标签:call iat red 可迭代对象 exception occurs else current none
grequests实际上就是封装了gevent里面的方法,然后配合上requests模块实现了异步的IO
grequests = gevent + requests + greenlet
grequests.map()内部的实现
def map(requests, stream=False, size=None, exception_handler=None, gtimeout=None): """Concurrently converts a list of Requests to Responses. :param requests: a collection of Request objects. :param stream: If True, the content will not be downloaded immediately. :param size: Specifies the number of requests to make at a time. If None, no throttling occurs. :param exception_handler: Callback function, called when exception occured. Params: Request, Exception :param gtimeout: Gevent joinall timeout in seconds. (Note: unrelated to requests timeout) """ requests = list(requests) pool = Pool(size) if size else None jobs = [send(r, pool, stream=stream) for r in requests] gevent.joinall(jobs, timeout=gtimeout) ret = [] for request in requests: if request.response is not None: ret.append(request.response) elif exception_handler and hasattr(request, ‘exception‘): ret.append(exception_handler(request, request.exception)) else: ret.append(None) return ret
内部其实就是循环请求列表发起的请求,然后对返回的结果进行判断,然后添加到ret列表中,最终return ret就是最后我们看到的一个可迭代对象了。
>>> def exception_handler(request, exception): ... print "Request failed" >>> reqs = [ ... grequests.get(‘http://httpbin.org/delay/1‘, timeout=0.001), ... grequests.get(‘http://fakedomain/‘), ... grequests.get(‘http://httpbin.org/status/500‘)] >>> grequests.map(reqs, exception_handler=exception_handler) Request failed Request failed [None, None, <Response [500]>]
标签:call iat red 可迭代对象 exception occurs else current none
原文地址:https://www.cnblogs.com/tulintao/p/12379919.html