Event logging into a single textfile by more than one users at a time

[jaleel]

Hi ,
i would like to reopen the issue in the post http://www.gamedev.net/community/for...opic_id=418791.

My scenario is like this:

1. A web application is there (being created by some other company)

2. We develop the business layer and data access layer.


The web application calls our business class. Our business class in turn calls stored procedures and all and giving back result to web application.Now , Our business class uses a commonservice class which contains the code for logging, exception handling and all.

The problem is when we log execution information of our business class to a single location,say D:\logfile\logg ing.txt.When more than one user accesses the
the same file, some contention happens. Not all events are logged by all users.

To avoid this I wrote a new class for logging and added to commonservice class , which looks like:

Imports System.IO
Public Class MyTextwriter
 
 
    Private tw As System.IO.TextWriter
 
 
    Public ReadOnly Property MyTextwriter() As System.IO.TextWriter
        Get
 
            tw = System.IO.TextWriter.Synchronized(File.AppendText("D:\log\temp.txt"))
 
 
            Return tw
        End Get
    End Property
 
 
 
 
Public Sub Trace(ByVal message As String)
 
          tw = MyTextwriter
 
 
        tw.Write(message)
        tw.Flush()
        tw .Close()
 
    End Sub 'Trace 
 
 
 
 
End Class
 

I tried testing this new logging class using a .net multithreaded application
which spawns 20 threads and each executes our business class method(which does all our business logic ) which in turn calls our logging class for logging the events to the same file at a time. But the problem still persist, an exception is thrown saying like:"The file D:\logfile\logg ing.txt is being used by some other process" .

Can anybody help me to solve this issue? Any ideas, hints, and help would be greatly appreciated..


Thanks.
jaleel

[Shashi Sadasivan]

Since the file can be read by only onbe process at a time
the best approach would be to funnel all the processes into one!!

A static / singleton class would do the magic.

Cheers

[Plater]

Yeah, easy pie.
Use a static class.

Pretty much all of my projects now have a static class called "Logging"
I keep various methods to log data, log errors and to log anything I else I want.

[jaleel]

i thank u for ur reply..

I wil give it a try tomorrow as I'm on leave 2day.

I am really afraid that making the logging class as static will alone manage all
race conditions happenening when more than one threads are trying to log to the same file.Anyhow I will try with it and get back u with comments...

thanks ,jaleel

[Shashi Sadasivan]

i thank u for ur reply..

I wil give it a try tomorrow as I'm on leave 2day.

I am really afraid that making the logging class as static will alone manage all
race conditions happenening when more than one threads are trying to log to the same file.Anyhow I will try with it and get back u with comments...

thanks ,jaleel

A static class will always maintain only one instance in the application.
So even if 2 threads attack the static class at almost the same time it will form a queue, So logging will be as normal.

Cheers

[jaleel]

Hi
i tried using a class with static members , but not worked well. But following code works fine for some extent.

Public Class Logger
 
 
 
Private loggingTimeStamp As DateTime 'non-static members 
 
Private messageLog As String
 
Private loggingFile As String
 
Private exceptionMessage As String
 
Private Shared tw As System.IO.TextWriter ' static variable
 
Private Shared locker As New Object
 
Public Sub Trace(ByVal message As String)
 
SyncLock locker
 
Try
 
 
messageLog = message + DateTime.Now.ToString
 
.......................................
 
'here some other manipulation like if logginfile is > 2MB rename it to some other name
 
'can I put the part till the next statement ( i.e. initialising textwriter )outside the locker?
 
tw = System.IO.TextWriter.Synchronized(File.AppendText(loggingFile))
 
 
tw.WriteLine(messageLog)
 
tw.Flush()
 
 
Catch
 
exceptionMessage = "LoggingFileError"
 
Throw New Exception(exceptionMessage)
 
Finally
 
tw.Close()
 
 
End Try
 
End SyncLock
 
End Sub 'Trace 
 
End Class

it works fine with 20 threads. But i tested using 50 threads and 100 threads . but some cases failed to log correctly say 2 to 10 cases . Theses amount of threads are not able to debug at a time. What could be the problem.. any suggestions?

Could anybody show some sample class which works fine..?

thanks in advance,
jaleel

[Shashi Sadasivan]

Though this wouldnt help much but try making your classs a static one too.

If you still have issues follow the singleton pattern correctly and it should perform better

cheers

[jaleel]

hi shashi ,i think there is no static(i.e.shar ed) class in vb.net. Singleton means having only one object..right? need to try it.

thanks

[Shashi Sadasivan]

hi shashi ,i think there is no static(i.e.shar ed) class in vb.net. Singleton means having only one object..right? need to try it.

thanks

Wow...is it?
C# Rulez :P
hahaha..well... there must be, try some online convertor to test it

if not i will try it tomorrow!

cheers

[dip_developer]

Wow...is it?
C# Rulez :P
hahaha..well... there must be, try some online convertor to test it

if not i will try it tomorrow!

cheers

Hi sashi......

vb.net also rulez as c#......there is Static class in VB.Net also......but the implementation is different....VB has an object named Module....you can add a module to your project and can write your Methods there....Module is a static class and doesn't need to be instantiated........

you can have a mudule named myGlobalModule and can access a method of that module named myGlobalMethod by simply writing
myGlobalModule.myGlobalMethod( ).

As far my knowledge goes....

Although differences do exist between VB and C#, both languages use the .NET Framework common language runtime and are equally powerful