[Tcl-bugs] [ tcl-Bugs-1306694 ] Sockets are not working in the child processes

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Bugs item #1306694, was opened at 2005-09-28 02:32
Message generated for change (Comment added) made by hobbs
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Category: 24. Channel Commands
Group: current: 8.4.11
>Status: Closed
Resolution: None
Priority: 5
Submitted By: Ravi Shankar. B (rbalakri)
Assigned to: Andreas Kupries (andreas_kupries)
Summary: Sockets are not working in the child processes

Initial Comment:
When a process is forked and if socket is executed
within the child process the socket is not accepting
the incoming connection.

Tcl version: 8.4.11
Platform: Linux

Tcl Version is compiled with threading enabled. The
following is the sample server (daytime server) program
to reproduce the problem,

proc Server {channel clientaddr clientport} {
   puts "Connection from $clientaddr registered"
   puts $channel [clock format [clock seconds]]
   sleep 30
   close $channel
}

if { [fork] } {
       # Parent
        wait
        exit
} else {
       # child
        socket -server Server 9900
        puts "child waiting for sockets"
        vwait forever
}

The corresponding client program,

set server localhost
set sockChan [socket $server 9900]
gets $sockChan line
close $sockChan
puts "The time on $server is $line"

After the server is started and after starting the
client netstat comman gives the following output,

[root@myhost test]# netstat -atp | grep 9900
tcp        0      0 *:9900                      *:*   
                     LISTEN      4309/tcl
tcp        0      0 myhost:36222          myhost:9900 
         ESTABLISHED 4291/tcl
tcp        0      0 myhost:9900           myhost:36222
         ESTABLISHED -

The first one is the server's listening socket, second
is clients socket and third is server's connected
socket. As you can see the sever's socket doesn't have
the application associated with it.

----------------------------------------------------------------------

>Comment By: Jeffrey Hobbs (hobbs)
Date: 2005-09-28 10:57

Message:
Logged In: YES 
user_id=72656

Fork and threads are not a valid combination.  If you have a
threaded build, please use another thread, not fork.

----------------------------------------------------------------------

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