我想用多執行緒查詢資料庫，然後進行資料操作。
_list = range(19999, 100000)
pool = threadpool(10)
results = pool.map(main, _list)
pool.close()
pool.join()
def main(i):
print(i)
# query id, link, keywords in db
res = query('select id,link,keywords from articles where id = {}'.format(i))
但是報錯如下，是資料庫扛不住這樣的查詢還是啥意思？
traceback (most recent call last):
file "main.py", line 60, in
results = pool.map(main, _list)
file "/usr/local/cellar/python3/3.5.1/frameworks/python.framework/versions/3.5/lib/python3.5/multiprocessing/pool.py", line 260, in map
return self._map_async(func, iterable, mapstar, chunksize).get()
file "/usr/local/cellar/python3/3.5.1/frameworks/python.framework/versions/3.5/lib/python3.5/multiprocessing/pool.py", line 608, in get
raise self._value
file "/usr/local/cellar/python3/3.5.1/frameworks/python.framework/versions/3.5/lib/python3.5/multiprocessing/pool.py", line 119, in worker
result = (true, func(*args, **kwds))
file "/usr/local/cellar/python3/3.5.1/frameworks/python.framework/versions/3.5/lib/python3.5/multiprocessing/pool.py", line 44, in mapstar
return list(map(*args))
file "main.py", line 17, in main
res = gao_query('select id,link,keywords from articles where id = {}'.format(i))
file "/users/ru/desktop/crawl_keywords/db.py", line 13, in query_with_desc
for res in cur.fetchall():
psycopg2.programmingerror: no results to fetch
(py3)
query函式如下: 返回資料以字典格式，keys為colomn名。
query = partial(query_with_desc, cur)
def query_with_desc(cur, sql):
cur: postgresl cursor
sql: sql statement
cur.execute(sql)
index = cur.description
result =
for res in cur.fetchall():
row = {}
for i in range(len(index)):
row[index[i][0]] = res[i]
return result
python錯誤捕捉
python使用try except捕捉錯誤，當發現錯誤時無需從底層向上依次返回錯誤 而是直接丟擲異常。通常使用方法 try 執行語句，發生錯誤時後續語句不在執行，轉至except except 處理該型別的錯誤 except else 無錯誤發生時執行此處 finally 不管有無錯誤都會執行 錯...
php 捕捉mysql錯誤 PHP捕捉錯誤
php捕捉錯誤 禁止錯誤輸出 error reporting 0 設定錯誤處理器 set error handler errorhandler 在指令碼結束時執行的函式 register shutdown function fatalerrorhandler 錯誤處理 param int err n...
php錯誤及異常捕捉
在實際開發中，錯誤及異常捕捉僅僅靠try catch 是遠遠不夠的。所以引用以下幾中函式。a set error handler 一般用於捕捉 e notice e user error e user warning e user notice 不能捕捉 e error,e parse,e core...