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Author superwesman
Recipients superwesman
Date 2007-10-10.17:41:48
SpamBayes Score 0.00629202
Marked as misclassified No
Message-id <>
hi - I noticed some odd behaviour with subprocess when the output
(stdout) is large - I did some sleuthing and found a reproduceable case
- I tested this on solaris using python 2.4.2 (sparc) and using 2.5
(opteron) - I've attached a python script that details the problem - I
created 2 files ("small_file" and "large_file") that are 20480 and 20481
bytes, respectively ....

> ls -lrt ./tmp/*_file
-rw-r--r--   1 wtorres  staff      20481 Oct 10 12:32 ./tmp/large_file
-rw-r--r--   1 wtorres  staff      20480 Oct 10 12:32 ./tmp/small_file

the script cats each file, thus generating an appropriately sized stdout
- the workaround we came up with was to use our own file handle and use
the parameter stdout=my_file_handle.fileno() instead of stdout=PIPE -
you can see this in the attached example as well

> python ./tmp/ 
testing with a small file - these should both work
using my own file handle .... ok
using PIPE ... ok
testing with a large file - the second one here should fail
using my own file handle .... ok
using PIPE ...
Traceback (most recent call last):
  File "./tmp/", line 43, in ?
    test_popen_bug( large_file )
  File "./tmp/", line 31, in test_popen_bug
    rc = my_popen.wait()
  File "/tools/python/2.4.2/solaris/lib/python2.4/", line
1007, in wait
    pid, sts = os.waitpid(, 0)

based on all this, it seems that the PIPE file handle has some buffer or
something that is filling up and not allowing us to continue... or
something.  Thoughts?
File name Uploaded superwesman, 2007-10-10.17:41:48
Date User Action Args
2007-10-10 17:41:50superwesmansetspambayes_score: 0.00629202 -> 0.00629202
recipients: + superwesman
2007-10-10 17:41:49superwesmansetspambayes_score: 0.00629202 -> 0.00629202
messageid: <>
2007-10-10 17:41:49superwesmanlinkissue1256 messages
2007-10-10 17:41:48superwesmancreate