Concurrent uploads completely broken since V2 api.

Stefan D.6

It appears that uploading multiple different files to the same dropbox at the same time, is completely broken in the V2 api. Even if 2 different computers are uploading a file. Please see the following testcase:

 

 

#!/bin/env python2

import tempfile

 

import dropbox

 

FILE = ""

ACCESSTOKEN = ""

 

client = dropbox.Dropbox(ACCESSTOKEN)

 

for i in range(10000):

    with tempfile.NamedTemporaryFile() as fp:

        metadata, restdata = client.files_download(FILE)

        fp.write(restdata.content)

        fp.write("{}\n".format(i))

        fp.seek(0)

        client.files_upload(fp, FILE, dropbox.files.WriteMode('overwrite', None))

 

 

 

 

Steps to reproduce:

fill in your accesstoken.

fill in in the variables FILE, to a file that exists ('/foo/test.txt'). Start the program.

Change the variable FILE to another file that exists ('/foo/test2.txt'). Start another instance of the program

 

 

What should happen is that both test.txt and test2.txt are continuously appended with an new integer followed by a newline. But in practice, the files occasionally end up completely empty after an update cycle. The download of the file does not fail. client.files_upload simply creates an completely empty file.

 

This behavior is not reproduceable when running only one instance of this testcase. Running the testcase on one computer or on different computers/ip's with different/same accesstokens/accounts does not make a difference in my testing as long as the same dropbox (or dropbox folder?) is accessed.

 

Time to reproduce: about 10 updates. Might depend on your internet connection and proximity to dropbox' servers. (not tested)

 

Tested with dropbox 6.8.0 on windows 10 and dropbox 6.5.0 on debian. Only tested with python 2.7

Greg-DB

Thanks for the report Stefan! I just tried running two of these though and I'm not seeing the same behavior, using the same version of Python and the Dropbox library.

How are you checking the file size to see the unexpected empty file? Can you add some logging and share the output showing the issue? In particular, it might be good to check the size in three places: in the metadata returned by files_download, of fp itself, and in the metadata returned by files_upload. That way we can see exactly when/where the empty file originates.

Thanks in advance!