Best Way to Start a Second Program?

[Adak]

Inside my program, I need to call a second program ("solver.exe") and then the first program can pick back up, right where it left off. This is done about once each minute.

Right now I'm using:

//my program's other code up here:
for(i = 0; i < BigNumber; i++)  {
   //miscellaneous other code of mine
   system("solver.exe < inputFile");
   //more code of mine
}

This works, but I see a lot of other options for this, in C.

Would another way be faster, and still reliable?

This is part of my Sudoku analysis program, and the run time is *absolutely HUGE* - (many years, on the fastest hardware, running multiple work units which break the job into smaller pieces)

Thanks.

[Dino]

I'm not up so much on Windows architecture, but I suspect calling system() has a lot of overhead, starting up a new process, loading the executable (don't know if it's cached or not), and so on.

Is there a way to load the exe into storage and keep it there, and then just call it without all the overhead of starting a new process over and over?

[MK27]

Is there a way to load the exe into storage and keep it there, and the just call it without all the overhead of starting a new process over and over?

Or just leave it sleeping and add a little IPC to both programs. Actually I think that is what you meant.

[Adak]

Yes, Dino, the executable is cached.

MK, what is ISP?

[MK27]

MK, what is ISP?

It's dyslexic for "Inter Process Communication", silly. Like (for example) you thread a socket server into one program and a client into the other so they can send instructions back and forth. So solver.exe is started only once, then sleeps waiting for a call. This way, you don't have to keep reloading it. On linux this would be parallel to a "daemon service".

[brewbuck]

This is something that happens about one a minute and we're talking about how to speed it up by a few hundred microseconds?

[Adak]

This is something that happens about one a minute and we're talking about how to speed it up by a few hundred microseconds?

I brought this up because I was having trouble with the program crashing after about 30 such calls.

My first thought was "it must be something to do with using system()" over and over. That's what prompted this thread.

After sleeping on it, I thought "funny, it crashes just about how DOS used to crash when it ran out of file handles..."

Which led me to the startling discovery that *somehow*, AFTER the data file was closed, and the system("otherprogram") had run, my program was *again* writing data to the file, and that data was good!! <ay carumba!> I had never seen that kind of run time behavior. It was just losing one file handle in the process. After adding the file open block of code, after the call to system(), it is all running fine.

Right now, I have no idea how to code up MK's suggestion, but it sounds more elegant than calling system(), repeatedly. My "big idea" is to integrate these two programs, but anything that can help in the mean time, is very welcome.

I'll be back for more substantial algorithmic advice, soon.