0.參考
Scrapy 隱含 bug: 強制關閉爬蟲後從 requests.queue 讀取的已保存 request 數量可能有誤
1.說明
Scrapy 設置 jobdir,停止爬蟲後,保存文件目錄結構:
crawl/apps/
├── requests.queue
│ ├── active.json
│ ├── p0
│ └── p1
├── requests.seen
└── spider.state
requests.queue/p0 文件保存 priority=0 的未調度 request, p-1 對應實際 priority=1 的高優先級 request,轉移到 redis 有序集合時,score 值越小排序越靠前,因此取 score 爲 -1。以此類推,p1 對應 priority=-1 的低優先級 request。
requests.seen 保存請求指紋過濾器對已入隊 request 的 hash 值,每行一個值。
spider.state 涉及自定義屬性的持久化存儲,不在本文處理範圍以內。
2.實現代碼
import os from os.path import join import re import struct import redis def sadd_dupefilter(jobdir, redis_server, name): """See python/lib/site-packages/scrapy/dupefilters.py""" file = join(jobdir, 'requests.seen') with open(file) as f: print('Processing %s, it may take minutes...'%file) key = '%s:dupefilter'%name for x in f: redis_server.sadd(key, x.rstrip()) print('Result: {} {}'.format(key, redis_server.scard(key))) def zadd_requests(jobdir, redis_server, name): """See python/lib/site-packages/queuelib/queue.py""" SIZE_FORMAT = ">L" SIZE_SIZE = struct.calcsize(SIZE_FORMAT) key = '%s:requests'%name queue_dir = join(jobdir, 'requests.queue') file_list = os.listdir(queue_dir) file_score_dict = dict([(f, int(f[1:])) for f in file_list if re.match(r'^p-?\d+$', f)]) for (file, score) in file_score_dict.items(): print('Processing %s, it may take minutes...'%file) f = open(join(queue_dir, file), 'rb+') qsize = f.read(SIZE_SIZE) total_size, = struct.unpack(SIZE_FORMAT, qsize) f.seek(0, os.SEEK_END) actual_size = 0 while True: if f.tell() == SIZE_SIZE: break f.seek(-SIZE_SIZE, os.SEEK_CUR) size, = struct.unpack(SIZE_FORMAT, f.read(SIZE_SIZE)) f.seek(-size-SIZE_SIZE, os.SEEK_CUR) data = f.read(size) redis_server.execute_command('ZADD', key, score, data) f.seek(-size, os.SEEK_CUR) actual_size += 1 print('total_size {}, actual_size {}, score {}'.format( total_size, actual_size, score)) print('Result: {} {}'.format(key, redis_server.zlexcount(key, '-', '+'))) if __name__ == '__main__': name = 'test' jobdir = '/home/yourproject/crawl/apps' database_num = 0 # apps/ # ├── requests.queue # │ ├── active.json # │ ├── p0 # │ └── p1 # ├── requests.seen # └── spider.state password = 'password' host = '127.0.0.1' port = '6379' redis_server = redis.StrictRedis.from_url('redis://:{password}@{host}:{port}/{database_num}'.format( password=password, host=host, port=port, database_num=database_num)) sadd_dupefilter(jobdir, redis_server, name) zadd_requests(jobdir, redis_server, name)
3.運行結果