Hello. I am trying to split a file with 334,386 lines into seperate files of
50,000 each.
This is the code i am running:
Dim intFragmentRawI ndex As Integer
Dim swRawDataFile As StreamWriter
Dim intNewRawIndex As Integer
Dim strNewRawDataFi leName As String
Dim intFragmentCall Count As Integer = 0
Dim strHeaderLine As String
Dim blnFileClosed As Boolean = False
strHeaderLine = colRawDataFile( 1)
CreateRawDataFr agment(intParen tRawIndex, intNewRawIndex,
strNewRawDataFi leName)
Dim myFileStream As New
System.IO.FileS tream(strTempDi rectoryPath & strNewRawDataFi leName, _
FileMode.OpenOr Create, FileAccess.Writ e, FileShare.None)
swRawDataFile = New StreamWriter(my FileStream)
swRawDataFile.W riteLine(strHea derLine)
For i As Integer = 2 To colRawDataFile. Count
If intFragmentCall Count = 50000 Then
'Clear Stream Writer Buffer
swRawDataFile.F lush()
'Close file
swRawDataFile.C lose()
'Set Call Count against raw data file
SetFragmentCall Count(intNewRaw Index, intFragmentCall Count)
'Reset call count
intFragmentCall Count = 0
'If not on final line of raw data file....
If i <> colRawDataFile. Count Then
CreateRawDataFr agment(intParen tRawIndex,
intNewRawIndex, strNewRawDataFi leName)
myFileStream = New
System.IO.FileS tream(strTempDi rectoryPath & strNewRawDataFi leName, _
FileMode.OpenOr Create, FileAccess.Writ e, FileShare.None)
swRawDataFile = New StreamWriter(my FileStream)
swRawDataFile.W riteLine(strHea derLine)
Else
blnFileClosed = True
End If
End If
swRawDataFile.W riteLine(colRaw DataFile(i))
intFragmentCall Count += 1
Next
If Not blnFileClosed Then
'Close last fragment
swRawDataFile.C lose()
'Set call count against last fragment
SetFragmentCall Count(intNewRaw Index, intFragmentCall Count)
End If
The first file creates in 3 mins.
The second file creates in 11 minutes.
The third file creates in 18 minutes.
I am still waiting for the forth file to create.
I am writing the same number of records to each file, so why would the time
it takes to write the file of the same size take longer each time?
I thought that calling the flush method of the stream would maintain
performance but this does not seem to be the case! What am i doing wrong?
--
welcome to the mooon ! 10 3151
What are these routines :
- SetFragmentCall Count
- CreateRawDataFr agment
What is this variable :
colRawDataFile ...
??
>>SetFragmentCa llCount CreateRawData Fragment
Don't worry about these - basic database operations
colRawDataFil e
This is the key point in this routine - it's basically the entire file,
loaded into a collection - therefore, this collection has 334,386 entries in
it.
--
welcome to the mooon !
"olrt" wrote:
What are these routines :
- SetFragmentCall Count - CreateRawDataFr agment
What is this variable : colRawDataFile ...
??
Ok well i thought i'd try a different approach, so what I'm now trying is
appending 50,000 lines from the collection to a stringbuilder, and then
writing that entire stringbuilder to a file.
However, look at this log:
21/04/2006 14:09:06: Building String Start
21/04/2006 14:09:14: appended 10,000 lines to the stringbuilder
21/04/2006 14:09:39: appended 10,000 lines to the stringbuilder
21/04/2006 14:10:20: appended 10,000 lines to the stringbuilder
21/04/2006 14:11:20: appended 10,000 lines to the stringbuilder
21/04/2006 14:12:36: appended 10,000 lines to the stringbuilder
21/04/2006 14:12:36: append of 50,000 lines to file from stringbuilder
complete
21/04/2006 14:12:36: Building String Start
21/04/2006 14:14:05: appended 10,000 lines to the stringbuilder
21/04/2006 14:16:00: appended 10,000 lines to the stringbuilder
21/04/2006 14:18:36: appended 10,000 lines to the stringbuilder
21/04/2006 14:21:18: appended 10,000 lines to the stringbuilder
21/04/2006 14:23:58: appended 10,000 lines to the stringbuilder
21/04/2006 14:23:59: append of 50,000 lines to file from stringbuilder
complete
21/04/2006 14:23:59: Building String Start
I clear the stringbuilder between appending to the file using this code:
sbFileContent = New StringBuilder
However, there's still obviously a big slow down, why is this?
--
welcome to the mooon !
"m00nm0nkey " wrote: Hello. I am trying to split a file with 334,386 lines into seperate files of 50,000 each.
This is the code i am running:
Dim intFragmentRawI ndex As Integer Dim swRawDataFile As StreamWriter Dim intNewRawIndex As Integer Dim strNewRawDataFi leName As String Dim intFragmentCall Count As Integer = 0 Dim strHeaderLine As String Dim blnFileClosed As Boolean = False
strHeaderLine = colRawDataFile( 1)
CreateRawDataFr agment(intParen tRawIndex, intNewRawIndex, strNewRawDataFi leName)
Dim myFileStream As New System.IO.FileS tream(strTempDi rectoryPath & strNewRawDataFi leName, _
FileMode.OpenOr Create, FileAccess.Writ e, FileShare.None)
swRawDataFile = New StreamWriter(my FileStream)
swRawDataFile.W riteLine(strHea derLine)
For i As Integer = 2 To colRawDataFile. Count
If intFragmentCall Count = 50000 Then
'Clear Stream Writer Buffer swRawDataFile.F lush()
'Close file swRawDataFile.C lose()
'Set Call Count against raw data file SetFragmentCall Count(intNewRaw Index, intFragmentCall Count)
'Reset call count intFragmentCall Count = 0
'If not on final line of raw data file.... If i <> colRawDataFile. Count Then
CreateRawDataFr agment(intParen tRawIndex, intNewRawIndex, strNewRawDataFi leName)
myFileStream = New System.IO.FileS tream(strTempDi rectoryPath & strNewRawDataFi leName, _
FileMode.OpenOr Create, FileAccess.Writ e, FileShare.None)
swRawDataFile = New StreamWriter(my FileStream)
swRawDataFile.W riteLine(strHea derLine)
Else
blnFileClosed = True
End If
End If
swRawDataFile.W riteLine(colRaw DataFile(i))
intFragmentCall Count += 1
Next
If Not blnFileClosed Then
'Close last fragment swRawDataFile.C lose()
'Set call count against last fragment SetFragmentCall Count(intNewRaw Index, intFragmentCall Count)
End If
The first file creates in 3 mins. The second file creates in 11 minutes. The third file creates in 18 minutes. I am still waiting for the forth file to create.
I am writing the same number of records to each file, so why would the time it takes to write the file of the same size take longer each time?
I thought that calling the flush method of the stream would maintain performance but this does not seem to be the case! What am i doing wrong?
-- welcome to the mooon !
Not sure why you are using a StringBuilder to split a file into 3...
I would just read directly from the source file and would write to the
"current" file just switching to a new file when appropriate (just perhaps
playing with buffered streams to improve performance).
--
Patrice
"m00nm0nkey " <m0********@dis cussions.micros oft.com> a écrit dans le message
de news: 91************* *************** **...icrosof t.com... Ok well i thought i'd try a different approach, so what I'm now trying is appending 50,000 lines from the collection to a stringbuilder, and then writing that entire stringbuilder to a file.
However, look at this log:
21/04/2006 14:09:06: Building String Start 21/04/2006 14:09:14: appended 10,000 lines to the stringbuilder 21/04/2006 14:09:39: appended 10,000 lines to the stringbuilder 21/04/2006 14:10:20: appended 10,000 lines to the stringbuilder 21/04/2006 14:11:20: appended 10,000 lines to the stringbuilder 21/04/2006 14:12:36: appended 10,000 lines to the stringbuilder 21/04/2006 14:12:36: append of 50,000 lines to file from stringbuilder complete 21/04/2006 14:12:36: Building String Start 21/04/2006 14:14:05: appended 10,000 lines to the stringbuilder 21/04/2006 14:16:00: appended 10,000 lines to the stringbuilder 21/04/2006 14:18:36: appended 10,000 lines to the stringbuilder 21/04/2006 14:21:18: appended 10,000 lines to the stringbuilder 21/04/2006 14:23:58: appended 10,000 lines to the stringbuilder 21/04/2006 14:23:59: append of 50,000 lines to file from stringbuilder complete 21/04/2006 14:23:59: Building String Start
I clear the stringbuilder between appending to the file using this code: sbFileContent = New StringBuilder
However, there's still obviously a big slow down, why is this?
-- welcome to the mooon !
"m00nm0nkey " wrote:
Hello. I am trying to split a file with 334,386 lines into seperate files of 50,000 each.
This is the code i am running:
Dim intFragmentRawI ndex As Integer Dim swRawDataFile As StreamWriter Dim intNewRawIndex As Integer Dim strNewRawDataFi leName As String Dim intFragmentCall Count As Integer = 0 Dim strHeaderLine As String Dim blnFileClosed As Boolean = False
strHeaderLine = colRawDataFile( 1)
CreateRawDataFr agment(intParen tRawIndex, intNewRawIndex, strNewRawDataFi leName)
Dim myFileStream As New System.IO.FileS tream(strTempDi rectoryPath & strNewRawDataFi leName, _
FileMode.OpenOr Create, FileAccess.Writ e, FileShare.None)
swRawDataFile = New StreamWriter(my FileStream)
swRawDataFile.W riteLine(strHea derLine)
For i As Integer = 2 To colRawDataFile. Count
If intFragmentCall Count = 50000 Then
'Clear Stream Writer Buffer swRawDataFile.F lush()
'Close file swRawDataFile.C lose()
'Set Call Count against raw data file SetFragmentCall Count(intNewRaw Index, intFragmentCall Count)
'Reset call count intFragmentCall Count = 0
'If not on final line of raw data file.... If i <> colRawDataFile. Count Then
CreateRawDataFr agment(intParen tRawIndex, intNewRawIndex, strNewRawDataFi leName)
myFileStream = New System.IO.FileS tream(strTempDi rectoryPath & strNewRawDataFi leName, _
FileMode.OpenOr Create, FileAccess.Writ e, FileShare.None)
swRawDataFile = New StreamWriter(my FileStream)
swRawDataFile.W riteLine(strHea derLine)
Else
blnFileClosed = True
End If
End If
swRawDataFile.W riteLine(colRaw DataFile(i))
intFragmentCall Count += 1
Next
If Not blnFileClosed Then
'Close last fragment swRawDataFile.C lose()
'Set call count against last fragment SetFragmentCall Count(intNewRaw Index, intFragmentCall Count)
End If
The first file creates in 3 mins. The second file creates in 11 minutes. The third file creates in 18 minutes. I am still waiting for the forth file to create.
I am writing the same number of records to each file, so why would the time it takes to write the file of the same size take longer each time?
I thought that calling the flush method of the stream would maintain performance but this does not seem to be the case! What am i doing wrong?
-- welcome to the mooon !
>>> colRawDataFile This is the key point in this routine - it's basically the entire file, loaded into a collection - therefore, this collection has 334,386 entries in it.
And why do you load the entire file into a collection??? This doesn't
make sense to me (but maybe I don't have a complete understanding of
your solution)... I would try an approach like this (pseudo code):
FileReader input = ...;
FileWriter output = ...;
string data;
while (input is not EOF)
{
if (i = 50000)
{
// close old output
// create new output
}
output.write(in put.ReadLine()) ;
}
no need to fetch all lines into memory (a collection).
hth
Markus
m00nm0nkey <m0********@dis cussions.micros oft.com> wrote: SetFragmentCa llCount CreateRawData Fragment Don't worry about these - basic database operations colRawDataFil e
This is the key point in this routine - it's basically the entire file, loaded into a collection - therefore, this collection has 334,386 entries in it.
What kind of collection? If it's some kind of linked list, it would get
horribly slow.
Have you tried removing pieces of the routine (such as the database
operations) and seeing whether that makes a difference?
If this doesn't help, could you post a short but complete program which
demonstrates the problem?
See http://www.pobox.com/~skeet/csharp/complete.html for details of
what I mean by that. (Ignore the fact that it talks about C# - the same
can be done in VB.NET easily.)
If the database calls aren't the problem, then stripping those out to
produce a short but complete program shouldn't be an issue, and you can
generate random strings to put into the collection.
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
m00nm0nkey wrote: Hello. I am trying to split a file with 334,386 lines into seperate files of 50,000 each.
How about something along the lines of: read lines, one by one, write
them to current output. Every N lines open a new output.
void SplitIntoFiles( TextReader r, ulong limit, string nameFormat) {
ulong count = 0;
TextWriter w = null;
try {
for ( l = r.ReadLine(); l != null; l = r.ReadLine() ) {
if ( count % limit == 0 ) {
if ( w != null )
w.Dispose();
w = new TextWriter(stri ng.Format(forma t, count);
}
++count;
w.WriteLine(l);
}
} finally {
if ( w != null )
w.Dispose();
}
}
SplitIntoFiles( new TextReader(inpu t_path), 50000, input_path + ".{0}");
I haven't compiled the code, but you should be able to get the idea.
Note that the code above will add a newline to the end of the last
output-file, even if none was present in input_path. Also, the code will
not work as expected on files longer than ulong.Max lines.
--
Helge Jensen
mailto:he****** ****@slog.dk
sip:he********* *@slog.dk
-=> Sebastian cover-music: http://ungdomshus.nu <=-
Helge Jensen <he**********@s log.dk> wrote: Also, the code will not work as expected on files longer than ulong.Max lines.
When you find a disk capable of storing a file with
18,446,744,073, 709,551,615 lines, let me know :) At one byte per line,
that's still 16 exabytes. http://en.wikipedia.org/wiki/Exabyte has some interesting stats on
exabytes.
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
Jon Skeet [C# MVP] wrote: Helge Jensen <he**********@s log.dk> wrote:
Also, the code will not work as expected on files longer than ulong.Max lines.
When you find a disk capable of storing a file with 18,446,744,073, 709,551,615 lines, let me know :) At one byte per line, that's still 16 exabytes.
It's not that I'm concerned about it, it just happens to be so :)
Since some streams are infinite (or atleast supposed infinite) and line
oriented, it makes sense to just note the fact that there is a limit on
the expected behaviour.
The code could be rewritten to work on arbitrary-length input (provided
the FS allows arbitraty length paths) but I don't think it's worth the
effort, and it's nice to have the line-offset in the file-name so...
--
Helge Jensen
mailto:he****** ****@slog.dk
sip:he********* *@slog.dk
-=> Sebastian cover-music: http://ungdomshus.nu <=- This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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