tornado add block task to ThreadPool

backgroudmix.py

from time import sleep
import tornado
from multiprocessing.pool import ThreadPool

_workers = ThreadPool(10)

class BackgroundMix(tornado.web.RequestHandler):
    """将block任务放入线程池中执行
    EXAMPLE:
        # blocking task like querying to MySQL
        def blocking_task(n):
            sleep(n)
            return n

        class Handler(RequestHandler, BackgroundMix):
            @asynchronous
            def get(self):
                self.run_background(blocking_task, self.on_complete, (10,))

            def on_complete(self, res):
                self.write("Test {0}<br/>".format(res))                                                                                                                                                                                                                       
                self.finish()
    """
    def run_background(self, func, callback, args=(), kwds={}):
        self.ioloop = tornado.ioloop.IOLoop.instance()

        def _callback(result):
            self.ioloop.add_callback(lambda: callback(result))
        _workers.apply_async(func, args, kwds, _callback)

这个有两个地方不好用

1. 无法处理任务抛出的异常

2. 原来的任务比如是blocking_task(10)，这里run_background的最后一个参数却不一样，具体是这样的

   t(10) ---> run_background(t, self.on_t, (10,))
   t(10,20) ---> run_background(t, self.on_t, (10,20))
   t(10,a=20) --> run_background(t, self.on_t, (10,), {'a':20})