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Re: multi threaded script

On Tuesday 03 November 2009 17:34:57 Baptiste Daroussin wrote:
> Hi,
> I wanted to write a script that needs to be multithreaded, for example
> an UI in zsh/curses that does things in background while the UI is
> still responsive.

It's possible to do background tasks in subshells. Simple append an & to 
the end of the subshell list:

  print "hi_0"; { print "hi_1"; sleep 60; print "hi_2"} & print "hi_3"; \
     sleep 20; print "hi_4"

Somewhere on the internet there is an example in bash of how to setup a 
multiprocess shell program which uses subshells as worker processes. The 
communication between these processes is done via named pipes. It's much 
like Apache's worker process model.

Here is a simple and quick suggestion how such an architecture may look 
like in zsh:


worker() {
    while (true) {
        print "job started: $1"

        read -u 0
        eval "$REPLY"

        print "job done: $1"

mkfifo pipe
worker "worker 0" < pipe &  workers+=($!)
worker "worker 1" < pipe &  workers+=($!)

print "sleep 20" >> pipe
print "sleep 30" >> pipe
print "sleep 5; ls; sleep 5" >> pipe
sleep 20
print "sleep 20" >> pipe

print "exit\nexit" >> pipe

wait ${workers[*]}
rm pipe
exit 0

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