On Tuesday, January 14, 2020 at 4:45:27 PM UTC+8, Nadav Har'El wrote:
>
>
> On Tue, Jan 14, 2020 at 10:15 AM Lewis Tian <tase...@gmail.com
> <javascript:>> wrote:
>
>>
>>
>> On Tuesday, January 14, 2020 at 3:45:09 PM UTC+8, Nadav Har'El wrote:
>>>
>>>
>>> On Tue, Jan 14, 2020 at 9:28 AM Lewis Tian <tase...@gmail.com> wrote:
>>>
>>>> When I run pagerank on Ubuntu, the code works fine. (the graph data is
>>>> stored in web-NotreDame.txt, 21M)
>>>>
>>>
>>> 21M isn't very large, it shouldn't present any special problems. We
>>> probably have a bug that isn't just about file size:
>>>
>>>
>>>> taseikyo@ubuntu:~/Desktop/osv/apps/my-pagerank-test$ ls
>>>> Makefile module.py pagerank.c usr.manifest web-NotreDame.txt
>>>>
>>>> taseikyo@ubuntu:~/Desktop/osv/apps/my-pagerank-test$ make
>>>> cc -pie -o pagerank pagerank.c
>>>>
>>>> taseikyo@ubuntu:~/Desktop/osv/apps/my-pagerank-test$ ll -h
>>>> total 21M
>>>> drwxrwxr-x 2 taseikyo taseikyo 4.0K Jan 14 11:59 ./
>>>> drwxrwxr-x 128 taseikyo taseikyo 4.0K Jan 14 11:51 ../
>>>> -rw-rw-r-- 1 taseikyo taseikyo 110 Jan 14 11:51 Makefile
>>>> -rw-rw-r-- 1 taseikyo taseikyo 60 Jan 13 11:26 module.py
>>>> -rwxrwxr-x 1 taseikyo taseikyo 17K Jan 14 11:59 pagerank*
>>>> -rw-rw-r-- 1 taseikyo taseikyo 5.6K Jan 14 11:51 pagerank.c
>>>> -rw-rw-r-- 1 taseikyo taseikyo 85 Jan 14 11:53 usr.manifest
>>>> -rw-rw-r-- 1 taseikyo taseikyo 21M Jan 14 11:54 web-NotreDame.txt
>>>>
>>>> taseikyo@ubuntu:~/Desktop/osv/apps/my-pagerank-test$ ./pagerank
>>>> Graph data:
>>>>
>>>> Nodes: 325729, Edges: 1497134
>>>>
>>>>
>>>> Number of iteration to converge: 52
>>>>
>>>> Final Pagerank values:
>>>> [0.002066 , 0.000181 , ...]
>>>>
>>>> Time spent: 0.896491 seconds.
>>>>
>>>> But when I build and run pagerank on osv, it fails to read the graph
>>>> data (only read part of the graph).
>>>>
>>>> taseikyo@ubuntu:~/Desktop/osv$ ./scripts/build image=my-pagerank-test
>>>> taseikyo@ubuntu:~/Desktop/osv$ ./scripts/run.py
>>>> OSv v0.54.0-71-g69a0ce39
>>>> eth0: 192.168.122.15
>>>> Booted up in 338.86 ms
>>>> Cmdline: /pagerank
>>>>
>>>> Graph data:
>>>>
>>>> Nodes: 325729, Edges: 1497134
>>>>
>>>> Fail to read data...
>>>>
>>>> From: 6 To: 119
>>>>
>>>> Here is part of the code:
>>>>
>>>> while (!feof(fp)) {
>>>> fret = fscanf(fp, "%d%d", &fromnode, &tonode);
>>>> if (fret == 0) {
>>>> printf("Fail to read data...\n");
>>>> printf("\n From: %d To: %d\n",fromnode, tonode);
>>>> return -1;
>>>> }
>>>> ...
>>>> }
>>>>
>>>>
>>> Maybe we have a bug in fscanf or in the stdio reading layer?
>>> Things I'd like you to please check:
>>> 1. Print a failure already if fret < 2 - since 1 is also a failure.
>>> 2. On failure, please print ftell(fp) - our position in the file (is it
>>> the end? something in the middle?). Please also do a fgets() or a short
>>> fgetc() loop or fread() to read the next available bytes, to try to
>>> understand by fscanf() failed. Is the reading from the file failing, or is
>>> the parsing failing?
>>>
>>>
>> Thanks for your advice,
>> On failure, the output is as follows:
>>
>> Graph data:
>>
>> Nodes: 325729, Edges: 1497134
>>
>> fret: 1
>> position: 1025
>> next char:
>>
>> fret is 1, fp is in the middle, fgetc or fgets cannot read anything. I
>> think it should be the former case.
>>
>
> Interesting. Smells like a serious stdio bug that needs to be debugged :-(
> I think it's not a coincidence that position is 1025, with stdio's
> BUFSIZ=1024.
>
> Just as a completely wild guess, can you please try if the following patch
> to libc/internal/shgetc.c helps?
>
> @@ -22,5 +22,6 @@
> else
> f->shend = f->rend;
> if (f->rend) f->shcnt += f->rend - f->rpos + 1;
> + if (f->rpos[-1] != c) f->rpos[-1] = c;
> return c;
> }
>
>
Yeah, the patch is helpful! Thanks! : )
>
>>
>>
>>>
>>>
>>>> When I use a small graph (4 nodes, 7 edges), it runs normally.
>>>>
>>>> taseikyo@ubuntu:~/Desktop/osv$ ./scripts/build image=my-pagerank-test
>>>> taseikyo@ubuntu:~/Desktop/osv$ ./scripts/run.py
>>>> OSv v0.54.0-71-g69a0ce39
>>>> eth0: 192.168.122.15
>>>> Booted up in 356.44 ms
>>>> Cmdline: /pagerank
>>>>
>>>> Graph data:
>>>>
>>>> Nodes: 4, Edges: 7
>>>>
>>>>
>>>> Number of iteration to converge: 41
>>>>
>>>> Final Pagerank values:
>>>>
>>>> [0.159913 , 0.144016 , 0.144016 , 0.082809 ]
>>>>
>>>> Time spent: 0.693802 seconds.
>>>>
>>>> Is osv unable to read large files (bug?) I'll appreciate your help very
>>>> much! : )
>>>>
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