This looks like a tornado problem, but trust me, it is almost all about the mechanism of multiprocessing module.
I borrowed the idea from http://gist.github.com/312676 to implement an async db query web service using tornado. p = multiprocessing.Pool(4) class QueryHandler(tornado.web.RequestHandler): ... @tornado.web.asynchronous def get(self): ... p.apply_async(async_func, [sql_command, arg1, arg2, arg3, ], callback_func) def callback_func(self, data): self.write(data) def async_func(sql_command, arg1, arg2, arg3): ''' do the actual query job ''' ... # data is the query result by executing sql_command return data So the workflow is like this, get() --> fork a subprocess to process the query request in async_func() -> when async_func() returns, callback_func uses the return result of async_func as the input argument, and send the query result to the client. So the problem is the the query result as the result of sql_command might be too big to store them all in the memory, which in our case is stored in the variable "data". Can I send return from the async method early, say immediately after the query returns with the first result set, then stream the results to the browser. In other words, can async_func somehow notify callback_func to prepare receiving the data before async_func actually returns? -- http://mail.python.org/mailman/listinfo/python-list
