vb.net - Activating timer from another thread -

so purpose of check connection of ftp server , if ftp enable timer1. i've read threads don't work synchonized , causing problem. without thread works fine, program hangs , stops responding constantly.

how can activate timer thread? maybe invoking , delegating work? don't know how that.

public function canportopen(byval hostname string, byval port integer) boolean     dim tcp new system.net.sockets.tcpclient     try         tcp.connect(hostname, port)     catch     end try     if tcp.connected = true         canportopen = true         tcp.close()         timer1.enabled = true     else         canportopen = false         tcp.close()         timer1.enabled = false         ftpup.abort()     end if end function  public sub checkconnection()     canportopen("hostname", port) end sub  private sub timer2_tick(sender object, e eventargs) handles timer2.tick     testftp = new system.threading.thread(addressof checkconnection)     testftp.isbackground = true     testftp.priority = threading.threadpriority.abovenormal     testftp.start() end sub  private sub timer1_tick(sender object, e eventargs) handles timer1.tick     ftpup = new system.threading.thread(addressof uploadtoftp)     ftpup.isbackground = true     ftpup.priority = threading.threadpriority.abovenormal     ftpup.start() end sub 

i think before start getting in deep threads should start looking @ backgroundworker component. can find on toolbar in designer , can drop on form. gives several events

dowork - hook event whatever want done in background thread

runworkercompleted - hook event run code in main (ui) thread, triggered when thread completes. code here can interact ui objects normal.

there other events allow report progress main thread, etc. purpose of backgroundworker component make simple multithreading tasks easier.

documentation -> here

see -> here examples of how pass data worker thread main thread using eventargs.

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alternatively, if want run timer thread can :

 'declare appropriate delegate  delegate sub dlgtimerenable(byval enable boolean)  'the delegate should match method signature  private sub timerenable(byval enable boolean)      timer1.enabled = enable  end sub 

and in thread procedure

public function canportopen(byval hostname string, byval port integer) boolean     dim tcp new system.net.sockets.tcpclient     try         tcp.connect(hostname, port)     catch     end try     if tcp.connected = true         canportopen = true         tcp.close()         me.invoke(new dlgtimerenable(addressof timerenable), new object() {true})     else         canportopen = false         tcp.close()         me.invoke(new dlgtimerenable(addressof timerenable), new object() {false})         ftpup.abort()     end if end function 

here invoke causes method executed on thread owns timer1 (assuming method in form me refer form). arguments passed object.

you can general way work timer, example :

delegate sub dlgtimerenable(byref tmr timer, byval enable boolean)  private sub timerenable(byref tmr timer, byval enable boolean)     tmr.enabled = enable end sub 

and :

me.invoke(new dlgtimerenable(addressof timerenable), new object() {timer1, true}) 

this makes delegate general - can pass timer , enable/disable it.