::1]:8000 test:app
will bind the `test:app` application on localhost both on ipv6
and ipv4 interfaces.
"""
每一个配置类都像上面这样的形式定义，十分简洁。
def make_settings(ignore=None):
settings = {}
ignore = ignore or ()
for s in KNOWN_SETTINGS:
setting = s()
if setting.name in ignore:
continue
settings[setting.name] = setting.copy()
return settings
make_setting方法会将所有定义的Setting子类实例化。
class Config(object):
def __init__(self, usage=None, prog=None):
self.settings = make_settings()
self.usage = usage
self.prog = prog or os.path.basename(sys.argv[0])
self.env_orig = os.environ.copy()
def __getattr__(self, name):
if name not in self.settings:
raise AttributeError("No configuration setting for: %s" % name)
return self.settings[name].get()
def __setattr__(self, name, value):
if name != "settings" and name in self.settings:
raise AttributeError("Invalid access!")
super(Config, self).__setattr__(name, value)
def set(self, name, value):
if name not in self.settings:
raise AttributeError("No configuration setting for: %s" % name)
self.settings[name].set(value)
def get_cmd_args_from_env(self):
if 'GUNICORN_CMD_ARGS' in self.env_orig:
return shlex.split(self.env_orig['GUNICORN_CMD_ARGS'])
return []
def parser(self):
kwargs = {
"usage": self.usage,
"prog": self.prog
}
parser = argparse.ArgumentParser(**kwargs)
parser.add_argument("-v", "--version",
action="version", default=argparse.SUPPRESS,
version="%(prog)s (version " + __version__ + ")\n",
help="show program's version number and exit")
parser.add_argument("args", nargs="*", help=argparse.SUPPRESS)
keys = sorted(self.settings, key=self.settings.__getitem__)
for k in keys:
self.settings[k].add_option(parser)
return parser
@property
def worker_class_str(self):
"""工作进行使用的模式
Returns:
[type] -- [description]
"""
uri = self.settings['worker_class'].get()
## are we using a threaded worker?
is_sync = uri.endswith('SyncWorker') or uri == 'sync'
if is_sync and self.threads > 1:
return "threads" # 如果定义的threads配置大于1，将使用 gthread模式
return uri
@property
def worker_class(self):
"""工作进行使用的模式
Returns:
[type] -- [description]
"""
uri = self.settings['worker_class'].get()
## are we using a threaded worker?
is_sync = uri.endswith('SyncWorker') or uri == 'sync'
if is_sync and self.threads > 1:
uri = "gunicorn.workers.gthread.ThreadWorker"
worker_class = util.load_class(uri)
if hasattr(worker_class, "setup"):
worker_class.setup()
return worker_class
@property
def address(self):
s = self.settings['bind'].get()
return [util.parse_address(util.bytes_to_str(bind)) for bind in s]
@property
def uid(self):
return self.settings['user'].get()
@property
def gid(self):
return self.settings['group'].get()
@property
def proc_name(self):
pn = self.settings['proc_name'].get()
if pn is not None:
return pn
else:
return self.settings['default_proc_name'].get()
@property
def logger_class(self):
"""日志类
Returns:
[type] -- [description]
"""
uri = self.settings['logger_class'].get()
if uri == "simple":
# support the default
uri = LoggerClass.default
# if default logger is in use, and statsd is on, automagically switch
# to the statsd logger
if uri == LoggerClass.default:
if 'statsd_host' in self.settings and self.settings['statsd_host'].value is not None:
uri = "gunicorn.instrument.statsd.Statsd"
logger_class = util.load_class(
uri,
default="gunicorn.glogging.Logger",
section="gunicorn.loggers")
if hasattr(logger_class, "install"):
logger_class.install()
return logger_class
@property
def is_ssl(self):
return self.certfile or self.keyfile
@property
def ssl_options(self):
opts = {}
for name, value in self.settings.items():
if value.section == 'SSL':
opts[name] = value.get()
return opts
@property
def env(self):
raw_env = self.settings['raw_env'].get()
env = {}
if not raw_env:
return env
for e in raw_env:
s = util.bytes_to_str(e)
try:
k, v = s.split('=', 1)
except ValueError:
raise RuntimeError("environment setting %r invalid" % s)
env[k] = v
return env
@property
def sendfile(self):
if self.settings['sendfile'].get() is not None:
return False
if 'SENDFILE' in os.environ:
sendfile = os.environ['SENDFILE'].lower()
return sendfile in ['y', '1', 'yes', 'true']
return True
@property
def reuse_port(self):
return self.settings['reuse_port'].get()
@property
def paste_global_conf(self):
raw_global_conf = self.settings['raw_paste_global_conf'].get()
if raw_global_conf is None:
return None
global_conf = {}
for e in raw_global_conf:
s = util.bytes_to_str(e)
try:
k, v = re.split(r'(?Config对象使用了代理模式，用来控制对每个配置项的访问，访问Config对象的属性大部分会代理到对应的Setting子类对象。
Config. parser()函数会返回一个argparse.ArgumentParser对象，用来解析命令行参数。
UML图：
gunicorn.config