use grequests in Flask with strange error

[pengyusong]

i‘ import grequests in flask blueprints, because i want send multi requests in one http request of flask. but i encountered a problem:

eventpoll fd will be increased for every http request, even if the http request does not use grequests.

I use ‘strace -p’ to get something deeply:

Compared with normal case, it add two ‘fcntl ‘ system call, they change the socket type to O_NONBLOCK.

it shows as follows:
accept(3, {sa_family=AF_INET, sin_port=htons(58226), sin_addr=inet_addr("192.168.1.14")}, [16]) = 9 fcntl(9, F_GETFL) = 0x2 (flags O_RDWR) fcntl(9, F_SETFL, O_RDWR|O_NONBLOCK) = 0

Notice:
i use werkzeug server to start flask will raise up this problem, if i use uwsgi etc. the problem will not occur.

questions:

1. dose grequests lib will infect outside socket(flask) ?
2. if above answer is true, how to avoid it?

[spyoungtech]

Because of the monkey-patching, importing grequests does end up potentially touching, and potentially breaking lot of other libraries. There are a number of other related issues that have been opened in the same light. Perhaps one of those may contain a clue to a possible solution. It would likely take a lot of effort to get down to the bottom of the cause, let alone a solution.

In my experience grequests works great in many cases. But if it doesn't work for your particular case, you may want to consider using, as the README now suggests, requests-threads or requests-futures instead.

Closing this for now. If you can provide some more details or other discoveries, we can reopen.