.. _ref-extensions: ============================= Built-in extensions reference ============================= This document explains all extensions that come with Scrapy. For information on how to use them and how to write your own extensions, see the :ref:`extensions usage guide `. General purpose extensions ========================== Core Stats extension -------------------- .. module:: scrapy.stats.corestats :synopsis: Core stats collection .. class:: scrapy.stats.corestats.CoreStats Enable the collection of core statistics, provided the stats collection are enabled (see :ref:`topics-stats`). Response Libxml2 extension -------------------------- .. module:: scrapy.xpath.extension :synopsis: Libxml2 document caching for Responses .. class:: scrapy.path.extension.ResponseLibxml2 Causes the :class:`~scrapy.http.Response` objects to grow a new method (``getlibxml2doc()``) which returns a (cached) libxml2 document of their contents. :ref:`XPath Selectors ` use this extension for better performance, so it's highly recommended not to disable it. .. _ref-extensions-webconsole: Web console extension --------------------- .. module:: scrapy.management.web :synopsis: Web management console .. class:: scrapy.management.web.WebConsole Provides an extensible web server for managing a Scrapy process. It's enabled by the :setting:`WEBCONSOLE_ENABLED` setting. The server will listen in the port specified in :setting:`WEBCONSOLE_PORT`, and will log to the file specified in :setting:`WEBCONSOLE_LOGFILE`. The web server is designed to be extended by other extensions which can add their own management web interfaces. See also :ref:`topics-webconsole` for information on how to write your own web console extension, and "Web console extensions" below for a list of available built-in (web console) extensions. .. _ref-extensions-telnetconsole: Telnet console extension ------------------------ .. module:: scrapy.management.telnet :synopsis: Telnet management console .. class:: scrapy.management.telnet.TelnetConsole Provides a telnet console for getting into a Python interpreter inside the currently running Scrapy process, which can be very useful for debugging. The telnet console must be enabled by the :setting:`TELNETCONSOLE_ENABLED` setting, and the server will listen in the port specified in :setting:`WEBCONSOLE_PORT`. Spider reloader extension ------------------------- .. module:: scrapy.contrib.spider.reloader :synopsis: Spider reloader extension .. class:: scrapy.contrib.spider.reloader.SpiderReloader Reload spider objects once they've finished scraping, to release the resources and references to other objects they may hold. .. _ref-extensions-memusage: Memory usage extension ---------------------- .. module:: scrapy.contrib.memusage :synopsis: Memory usage extension .. class:: scrapy.contrib.memusage.MemoryUsage Allows monitoring the memory used by a Scrapy process and: 1, send a notification email when it exceeds a certain value 2. terminate the Scrapy process when it exceeds a certain value The notification emails can be triggered when a certain warning value is reached (:setting:`MEMUSAGE_WARNING_MB`) and when the maximum value is reached (:setting:`MEMUSAGE_LIMIT_MB`) which will also cause the Scrapy process to be terminated. This extension is enabled by the :setting:`MEMUSAGE_ENABLED` setting and can be configured with the following settings: * :setting:`MEMUSAGE_LIMIT_MB` * :setting:`MEMUSAGE_WARNING_MB` * :setting:`MEMUSAGE_NOTIFY_MAIL` * :setting:`MEMUSAGE_REPORT` Memory debugger extension ------------------------- .. module:: scrapy.contrib.memdebug :synopsis: Memory debugger extension .. class:: scrapy.contrib.memdebug.MemoryDebugger A memory debugger which collects some info about objects uncollected by the garbage collector and libxml2 memory leaks. To enable this extension turn on the :setting:`MEMDEBUG_ENABLED` setting. The report will be printed to standard output. If the :setting:`MEMDEBUG_NOTIFY` setting contains a list of emails the report will also be sent to those addresses. Close domain extension ---------------------- .. module:: scrapy.contrib.closedomain :synopsis: Close domain extension .. class:: scrapy.contrib.closedomain.CloseDomain Allows a domain/spider to be automatically closed when some conditions are met and optionally notifies a list of emails if the :setting:`CLOSEDOMAIN_NOTIFY` is set. The conditions for auto-closing a domain can be configured thorough these settings: * :setting:`CLOSEDOMAIN_TIMEOUT` - an integer which specifies a number of seconds. If the domain remains open for more than that time, it will be closed. Other conditions will be supported in the future. Stack trace dump extension --------------------------- .. module:: scrapy.contrib.debug :synopsis: Extensions for debugging Scrapy .. class:: scrapy.contrib.debug.StackTraceDump Adds a `SIGUSR1`_ signal handler which dumps the stack trace of a runnning Scrapy process when a ``SIGUSR1`` signal is catched. After the stack trace is dumped, the Scrapy process continues to run normally. The stack trace is sent to standard output, or to the Scrapy log file if :setting:`LOG_STDOUT` is enabled. This extension only works on POSIX-compliant platforms (ie. not Windows). .. _SIGUSR1: http://en.wikipedia.org/wiki/SIGUSR1_and_SIGUSR2 Response soup extension ----------------------- .. module:: scrapy.contrib.response.soup :synopsis: Response soup extension .. class:: scrapy.contrib.response.soup.ResponseSoup The ResponseSoup extension causes the :class:`~scrapy.http.Response` objects to grow a new method (``getsoup()``) which returns a cached `BeautifulSoup`_ object of their body, and a ``soup`` attribute with the same effect. The ``soup`` attribute is provided only for convenience, as you cannot pass pass any BeautifulSoup constructor arguments (use the ``getsoup()`` method for those cases). The advantage of using the Response soup extension over instantiating a BeautifulSoup object directly is performance, as BeautifulSoup is known to be very slow. For example, if you have a downloader middleware and a spider that both need to construct a BeautifulSoup object of the responses, you would be constructing two BeautifulSoup objects unless you use this extension which caches the first one. .. _BeautifulSoup: http://www.crummy.com/software/BeautifulSoup/documentation.html StatsMailer extension --------------------- .. module:: scrapy.contrib.statsmailer :synopsis: StatsMailer extension .. class:: scrapy.contrib.statsmailer.StatsMailer This simple extension can be used to send a notification email every time a domain has finished scraping, including the Scrapy stats collected. The email will be sent to all recipients specified in the :setting:`STATSMAILER_RCPTS` setting. Web console extensions ====================== .. module:: scrapy.contrib.webconsole :synopsis: Contains most built-in web console extensions Here is a list of built-in web console extensions. For clarity "web console extension" is abbreviated as "WC extension". For more information see the see the :ref:`web console documentation `. Scheduler queue WC extension ---------------------------- .. module:: scrapy.contrib.webconsole.scheduler :synopsis: Scheduler queue web console extension .. class:: scrapy.contrib.webconsole.scheduler.SchedulerQueue Display a list of all pending Requests in the Scheduler queue, grouped by domain/spider. Spider live stats WC extension ------------------------------ .. module:: scrapy.contrib.webconsole.livestats :synopsis: Spider live stats web console extension .. class:: scrapy.contrib.webconsole.livestats.LiveStats Display a table with stats of all spider crawled by the current Scrapy run, including: * Number of items scraped * Number of pages crawled * Number of pending requests in the scheduler * Number of pending requests in the downloader queue * Number of requests currently being downloaded Engine status WC extension --------------------------- .. module:: scrapy.contrib.webconsole.enginestatus :synopsis: Engine status web console extension .. class:: scrapy.contrib.webconsole.enginestatus.EngineStatus Display the current status of the Scrapy Engine, which is just the output of the Scrapy engine ``getstatus()`` method. Stats collector dump WC extension ---------------------------------- .. module:: scrapy.contrib.webconsole.stats :synopsis: Stats dump web console extension .. class:: scrapy.contrib.webconsole.stats.StatsDump Display the stats collected so far by the stats collector. Spider stats WC extension ------------------------- .. module:: scrapy.contrib.webconsole.spiderstats :synopsis: Spider stats web console extension .. class:: scrapy.contrib.webconsole.spiderstats.SpiderStats