forks, ipc, fifos, update issues...


 
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Old 09-28-2005
forks, ipc, fifos, update issues...

Hi, so I've got this program("main") that fork executes another ("user"). These programs communicate through fifos.

One communication is a spawn call, where user passes an executable, main forks and executes it. So, I'm keeping track of all my processes using a task table. After the fork (for the spawn call), the new child adds itself to the task table and then waits for the "user" to finish before executing. So, the user finishes what it needs, calls the end method on "main", which checks to see if there's a waiting process. It turns out when I show() my task table, the new child that I added isn't there! I can't figure out why at all. Any ideas?

Here's the 2nd child when it gets created.

Code:
pid = Fork(); 
if(pid == 0) { 
      //blah blah 
      tbl -> set(spawn_tid_c, spawn_pid_c); 
      tbl -> show(); 
      //wait 
}

Here's the output.

+ main + forking
+ TaskTbl + set(01, 19976) method called
+ TaskTbl + (01, 19976) added
<TaskTbl> has 2 items
0: <00,19975>
1: <01,19976>
+ main + waiting for system call message
+ user1 + calling s_end()
+ main + syscall task end received
<TaskTbl> has 1 items
0: <00,19975>

the end function is called immediately after the spawn function finishes, and I've checked everywhere to find something that would remove the task but the only way to do so would be for me to intentionally remove it ( remove -> (task, proc)), which I'm not doing.

I have no idea why the table is only showing 1 item immediately after. Help would be greatly appreciated.
 
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