problem implementing fork

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Old 10-12-2009
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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pthread_atfork(3T)														pthread_atfork(3T)

pthread_atfork() - register fork handlers. SYNOPSIS
prepare This function is called before performing the parent This function is called in the parent process after performing the child This function is called in the child process after performing the DESCRIPTION
The function allows an application to install fork handlers. These fork handlers will be called before and after a operation. These han- dlers will be called in the context of the thread calling Similar to the handlers, the application does not need to do anything special for these fork handlers to be called. They will be invoked by the system when a operation occurs. The function is called before the operation in the parent process. The function is called after the operation in the parent process. The function is called after the operation in the child process. If a fork handler is not needed in one or more of these three places, the appropriate fork handler parameter may be set to NULL. A process may install multiple fork handling functions. The and fork handlers will be called in the order in which they were installed (i.e., The fork handlers will be called in the opposite order (i.e., RETURN VALUE
Upon successful completion, returns zero. Otherwise, an error number is returned to indicate the error (the variable is not set). ERRORS
If any of the following occur, the function returns the corresponding error number: [ENOMEM] There is insufficient table space to install the fork handlers. AUTHOR
was derived from the IEEE POSIX P1003.1c standard. SEE ALSO
fork(2), atexit(3). STANDARDS CONFORMANCE
Pthread Library pthread_atfork(3T)

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