How can I check for thread existense ?

[fniles]

I am using VB.NET 2005. To check if the same program already run or not, I
can use the following

If Process.GetProc essesByName(Pro cess.GetCurrent Process.Process Name).Length

1 Then

MsgBox("Another instance of " & Process.GetCurr entProcess.Proc essName &
" is already running !")
End
End If

I am wondering if I can check the same thing for a thread.
I have 1 thread that I do not want to create multiple instances of. Can I
check whether the thread has exists before or not ?
Thank you.

[Spam Catcher]

Re: How can I check for thread existense ?

"fniles" <fniles@pfmail. comwrote in
news:#N7IxjN6HH A.600@TK2MSFTNG P05.phx.gbl:

I am wondering if I can check the same thing for a thread.
I have 1 thread that I do not want to create multiple instances of.
Can I check whether the thread has exists before or not ?
Thank you.

You would use a System Mutex to check if an instance is running. There
should be an example on google (used to be plenty, but I can't seem to find
one!!!)

But VB.NET 2005 already has an option to limit the application to one
instance...

[Michel Posseth [MCP]]

Re: How can I check for thread existense ?

Mutexes are normally used for detecting multiple instances of the same app

For threading you normally use the semaphore type

regards

michel


"Spam Catcher" <spamhoneypot@r ogers.comschree f in bericht
news:Xns99999EB 7D394Fusenethon eypotrogers@127 .0.0.1...

"fniles" <fniles@pfmail. comwrote in
news:#N7IxjN6HH A.600@TK2MSFTNG P05.phx.gbl:
>

>I am wondering if I can check the same thing for a thread.
>I have 1 thread that I do not want to create multiple instances of.
>Can I check whether the thread has exists before or not ?
>Thank you.

>
You would use a System Mutex to check if an instance is running. There
should be an example on google (used to be plenty, but I can't seem to
find
one!!!)
>
But VB.NET 2005 already has an option to limit the application to one
instance...
>

[fniles]

Re: How can I check for thread existense ?

Thank you.
What is semaphore type ?


"Michel Posseth [MCP]" <MSDN@posseth.c omwrote in message
news:u6FuuZO6HH A.2380@TK2MSFTN GP02.phx.gbl...

Mutexes are normally used for detecting multiple instances of the same app
>
For threading you normally use the semaphore type
>
regards
>
michel
>
>
"Spam Catcher" <spamhoneypot@r ogers.comschree f in bericht
news:Xns99999EB 7D394Fusenethon eypotrogers@127 .0.0.1...

>"fniles" <fniles@pfmail. comwrote in
>news:#N7IxjN6H HA.600@TK2MSFTN GP05.phx.gbl:
>>

>>I am wondering if I can check the same thing for a thread.
>>I have 1 thread that I do not want to create multiple instances of.
>>Can I check whether the thread has exists before or not ?
>>Thank you.

>>
>You would use a System Mutex to check if an instance is running. There
>should be an example on google (used to be plenty, but I can't seem to
>find
>one!!!)
>>
>But VB.NET 2005 already has an option to limit the application to one
>instance...
>>

>
>

[fniles]

Re: How can I check for thread existense ?

And how can I use the semaphore type to detect multiple instances of the
same thread ?

"Michel Posseth [MCP]" <MSDN@posseth.c omwrote in message
news:u6FuuZO6HH A.2380@TK2MSFTN GP02.phx.gbl...

Mutexes are normally used for detecting multiple instances of the same app
>
For threading you normally use the semaphore type
>
regards
>
michel
>
>
"Spam Catcher" <spamhoneypot@r ogers.comschree f in bericht
news:Xns99999EB 7D394Fusenethon eypotrogers@127 .0.0.1...

>"fniles" <fniles@pfmail. comwrote in
>news:#N7IxjN6H HA.600@TK2MSFTN GP05.phx.gbl:
>>

>>I am wondering if I can check the same thing for a thread.
>>I have 1 thread that I do not want to create multiple instances of.
>>Can I check whether the thread has exists before or not ?
>>Thank you.

>>
>You would use a System Mutex to check if an instance is running. There
>should be an example on google (used to be plenty, but I can't seem to
>find
>one!!!)
>>
>But VB.NET 2005 already has an option to limit the application to one
>instance...
>>

>
>

[Michel Posseth [MCP]]

Re: How can I check for thread existense ?

a thread can attempt to take ownership of the semaphore by calling the
waitone method , if the current count is higher as zero ( count of the
number of threads you allow ) , the semaphore returns inmediatly ,
otherwise it will wait until anoher thread releases the semaphore , or until
the optional timeout expires


here is an MSDN example

http://msdn2.microsoft.com/en-us/library/system.threading.semaphore.aspx

P.s.

remember to use a try finally block to ensure thet the semaphore is released
even if the code throws an exception

Like mutexes semaphores can have a name and be shared among processes when
you try to create a sempahore that already exists the initial and
maximumcounts are ignored


HTH

Michel



"fniles" <fniles@pfmail. comschreef in bericht
news:e3m28gZ6HH A.2208@TK2MSFTN GP06.phx.gbl...

And how can I use the semaphore type to detect multiple instances of the
same thread ?
>
"Michel Posseth [MCP]" <MSDN@posseth.c omwrote in message
news:u6FuuZO6HH A.2380@TK2MSFTN GP02.phx.gbl...

>Mutexes are normally used for detecting multiple instances of the same
>app
>>
>For threading you normally use the semaphore type
>>
>regards
>>
>michel
>>
>>
>"Spam Catcher" <spamhoneypot@r ogers.comschree f in bericht
>news:Xns99999E B7D394Fusenetho neypotrogers@12 7.0.0.1...

>>"fniles" <fniles@pfmail. comwrote in
>>news:#N7IxjN6 HHA.600@TK2MSFT NGP05.phx.gbl:
>>>
>>>I am wondering if I can check the same thing for a thread.
>>>I have 1 thread that I do not want to create multiple instances of.
>>>Can I check whether the thread has exists before or not ?
>>>Thank you.
>>>
>>You would use a System Mutex to check if an instance is running. There
>>should be an example on google (used to be plenty, but I can't seem to
>>find
>>one!!!)
>>>
>>But VB.NET 2005 already has an option to limit the application to one
>>instance...
>>>

>>
>>

>
>

[fniles]

Re: How can I check for thread existense ?

Thank you.
But, I have 2 different thread running on the application, and I would like
to allow those 2 threads only. They both have a different name, say
"ThreadA" and "ThreadB"
I only want 1 instance of "ThreadA" and 1 instance of "ThreadB"
Can I use semaphore to do that ?


"Michel Posseth [MCP]" <MSDN@posseth.c omwrote in message
news:eVngoya6HH A.1208@TK2MSFTN GP05.phx.gbl...

>a thread can attempt to take ownership of the semaphore by calling the
>waitone method , if the current count is higher as zero ( count of the
>number of threads you allow ) , the semaphore returns inmediatly ,
>otherwise it will wait until anoher thread releases the semaphore , or
>until the optional timeout expires
>
>
here is an MSDN example
>

http://msdn2.microsoft.com/en-us/library/system.threading.semaphore.aspx

>
P.s.
>
remember to use a try finally block to ensure thet the semaphore is
released even if the code throws an exception
>
Like mutexes semaphores can have a name and be shared among processes when
you try to create a sempahore that already exists the initial and
maximumcounts are ignored
>
>
HTH
>
Michel
>
>
>
"fniles" <fniles@pfmail. comschreef in bericht
news:e3m28gZ6HH A.2208@TK2MSFTN GP06.phx.gbl...

>And how can I use the semaphore type to detect multiple instances of the
>same thread ?
>>
>"Michel Posseth [MCP]" <MSDN@posseth.c omwrote in message
>news:u6FuuZO6H HA.2380@TK2MSFT NGP02.phx.gbl.. .

>>Mutexes are normally used for detecting multiple instances of the same
>>app
>>>
>>For threading you normally use the semaphore type
>>>
>>regards
>>>
>>michel
>>>
>>>
>>"Spam Catcher" <spamhoneypot@r ogers.comschree f in bericht
>>news:Xns99999 EB7D394Fuseneth oneypotrogers@1 27.0.0.1...
>>>"fniles" <fniles@pfmail. comwrote in
>>>news:#N7IxjN 6HHA.600@TK2MSF TNGP05.phx.gbl:
>>>>
>>>>I am wondering if I can check the same thing for a thread.
>>>>I have 1 thread that I do not want to create multiple instances of.
>>>>Can I check whether the thread has exists before or not ?
>>>>Thank you.
>>>>
>>>You would use a System Mutex to check if an instance is running. There
>>>should be an example on google (used to be plenty, but I can't seem to
>>>find
>>>one!!!)
>>>>
>>>But VB.NET 2005 already has an option to limit the application to one
>>>instance.. .
>>>>
>>>
>>>

>>
>>

>
>

[Spam Catcher]

Re: How can I check for thread existense ?

"fniles" <fniles@pfmail. comwrote in
news:eqZHu1m6HH A.5136@TK2MSFTN GP02.phx.gbl:

But, I have 2 different thread running on the application, and I would
like to allow those 2 threads only. They both have a different name,
say "ThreadA" and "ThreadB"
I only want 1 instance of "ThreadA" and 1 instance of "ThreadB"

Can you check the valud of the Thread Variable?

If ThreadA is Nothing then
'Do stuff here to initialize thread
Else
msgbox("Thread already created")
End if

[fniles]

Re: How can I check for thread existense ?

Yes, I can do that. Thank you.
I was thinking to check for it inside the thread itself.
Can I do that ?

"Spam Catcher" <spamhoneypot@r ogers.comwrote in message
news:Xns999B9E7 C9B548usenethon eypotrogers@127 .0.0.1...

"fniles" <fniles@pfmail. comwrote in
news:eqZHu1m6HH A.5136@TK2MSFTN GP02.phx.gbl:
>

>But, I have 2 different thread running on the application, and I would
>like to allow those 2 threads only. They both have a different name,
>say "ThreadA" and "ThreadB"
>I only want 1 instance of "ThreadA" and 1 instance of "ThreadB"

>
Can you check the valud of the Thread Variable?
>
If ThreadA is Nothing then
'Do stuff here to initialize thread
Else
msgbox("Thread already created")
End if

[Michel Posseth [MCP]]

Re: How can I check for thread existense ?


Yes you can do that by using 2 semaphores


"fniles" <fniles@pfmail. comschreef in bericht
news:eqZHu1m6HH A.5136@TK2MSFTN GP02.phx.gbl...

Thank you.
But, I have 2 different thread running on the application, and I would
like to allow those 2 threads only. They both have a different name, say
"ThreadA" and "ThreadB"
I only want 1 instance of "ThreadA" and 1 instance of "ThreadB"
Can I use semaphore to do that ?
>
>
"Michel Posseth [MCP]" <MSDN@posseth.c omwrote in message
news:eVngoya6HH A.1208@TK2MSFTN GP05.phx.gbl...

>>a thread can attempt to take ownership of the semaphore by calling the
>>waitone method , if the current count is higher as zero ( count of the
>>number of threads you allow ) , the semaphore returns inmediatly ,
>>otherwise it will wait until anoher thread releases the semaphore , or
>>until the optional timeout expires
>>
>>
>here is an MSDN example
>>
>http://msdn2.microsoft.com/en-us/lib...semaphore.aspx
>>
>P.s.
>>
>remember to use a try finally block to ensure thet the semaphore is
>released even if the code throws an exception
>>
>Like mutexes semaphores can have a name and be shared among processes
>when you try to create a sempahore that already exists the initial and
>maximumcount s are ignored
>>
>>
>HTH
>>
>Michel
>>
>>
>>
>"fniles" <fniles@pfmail. comschreef in bericht
>news:e3m28gZ6H HA.2208@TK2MSFT NGP06.phx.gbl.. .

>>And how can I use the semaphore type to detect multiple instances of the
>>same thread ?
>>>
>>"Michel Posseth [MCP]" <MSDN@posseth.c omwrote in message
>>news:u6FuuZO6 HHA.2380@TK2MSF TNGP02.phx.gbl. ..
>>>Mutexes are normally used for detecting multiple instances of the same
>>>app
>>>>
>>>For threading you normally use the semaphore type
>>>>
>>>regards
>>>>
>>>michel
>>>>
>>>>
>>>"Spam Catcher" <spamhoneypot@r ogers.comschree f in bericht
>>>news:Xns9999 9EB7D394Fusenet honeypotrogers@ 127.0.0.1...
>>>>"fniles" <fniles@pfmail. comwrote in
>>>>news:#N7Ixj N6HHA.600@TK2MS FTNGP05.phx.gbl :
>>>>>
>>>>>I am wondering if I can check the same thing for a thread.
>>>>>I have 1 thread that I do not want to create multiple instances of.
>>>>>Can I check whether the thread has exists before or not ?
>>>>>Thank you.
>>>>>
>>>>You would use a System Mutex to check if an instance is running. There
>>>>should be an example on google (used to be plenty, but I can't seem to
>>>>find
>>>>one!!!)
>>>>>
>>>>But VB.NET 2005 already has an option to limit the application to one
>>>>instance. ..
>>>>>
>>>>
>>>>
>>>
>>>

>>
>>

>
>