threads-communication.tcl -- simplest example how workers can communicate with master

threads-communication.tcl

# task params for all threads
tsv::array set params {one 1 two 2}

# worker task:
set th_task {
  if {[catch {
    # do some work (here sum of params):
    set res [expr {[tsv::get params one] + [tsv::get params two]}]
    # provide result to master:
    thread::send -async $master [list lappend th_res $res]
  } msg]} {
    puts stderr "worker [thread::id] failed:\n $::errorInfo"
  }
}

# main thread:
set th_res {}
foreach i {0 1 2 3} {
  set t($i) [thread::create]; 
  # provide a master ID to thread:
  thread::send -async $t($i) [list set master [thread::id]]
  # send job to threads:
  thread::send -async $t($i) $th_task
}

# wait for result from all 4 threads:
while {[llength $th_res] < 4} {
  vwait th_res
}

# ready:
puts "results: $th_res"

# release threads:
foreach i {0 1 2 3} {
  catch { thread::release -wait $t($i) }
}