Tcl 线程：如何在线程中访问全局变量

Question

我有一个名为“startMyProc {num}”的过程。我希望这个 proc 被两个不同的线程调用并等待两个线程完成。我尝试了给出的有效解决方案。我想访问 startMyProc 中的全局变量并调用另一个过程“startMyAnotherProc {num}”。如何才能做到这一点？

package require Thread


global myVar

set myVar false

set id1 [thread::create -joinable {
    source sample.tcl
    thread::wait
    }]
set id2 [thread::create -joinable {
    source sample.tcl
    thread::wait
    }]

set num 1
thread::send -async $id1 [list startMyProc $num]
set num 2
thread::send -async $id2 [list startMyProc $num]

thread::join $id1
thread::join $id2

My sample.tcl looks like this,

proc startMyProc { num } {
    global myVar
    puts $myVar
    puts "Opening $num"
    after 2000
    puts "Opening $num"
    after 2000
    puts "Opening $num"
    after 2000
    startMyAnotherProc $myVar
    return
}

proc startMyAnotherProc { num } {
    puts "Opening Another Proc: $num"
    after 2000
    puts "Opening Another Proc: $num"
    after 2000
    return
}

Answer 1

每个线程都有自己完整的解释器，与程序中的所有其他解释器隔离（thread包的命令功能除外）。在所有线程中获取过程的最简单、最直接的方法是将它放在一个脚本文件中，然后source作为线程启动脚本的一部分：

set t1 [thread::create -joinable {
    source myProcedures.tcl
    startMyProc $num
}]
set t2 [thread::create -joinable {
    source myProcedures.tcl
    startMyProc $num
}]

不过你会遇到另一个问题。变量也不能共享。这意味着你不会克服$num。你真的应该让脚本启动然后thread::wait在最后做。然后，您可以thread::send完成工作（并在构建脚本时获得正确的替换）。

set t1 [thread::create -joinable {
    source myProcedures.tcl
    thread::wait
}]
set t2 [thread::create -joinable {
    source myProcedures.tcl
    thread::wait
}]
thread::send -async $t1 [list startMyProc $num]
thread::send -async $t2 [list startMyProc $num]

但是，如果您真的考虑将任务发送到工作线程，则应该查看线程池 ( tpool) 支持；这是很多以扩大更容易。

# Make the thread pool
set pool [tpool::create -initcmd {
    source myProcedures.tcl
}]

# Sent the work into the pool as distinct jobs
set job1 [tpool::post $pool [list startMyProc $num]]
set job2 [tpool::post $pool [list startMyProc $num]]

# Wait for all the jobs in the pool to finish
set waitingfor [list $job1 $job2]
while {[llength $waitingfor] > 0} {
    tpool::wait $pool $waitingfor waitingfor
}

# Get results now with tpool::get

# Dispose of the pool
tpool::release $pool