[Udpcast] Experiencing reproducible corruption when using udpcast-20090912

Alain Knaff alain at knaff.lu
Mon Sep 21 08:03:39 CEST 2009


John Eisenman wrote:
> John Eisenman wrote:
>> John Eisenman wrote:
>>   
>>> I'm new to udpcast and so may be doing something wrong.  However, I find
>>> that with the latest two versions (udpcast-20090912 or
>>> udpcast-20090830), I experience repeated file corruption.  I've had
>>> better, but not perfect,  success with an old version (udpcast-20071228).
>>>
>>> In order to test, I made an ordered file, 500MB in size:
>>>
>>> cl6 tmp # ls -l test-52428800.dat
>>> -rw-r--r-- 1 jice jice 524288000 Sep 15 17:52 test-52428800.dat
>>> cl6 tmp # head -14 test-52428800.dat
>>> 000000000
>>> 000000001
>>> 000000002
>>> 000000003
>>> 000000004
>>> 000000005
>>> 000000006
>>> 000000007
>>> 000000008
>>> 000000009
>>> 000000010
>>> 000000011
>>> 000000012
>>> 000000013
>>>
>>> I find that every time I send and receive a file, it is the correct
>>> length.  However, certain data is missing and other data is repeated.  
>>>
>>> Here is an example of my command line to send the data:
>>>
>>> udp-sender --log udpcast.log --bw-period 1 --nokbd --min-receivers 1
>>> --min-wait 5 --portbase 9010 -f test-52428800.dat --pointopoint
>>>
>>> Here is my command line to receive data:
>>>
>>> udp-receiver  -f test2 --nokbd --portbase 9010
>>>
>>> I have test result files that I can provide if they would be helpful.
>>>
>>> I am running under Gentoo on AMD64 processors.  I've tried under two
>>> different kernels:
>>>
>>> # uname -a
>>> Linux cl7 2.6.20-gentoo-r8 #1 SMP PREEMPT Wed Aug 22 14:28:25 PDT 2007
>>> x86_64 AMD Opteron(tm) Processor 246 AuthenticAMD GNU/Linux
>>>
>>> # uname -a
>>> Linux m231 2.6.30-gentoo-r4pb #2 SMP Thu Aug 27 18:41:51 PDT 2009 x86_64
>>> Quad-Core AMD Opteron(tm) Processor 2374 HE AuthenticAMD GNU/Linux
>>>
>>>
>>>
>>>   
>>>     
>> Additional information:
>>
>> By running in async mode (and setting an fec), I find that I am able to 
>> produce a non-corrupt output file.  Perhaps this provides a clue as to 
>> the source of the problem.
>>
>>
>>   
> Another odd clue.  The corruption appears to depend on running the 
> udp-sender (udpcast-20090912) as root.  When running the udp-sender as 
> another user, there is no corruption. 
> 
> Yes, quite odd.  But, does it ring any bells?

There was indeed an issue introduced together with the recent support
for "streaming" mode. This is now fixed in 20090920.

Regards,

Alain



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