mirror of https://github.com/scrapy/scrapy.git
104 lines
2.7 KiB
ReStructuredText
104 lines
2.7 KiB
ReStructuredText
.. _topics-stats:
|
|
|
|
================
|
|
Stats Collection
|
|
================
|
|
|
|
Scrapy provides a convenient facility for collecting stats in the form of
|
|
key/values, where values are often counters. The facility is called the Stats
|
|
Collector, and can be accessed through the :attr:`~scrapy.crawler.Crawler.stats`
|
|
attribute of the :ref:`topics-api-crawler`, as illustrated by the examples in
|
|
the :ref:`topics-stats-usecases` section below.
|
|
|
|
The Stats Collector API is always available, so you can always use it (to
|
|
increment or set new stat keys), regardless
|
|
of whether the stats collection is enabled or not. If it's disabled, the API
|
|
will still work but it won't collect anything. This is aimed at simplifying the
|
|
stats collector usage: you should spend no more than one line of code for
|
|
collecting stats in your spider, Scrapy extension, or whatever code you're
|
|
using the Stats Collector from.
|
|
|
|
Another feature of the Stats Collector is that it's very efficient (when
|
|
enabled) and extremely efficient (almost unnoticeable) when disabled.
|
|
|
|
.. _topics-stats-usecases:
|
|
|
|
Common Stats Collector uses
|
|
===========================
|
|
|
|
Access the stats collector through the :attr:`~scrapy.crawler.Crawler.stats`
|
|
attribute. Here is an example of an extension that access stats:
|
|
|
|
.. code-block:: python
|
|
|
|
class ExtensionThatAccessStats:
|
|
def __init__(self, stats):
|
|
self.stats = stats
|
|
|
|
@classmethod
|
|
def from_crawler(cls, crawler):
|
|
return cls(crawler.stats)
|
|
|
|
.. skip: start
|
|
|
|
Set stat value:
|
|
|
|
.. code-block:: python
|
|
|
|
stats.set_value("hostname", socket.gethostname())
|
|
|
|
Increment stat value:
|
|
|
|
.. code-block:: python
|
|
|
|
stats.inc_value("custom_count")
|
|
|
|
Set stat value only if greater than previous:
|
|
|
|
.. code-block:: python
|
|
|
|
stats.max_value("max_items_scraped", value)
|
|
|
|
Set stat value only if lower than previous:
|
|
|
|
.. code-block:: python
|
|
|
|
stats.min_value("min_free_memory_percent", value)
|
|
|
|
Get stat value:
|
|
|
|
.. code-block:: pycon
|
|
|
|
>>> stats.get_value("custom_count")
|
|
1
|
|
|
|
Get all stats:
|
|
|
|
.. code-block:: pycon
|
|
|
|
>>> stats.get_stats()
|
|
{'custom_count': 1, 'start_time': datetime.datetime(2009, 7, 14, 21, 47, 28, 977139)}
|
|
|
|
.. skip: end
|
|
|
|
Available Stats Collectors
|
|
==========================
|
|
|
|
.. currentmodule:: scrapy.statscollectors
|
|
|
|
Besides the basic :class:`StatsCollector` there are other Stats Collectors
|
|
available in Scrapy which extend the basic Stats Collector. You can select
|
|
which Stats Collector to use through the :setting:`STATS_CLASS` setting. The
|
|
default Stats Collector used is the :class:`MemoryStatsCollector`.
|
|
|
|
MemoryStatsCollector
|
|
--------------------
|
|
|
|
.. autoclass:: MemoryStatsCollector
|
|
:members:
|
|
|
|
DummyStatsCollector
|
|
-------------------
|
|
|
|
.. autoclass:: DummyStatsCollector
|