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problem implementing fork


 
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# 8  
Old 10-11-2009
A couple of things come to mnd....
  1. I'd use something other than SIGALRM to signal the parent. Perhaps SIGCHLD or SIGUSR1
  2. Forking gives the parent the opportunity to do something useful if the kid hangs. For instance, if the I/O subsystem were to be unable to complete an i/o and fail to return an error on a Solaris (or any system using DMA for I/O) , the kid will be unkillable and hang. This is because you might remove the process memory, reallocate it to another process only to have the DMA device complete the physical i/o. It might be useful to tell someone about the i/o issue via a timeout mechanism.
  3. Is forking all that expensive in a Linux system? Most everything except for the LWP stuff will be created with either model. The forking model makes expansion of the code to handle multiple tasks saner..

sorry about the late reply...

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FORK(3F)																  FORK(3F)

NAME
fork - create a copy of this process SYNOPSIS
integer function fork() DESCRIPTION
Fork creates a copy of the calling process. The only distinction between the 2 processes is that the value returned to one of them (referred to as the `parent' process) will be the process id of the copy. The copy is usually referred to as the `child' process. The value returned to the `child' process will be zero. All logical units open for writing are flushed before the fork to avoid duplication of the contents of I/O buffers in the external file(s). If the returned value is negative, it indicates an error and will be the negation of the system error code. See perror(3F). A corresponding exec routine has not been provided because there is no satisfactory way to retain open logical units across the exec. How- ever, the usual function of fork/exec can be performed using system(3F). FILES
/usr/lib/libU77.a SEE ALSO
fork(2), wait(3F), kill(3F), system(3F), perror(3F) 4.2 Berkeley Distribution May 27, 1986 FORK(3F)

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