ns_thread(3aolserver)					    AOLserver Built-In Commands 				     ns_thread(3aolserver)

__________________________________________________________________________________________________________________________________________________

NAME

       ns_thread - commands

SYNOPSIS

       ns_thread begin script

       ns_thread begindetached script

       ns_thread get

       ns_thread getid

       ns_thread wait tid

       ns_thread yield
_________________________________________________________________

DESCRIPTION

       ns_thread begin:
	      begins  a  new  thread which evaluates the specified script and then exits. It returns a thread ID that must eventually be passed to
	      ns_thread wait. (Failing to call ns_thread wait will eventually result in no new threads being created.)

       ns_thread begindetached:
	      begins a detached thread that doesn't have to be (and can't be) waited for.

       ns_thread get:
	      gets the thread ID of the current thread. The result is a thread ID that can be passed to ns_thread wait and may look something like
	      "tid532".

       ns_thread getid:
	      gets  the  thread integer number for the current thread. The result is a small integer used for identifying threads is a human-read-
	      able way, such as "1" or "1120", for example.

       ns_thread wait:
	      waits for the specified thread to exit. The tid argument is a thread ID returned by ns_thread begin or ns_thread get.

       ns_thread yield:
	      causes the current thread to yield.

EXAMPLES

       This example is similar to the example under the ns_sockselect function of connecting to the 10 servers and waiting to  service	them  with
       the ns_sockselect command. In this case, though, each connection gets it's own thread.

       # This is the procedure which is evaluated for each thread and # handles a single connection to host number $i

       proc getpage {i} {
	   global pages
	   # new thread will start here - first connect to host
	   set host [format "www%2d.foo.com" $i]
	   set fds [ns_sockopen $host 80
	   set r [lindex $fds 0]
	   set w [lindex $fds 1]
	   # next, send request 	   0r"
	   puts $w "GET /index.htm HTTP/1.0
	   flush $w
	   # then read page
	   set pages($i) [read $r]
	   # and close sockets
	   close $w
	   close $r
	   # thread goes away here and other threads waiting
	   # on ns_thread wait will wakeup }

       # Here's the loop which creates the threads which run getpage.  for {set i 1} {$i < 9} {incr i} {
	   set tids($i) [ns_thread begin "getpage $i"] }

       # wait for the threads to exit and then process the pages for {set i 1} {$i < 9} {incr i} {
	   ns_thread wait $tids($i)
	   # output page
	   ... process the page in $pages($i) put there by other thread ...  }

       Note that the code here is much simpler to follow than the ns_sockselect example; that's the benefit of multithreaded programming. However,
       it uses more resources as threads need to be created and initialized. This can be a problem if you plan to create many threads.

SEE ALSO

KEYWORDS

       threads

AOLserver								4.0						     ns_thread(3aolserver)