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digitalmars.D.learn - halting problem :)

reply "Saaa" <empty needmail.com> writes:
My program doesn't exit..

void main()
{

..
Data data[]

createData(data);
//This proces takes a minute or two.
//data now holds about 700000 Data elements

 writefln(`Creating buffer`);
 ubyte[] buffer;
 for (int i=0; i<data.length; i++)
 {
  buffer~=format(data[i].net,`,`,data[i].name,`,`,to!(int[])(data[i].output),`,`,to!(int[])(data[i].input),newline);
  //This takes like a minute and has a peak memory usage of 680MB
 }

 writefln(`Writing file`);
 std.file.write(outFilename, buffer);
writefln(`Writing file finished`);

//The file is readily made and delta memory usage shows a few a few times 
around 20MB
//but the program doesn't stop, although 'Writing file finished' is shown.
//there is no static this or alike.
//and after 10 minutes the memory usage is about 370MB and slowly going up
//ctrl-c doesn't work anymore as well
}
Jan 27 2009
next sibling parent reply Jarrett Billingsley <jarrett.billingsley gmail.com> writes:
On Tue, Jan 27, 2009 at 10:14 AM, Saaa <empty needmail.com> wrote:

 My program doesn't exit..

 void main()
 {

 ..
 Data data[]

 createData(data);
 //This proces takes a minute or two.
 //data now holds about 700000 Data elements

  writefln(`Creating buffer`);
  ubyte[] buffer;
  for (int i=0; i<data.length; i++)
  {
  buffer~=format(data[i].net,`,`,data[i].name,`,`,to!(int[])(data[i].output),`,`,to!(int[])(data[i].input),newline);
  //This takes like a minute and has a peak memory usage of 680MB
  }

  writefln(`Writing file`);
  std.file.write(outFilename, buffer);
 writefln(`Writing file finished`);

 //The file is readily made and delta memory usage shows a few a few times
 around 20MB
 //but the program doesn't stop, although 'Writing file finished' is shown.
 //there is no static this or alike.
 //and after 10 minutes the memory usage is about 370MB and slowly going up
 //ctrl-c doesn't work anymore as well
 }


Bug in the GC?

I suppose my question would be why you're generating that huge buffer
in memory instead of just writing it all out to the file in the first
place.  Use a std.stream.BufferedFile.
Jan 27 2009
parent "Saaa" <empty needmail.com> writes:
 Bug in the GC?

 I suppose my question would be why you're generating that huge buffer
 in memory instead of just writing it all out to the file in the first
 place.  Use a std.stream.BufferedFile.


Because it just needed to work and I have no experience with streams.. :/
And, writing it line by line was too slow (although I'm not sure anymore 
since it might be the same problem)
Jan 27 2009
prev sibling next sibling parent reply Alan Turing <at bletchley.park.uk> writes:
Maybe I can help...


Saaa Wrote:


 My program doesn't exit..
 
 void main()
 {
 
 ..
 Data data[]
 
 createData(data);
 //This proces takes a minute or two.
 //data now holds about 700000 Data elements
 
  writefln(`Creating buffer`);
  ubyte[] buffer;
  for (int i=0; i<data.length; i++)
  {
   buffer~=format(data[i].net,`,`,data[i].name,`,`,to!(int[])(data[i].output),`,`,to!(int[])(data[i].input),newline);
   //This takes like a minute and has a peak memory usage of 680MB
  }
 
  writefln(`Writing file`);
  std.file.write(outFilename, buffer);
 writefln(`Writing file finished`);
 
 //The file is readily made and delta memory usage shows a few a few times 
 around 20MB
 //but the program doesn't stop, although 'Writing file finished' is shown.
 //there is no static this or alike.
 //and after 10 minutes the memory usage is about 370MB and slowly going up
 //ctrl-c doesn't work anymore as well
 }
Jan 27 2009
next sibling parent Daniel Keep <daniel.keep.lists gmail.com> writes:
Alan Turing wrote:

 Maybe I can help...


At first glance, this might look like someone being silly and not at all
helpful... but in truth, Mr. Turing has probably already fixed your
source code with his incredible powers.  If you notice your firewall has
melted into a pile of slag, and your PC seems to be running a lot
faster, that'd be him.

Most people seem to think he's dead; this is only partially true.
Whilst his physical body died, his mind lives on in the Internet, ever
vigilant to ensure the safe delivery of our daily LOLCATs.

Some other random Alan Turing facts:

* The only reason Alan Turing hadn't solved the halting problem is that
it was too busy running from him in fear.
* Alan Turing could tell what a RAM chip contains simply by smelling it.
* Alan Turing programmed computers in raw machine code, using a
magnetised pin.
* Alan Turing didn't bother programming; he just stared at a computer
until it submits to his will.
* Alan Turing only designed the bombe because "he just stared at
ciphertexts for 10 seconds and wrote down the plaintext" wouldn't make
for an interesting documentary 70 years later.
* Steve Ballmer lives in perpetual fear of the day Alan Turing will
return to unmake Microsoft.
* When Alan Turing crashes a machine, all the other machines on the same
subnet dump core out of fear.
* Alan Turing can break RSA encryption up to 4096 bits; he doesn't
bother because it's not challenging enough.
* Alan Turing knows what you were browsing last summer.

  -- Daniel "insomnia is a terrible thing..." Keep
Jan 27 2009
prev sibling parent Jarrett Billingsley <jarrett.billingsley gmail.com> writes:
On Tue, Jan 27, 2009 at 11:04 AM, Alan Turing <at bletchley.park.uk> wrote:

 Maybe I can help...


Looool.
Jan 27 2009
prev sibling next sibling parent BCS <ao pathlink.com> writes:
Reply to Saaa,


 My program doesn't exit..
 
 void main()
 {
 ..
 Data data[]
 createData(data);
 //This proces takes a minute or two.
 //data now holds about 700000 Data elements
 writefln(`Creating buffer`);
 ubyte[] buffer;
 for (int i=0; i<data.length; i++)
 {
 
 buffer~=format(data[i].net,`,`,data[i].name,`,`,to!(int[])(data[i].out
 put),`,`,to!(int[])(data[i].input),newline);


~= in a short loop is a really bad thing. It will tend to need twice the 
ram you really needed and hammers the GC. Also if you start getting false 
pointers it gives them lots of memory segments to land in.


 //This takes like a minute and has a peak memory usage of 680MB
 }
 writefln(`Writing file`);
 std.file.write(outFilename, buffer);
 writefln(`Writing file finished`);
 //The file is readily made and delta memory usage shows a few a few
 times
 around 20MB
 //but the program doesn't stop, although 'Writing file finished' is
 shown.
 //there is no static this or alike.
 //and after 10 minutes the memory usage is about 370MB and slowly
 going up
 //ctrl-c doesn't work anymore as well
 }
Jan 27 2009
prev sibling parent reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
"Saaa" wrote

 My program doesn't exit..


Have you tried a debugger, breaking into the program when it is hanging to 
find out where it is?

-Steve
Jan 27 2009
parent reply "Saaa" <empty needmail.com> writes:
No, normally writefln suffices.. :)
btw. Why do writef writes not always show up at the expected places?


 Have you tried a debugger, breaking into the program when it is hanging to 
 find out where it is?

 -Steve
Jan 27 2009
next sibling parent Jarrett Billingsley <jarrett.billingsley gmail.com> writes:
On Tue, Jan 27, 2009 at 5:33 PM, Saaa <empty needmail.com> wrote:

 No, normally writefln suffices.. :)
 btw. Why do writef writes not always show up at the expected places?


If you mean that sometimes you write something but it never shows up,
it's because it buffers the output.  You have to use fflush(stdout) to
see the output immediately.

Unless you mean something else.  <_<
Jan 27 2009
prev sibling next sibling parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
"Saaa" wrote

 No, normally writefln suffices.. :)
 btw. Why do writef writes not always show up at the expected places?


It's tough to insert writefln's after main exits :)  That's probably where 
your code is hanging (seeing as how your final message is successfully 
printed).

And to answer your second question, writef and writefln use C's FILE * 
interface I believe underneath, which is set to flush only on a newline 
being written.  If you want to flush even when a newline is not written, use 
fflush(stdout).

-Steve
Jan 27 2009
prev sibling parent "Saaa" <empty needmail.com> writes:
Thanks..
I think I need to start using that debugging thing..
Jan 27 2009