Visual Basic

23-Jun-09 22:50

hi all

i am working on a multi threaded app

now in app, 5 or more threads have to write thousands of lines in a text file simultanously
i know this kills the cpu but no prob there

i have the lines to be written in an static array (I think static makes the process faster.is it true?)

my code:

For co% = 0 To (strarray.length - 1)
writer.WriteLine(strarray(co))
Next

where writer is StreamWriter
i do the flush close etc

my prob is that all files are not being written
if array has 25000 elements then
sometimes only 10000 or sometimes 15000 are written

should i try a timer instead of loop?
if not kindly suggest someother means.

TheMrProgrammer

Christian Graus23-Jun-09 23:06

23-Jun-09 23:06

TheMrProgrammer wrote:
i know this kills the cpu but no prob there

No, it kills the file if multiple threads try to write to it.

TheMrProgrammer wrote:
(I think static makes the process faster.is it true?)

No. Seems like you have no idea what you're doing.

TheMrProgrammer wrote:
sometimes only 10000 or sometimes 15000 are written

Because your different threads are going to clash. Try using one thread, given that your array is static, the data is always the same, so having 5 threads trying to write the same file, is kind of retarded, right ?

Christian Graus

Driven to the arms of OSX by Vista.

"! i don't exactly like or do programming and it only gives me a headache." - spotted in VB forums.

I can do things with my brain that I can't even google. I can flex the front part of my brain instantly anytime I want. It can be exhausting and it even causes me vision problems for some reason. - CaptainSeeSharp

Jon_Boy24-Jun-09 1:31

Jon_Boy

24-Jun-09 1:31

LOL - so blunt.

"There's no such thing as a stupid question, only stupid people." - Mr. Garrison

TheMrProgrammer24-Jun-09 4:25

24-Jun-09 4:25

sorry
i forgot to mention that all the threads write to separate files.

now suggest some means

TheMrProgrammer

Christian Graus24-Jun-09 10:41

24-Jun-09 10:41

Your data source is static. I presume your problem is still that you have threads writing files as the data is being filled. Overall, it sounds insane to me.

If you're saying that some of the data in the middle does not get written, then I assume this means that your problem is still one of concurrency. Why do you have 5 threads all writing at once ? do they write to the same HDD ?

TheMrProgrammer24-Jun-09 19:51

24-Jun-09 19:51

hi christian

my program is a file searching utility
i have made a class SEARCHER which goes to all directories and gets the
files that match the search string.

i wanted to index all files present in HDD
so i made an array of SEARCHER with size = all drives and call it using *.* as search string. all members are called in a separate thread so as to do all
drives at once

i have added a list box which displays the found files.
then i iterate through all items of listbox writing them one by one

I have dropped the static arrays

but the prob persists. if total items are 25000
then only top 15000 or 10000 are being written

Christian Graus wrote:
you have threads writing files as the data is being filled

no when the list box is filled then only the writing starts

Christian Graus wrote:
do they write to the same HDD ?

yes they write to the same HDD

Christian Graus wrote:
Why do you have 5 threads all writing at once ?

to write more in less time.The no of threads depend on the number of drives that are ready.

i also tried running a single thread.
in it also, only some files of top are being written.

TheMrProgrammer

Luc Pattyn24-Jun-09 13:34

Luc Pattyn

24-Jun-09 13:34

Hi,

you failed to clearly tell us what you are doing. Writing data, any data, to different files, using one thread per file, can be done correctly, which does not mean it always makes sense. If you want detailed help, show us some code (in PRE tags!) for two of those threads and files.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

DISCLAIMER: this message may have been modified by others; it may no longer reflect what I intended, and may contain bad advice; use at your own risk and with extreme care.

TheMrProgrammer24-Jun-09 19:55

24-Jun-09 19:55

hi Luc
please read my reply to Christian

TheMrProgrammer

Luc Pattyn24-Jun-09 23:29

Luc Pattyn

24-Jun-09 23:29

Hi,

you didn't show any code, at least you explained a bit.
"so i made an array of SEARCHER with size = all drives and call it using *.* as search string" is ambiguous; at best you have a double risk:
1. the number of files returned by GetFiles/GetDirectories could be huge, you may run out of memory
2. you may encounter "access denied" problems on special folders such as "System Volume Information".

Both of these would show up if you were using try-catrch blocks showing all available exception information, i.e. using Exception.ToString(); qnd everything would vanish silently if you are just swallowing exceptions.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

DISCLAIMER: this message may have been modified by others; it may no longer reflect what I intended, and may contain bad advice; use at your own risk and with extreme care.

TheMrProgrammer25-Jun-09 3:37

25-Jun-09 3:37

thamks for your suggestions Luc
but my problem is that out of 25000 files in the
list box only top 15000 or 10000 are being written

i tried putting the contents of the list box in a string variable
but without success

For x = 0 to listbox1.Items.Count-1
strVar &= listbox1.Items(x).ToString
Next
my.comp.filesystem.writealltext(filepath,strVar)

but instead "#ERROR 488# is written

TheMrProgrammer

Hexadecimal const declare

Luc Pattyn25-Jun-09 3:51

Luc Pattyn

25-Jun-09 3:51

TheMrProgrammer wrote:
For x = 0 to listbox1.Items.Count-1
strVar &= listbox1.Items(x).ToString
Next

for counts of many tenthousands, this is non-seense: the final result would probably be a string with a length exceeding one million characters, however building it also creates tenthousands of intermediate strings of growing length, so your code is bound to be extremely slow, and may well run out of memory.

furthermore, there was no need whatsoever to concatenate everything, since File class also has a WriteAllLines() method, which takes an array of strings.

finally, if you do not absolutely need to hold lots of data in memory, then don't. Just write the text lines as you get them. I know you are failing here so far, due to reasons unknown to all of us as you still haven't shown us real code. Lacking that, I will not continue this thread.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

DISCLAIMER: this message may have been modified by others; it may no longer reflect what I intended, and may contain bad advice; use at your own risk and with extreme care.

garfield18523-Jun-09 21:32

garfield185

23-Jun-09 21:32

Hi everybody

I must declare some constants on VB.NET based on some C code that I have, like this.

#define ABCDE_FGH 0x00008603L

How could I do this on VB.NET? I get an error doing this:

Public const ABCDE_FGH = 0x00008603L
Public const ABCDE_FGH 0x00008603L

And I'm afraid to use this:
Public const ABCDE_FGH = "0x00008603L", because although I don't get an error, it would be only text...

Does somebody know something about this?

Thanks everybody

Time to come clean...

Vive y deja vivir / Live and let live

Javier

Re: Hexadecimal const declare

Christian Graus23-Jun-09 21:38

Re: Hexadecimal const declare

23-Jun-09 21:38

garfield185 wrote:
Public const ABCDE_FGH = 0x00008603L

Did you read the error ? What does it say ?

You don't have a type, just access modifiers. Try public const int, and if that doesn't work ( I dunno if VB supports 0x for hex ), try converting it to a decimal number in calculator and put that.

JoeSharp23-Jun-09 22:03

JoeSharp

23-Jun-09 22:03

hi
visual basic does not support ox00008603L

try with:
Public Const ABCDE_FGH As Integer = &H00008603L
or
Public Const ABCDE_FGH As Long = &H00008603L

Re: Hexadecimal const declare

garfield18523-Jun-09 22:11

garfield185

23-Jun-09 22:11

Perfect.
Thanks both of you!

Time to come clean...

Vive y deja vivir / Live and let live

Javier

how to start a project

shivam jaitly23-Jun-09 21:32

shivam jaitly

23-Jun-09 21:32

i m making a project over bank management on vb.net but can't figure out where to start from

Christian Graus23-Jun-09 21:38

23-Jun-09 21:38

Click on file, then choose new, then choose project. From there, read the details of your homework, talk to your teacher if you are lost, and ask us if you have a specific question.

Dave Kreskowiak24-Jun-09 4:12

Dave Kreskowiak

24-Jun-09 4:12

Yeah, it usually starts with an interview process to gather the system requirements. It kind of helps to know what the application is expected to do, don't you think?

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Jon_Boy24-Jun-09 4:18

Jon_Boy

24-Jun-09 4:18

Sacrifice a virgin and drink goat blood? Seem absurd? So is this question.

"There's no such thing as a stupid question, only stupid people." - Mr. Garrison

scottgp24-Jun-09 5:24

scottgp

24-Jun-09 5:24

What do we do if he responds, "All set, what next"? Smile | :)