thread.abort and thread.suspend

[am]

Hi to all.
I have a little problem. I'm working with threads, and I need to abort
or suspend them, but many experts dissuade from use Thread.Abort and
Thread.Suspend. As I didn't find other way, how can I do?
Thanks a lot!

[Lasse Vågsæther Karlsen]

Re: thread.abort and thread.suspend

am wrote:[color=blue]
> Hi to all.
> I have a little problem. I'm working with threads, and I need to abort
> or suspend them, but many experts dissuade from use Thread.Abort and
> Thread.Suspend. As I didn't find other way, how can I do?
> Thanks a lot!
>[/color]

Usually you're suspending the thread in order to wait for something to
do and to do that you're better off using one of the synchronizing
objects (like the event objects) and wait for the events to become
signalled.

As for aborting a thread, that has a whole host of problems associated
with it (with Thread.Abort that is) and a better way is to look at an
event object to become signalled and then simply return from the thread
method.

--
Lasse Vågsæther Karlsen

http://www.vkarlsen.no/

mailto:lasse@vk arlsen.no
PGP KeyID: 0x2A42A1C2

[SharpCoderMP]

Re: thread.abort and thread.suspend

hi,

i had this issue with aborting thread:
my separate thread was generating bitmap thumbnails from larger bimap
files. when i was aborting this thread it sometimes happened that bitmap
objects were not disposed immediately, so i ended up with 200-300 megs
of memory ussage.
someone suggested that i should create some sort of stop signal value
which is frequently checked by the thread. if the value is set to true
then thread skips all its job and exits.
this works well but has one problem - if operation performed by thread
is very time consuming, like reading or writing large files or
resampling bimaps *AND* this is done in one line of code, then you cant
cancel this operations with metioned stop signal. so you may end up
waiting for the operation to finish. offcourse with stop signal you end
up with clean exit (you can free all resources), but you cant cancel a
single operation this way.
and for that i didn't found a sollution :(

am wrote:[color=blue]
> Hi to all.
> I have a little problem. I'm working with threads, and I need to abort
> or suspend them, but many experts dissuade from use Thread.Abort and
> Thread.Suspend. As I didn't find other way, how can I do?
> Thanks a lot!
>[/color]

[Ignacio Machin \( .NET/ C# MVP \)]

Re: thread.abort and thread.suspend

Hi,

Take a look at Skeet's article :

http://www.yoda.arachsys.com/csharp/threads/abort.shtml

cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation


"am" <am_public@emai l.it> wrote in message
news:1125652034 .158916.170530@ g43g2000cwa.goo glegroups.com.. .[color=blue]
> Hi to all.
> I have a little problem. I'm working with threads, and I need to abort
> or suspend them, but many experts dissuade from use Thread.Abort and
> Thread.Suspend. As I didn't find other way, how can I do?
> Thanks a lot!
>[/color]

[am]

Re: thread.abort and thread.suspend

Thanks a lot to all!
Now I will post my solution. If you find something wrong tell me
please. Thanks a lot again.

class Engine
{

private ManualResetEven t mResetEvent = new ManualResetEven t( true );
private volatile bool mStopExecution;

protected bool StopExecution
{
get { return mStopExecution; }
}

/// <summary>
/// Stops as soon as possible
/// </summary>
protected internal void Stop()
{
mStopExecution = true;

// restart thread in case it was suspended before stop request
Restart();
}

/// <summary>
/// Suspends thread
/// </summary>
protected internal void Suspend()
{
// set the monitor to not segnaled if thread is not requested to stop
if ( !StopExecution )
mResetEvent.Res et();
}

/// <summary>
/// Restart suspended thread
/// </summary>
protected internal void Restart()
{
// segnales monitor
mResetEvent.Set ();
}

/// <summary>
/// This is the function used as argument of new ThreadStart() in the
constractor of
/// new Thread
/// </summary>
protected internal void Start( )
{
try
{
ExecControl();
}
catch ( Exception ecc )
{
mExitStatus = ExitStatusType. Errors;
mError = ecc;
}
finally
{
Done();
}
}

/// <summary>
/// Looks for suspend or stop requests.
/// </summary>
protected bool VerifySuspendSt op()
{
bool continueExecuti on = true;

TimeSpan timeout = new TimeSpan( 3, 0, 0 );

if ( !mResetEvent.Wa itOne( timeout, false ) )
{
mResults = "Timeout occured.";
continueExecuti on = false;
mExitStatus = ExitStatusType. TimeoutSuspend;
}
else if ( StopExecution )
{
mResults = "Thread stopped by user";
continueExecuti on = false;
mExitStatus = ExitStatusType. Stopped;
}

return continueExecuti on;
}

/// <summary>
/// Here I do what I want.
/// </summary>
protected void ExecControl()
{
while( VerifySuspendSt op )
{
// quick code

if ( !VerifySuspendS top )
{
return;
}

// time consuming code

if ( !VerifySuspendS top )
{
return;
}

// time consuming code
}
}

}

class ClassThatUsesEn gine
{
public ClassThatUsesEn gine()
{
Engine engine = new Engine();

Thread thread = new Thread( new ThreadStart( engine.Start ) );

thread.Start();

thread.Join();
}
}