- Nov 25, 2017
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I write my own programs for academic projects, mostly involving numerical analysis.
I have one that I'd like to run over several CPUs simultaneously to get through a few runs.
I've set up a script that runs the program (say 30 times). I duplicate the script (say 8 times, one per CPU) and then run it. Each script runs in a different directory.
If I set off the scripts with a little delay between each one then as long as the program is still running by the time I set off the last one, all works well.
The problem I have is that when multiple versions of the program start simultaneously, Windows seems to slow down to a crawl on starting programs. Once the program gets going though it runs at normal speed. The computer remains slow to start other things to requiring a reboot. The shorter time that my code runs, the worse this is because more instances of the code start at the same time.
To rule out my code causing a memory leak, I reduced it to a "Hello World" type code and this slowdown still happens.
I ruled out the compiler causing a problem by using gfortran (64 bit) and Lazarus (64 bit). The effect is the same.
I wondered if using the same name for each instance of code running was the problem but running a different named version of the executable in each script doesn't help.
The problem arises on two separate computers, one running Windows 7 Home, the other Windows 10 Educational.
Taskmanager shows that CPU and memory usage are low when the computer is slow.
Can anyone help?
(I've posted a similar message on Windows 10 so I hope this is OK - I've googled aplenty but keep finding general "why does windows slow down" messages. This is specific.)
I have one that I'd like to run over several CPUs simultaneously to get through a few runs.
I've set up a script that runs the program (say 30 times). I duplicate the script (say 8 times, one per CPU) and then run it. Each script runs in a different directory.
If I set off the scripts with a little delay between each one then as long as the program is still running by the time I set off the last one, all works well.
The problem I have is that when multiple versions of the program start simultaneously, Windows seems to slow down to a crawl on starting programs. Once the program gets going though it runs at normal speed. The computer remains slow to start other things to requiring a reboot. The shorter time that my code runs, the worse this is because more instances of the code start at the same time.
To rule out my code causing a memory leak, I reduced it to a "Hello World" type code and this slowdown still happens.
I ruled out the compiler causing a problem by using gfortran (64 bit) and Lazarus (64 bit). The effect is the same.
I wondered if using the same name for each instance of code running was the problem but running a different named version of the executable in each script doesn't help.
The problem arises on two separate computers, one running Windows 7 Home, the other Windows 10 Educational.
Taskmanager shows that CPU and memory usage are low when the computer is slow.
Can anyone help?
(I've posted a similar message on Windows 10 so I hope this is OK - I've googled aplenty but keep finding general "why does windows slow down" messages. This is specific.)
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