Network resources for TCP connections in python [Windows]

Question

Not sure if I have myself a problem with a python script I'm using. Basically, it spawns threads, each creating a tcp connections. Well the script finishes, i even check if any threads are still functioning, all of them return False ( not active which is good).

The issue is that, if I check ( I use CurPorts from nirsoft ) some tcp connections ( between 1 and 9 sometimes ) are still in established status and sometimes in Sent status. Is that a problem ?They die out eventually, but after several minutes. IS that on python's side fault, or basic windows procedure?

I close the sockets with S.close, if that's of any help. I'm not using daemon threads, just simple threads, and I just wait until all of them finish (t.join())

I need to know i I should worry or just let them be. reason is that they are eating up the ephemeral port number, and besides that i do not know if its keeping resources from me.

Would appreciate a noob friendly response.

Last Edit: I do use S.shutdown() before I send S.close() I do not do any error checking though, I have no idea how to go about doing that besides try:

Would help to include a minimal code example which demonstrates the problem. — Aya
– Aya, Commented Jun 17, 2013 at 12:06
possible duplicate of How do you close TCP connections gracefully without exceptions? — Didier Trosset
– Didier Trosset, Commented Jun 17, 2013 at 12:13

Community · Accepted Answer · 2017-05-23 12:21:34Z

1

The simple answer is that TCP connections need to be gracefully shutdown before being closed.

There are more details on how to call shutdown and close there:

edited May 23, 2017 at 12:21

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answered Jun 17, 2013 at 12:15

Didier Trosset

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3 Comments

Ichabod Crane Over a year ago

I do send S.shutdown() before S.close(), also I use non blocking sockets, but not by using select(), but by using setblocking(0) and settimeout(15) for the entire socket

Ichabod Crane Over a year ago

Edit: So far, after script finishes, the Established and Sent tcp connections do die in about 1 and a half minutes in average. Is it normal? Should I just leave it like that and go with it? I changed shutdown() and close() to shutdown(1) and close()

Didier Trosset Over a year ago

Have a look at the third link. It explains in a table that you should (IIUC): shutdown(WR), and wait for FD_CLOSE, close().

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