Computationally intensive programs 'stall out'












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I've been having some issues running code on my Ubuntu systems. The same error occurs on my 14.04 workstation, and my 16.04 laptop. I write code to diagonalize matrices or do tensor manipulations, and the task isn't one big, gigantic problem, but one relatively manageable problem repeated several hundred or thousand times, with certain parameters tweaked. For example, I could be running code to find eigenvalues of a matrix, and then the same matrix but with a few numbers changed, and again and again. This problem occurs with code I write in Julia and C++, though I expect similar things will happen if I use Python.



When I run the code, at first the program seems to run smoothly, but after a few dozen iterations it stops producing output. Running top shows that the CPU is still being used for the process, but no more output is being produced, even though the same problem (with slightly different parameters) had run perfectly well for several dozen iterations before. The RAM usage is low (~5%), and Ubuntu doesn't freeze or slow down at all. There's nothing special about the exact moment when it stops working - I can rerun the code with the same parameters when the program stopped, and it works fine, until a few dozen more iterations pass and the problem occurs again.



One special thing I noticed when running top was that the program stalling out was almost always associated with a decrease in processor usage. When the program runs fine, it uses 400-600% of my CPU, but when it stalls out that number always drops to 100%.



I'd be grateful for any ideas at all. Thanks in advance.










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    I've been having some issues running code on my Ubuntu systems. The same error occurs on my 14.04 workstation, and my 16.04 laptop. I write code to diagonalize matrices or do tensor manipulations, and the task isn't one big, gigantic problem, but one relatively manageable problem repeated several hundred or thousand times, with certain parameters tweaked. For example, I could be running code to find eigenvalues of a matrix, and then the same matrix but with a few numbers changed, and again and again. This problem occurs with code I write in Julia and C++, though I expect similar things will happen if I use Python.



    When I run the code, at first the program seems to run smoothly, but after a few dozen iterations it stops producing output. Running top shows that the CPU is still being used for the process, but no more output is being produced, even though the same problem (with slightly different parameters) had run perfectly well for several dozen iterations before. The RAM usage is low (~5%), and Ubuntu doesn't freeze or slow down at all. There's nothing special about the exact moment when it stops working - I can rerun the code with the same parameters when the program stopped, and it works fine, until a few dozen more iterations pass and the problem occurs again.



    One special thing I noticed when running top was that the program stalling out was almost always associated with a decrease in processor usage. When the program runs fine, it uses 400-600% of my CPU, but when it stalls out that number always drops to 100%.



    I'd be grateful for any ideas at all. Thanks in advance.










    share|improve this question







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      I've been having some issues running code on my Ubuntu systems. The same error occurs on my 14.04 workstation, and my 16.04 laptop. I write code to diagonalize matrices or do tensor manipulations, and the task isn't one big, gigantic problem, but one relatively manageable problem repeated several hundred or thousand times, with certain parameters tweaked. For example, I could be running code to find eigenvalues of a matrix, and then the same matrix but with a few numbers changed, and again and again. This problem occurs with code I write in Julia and C++, though I expect similar things will happen if I use Python.



      When I run the code, at first the program seems to run smoothly, but after a few dozen iterations it stops producing output. Running top shows that the CPU is still being used for the process, but no more output is being produced, even though the same problem (with slightly different parameters) had run perfectly well for several dozen iterations before. The RAM usage is low (~5%), and Ubuntu doesn't freeze or slow down at all. There's nothing special about the exact moment when it stops working - I can rerun the code with the same parameters when the program stopped, and it works fine, until a few dozen more iterations pass and the problem occurs again.



      One special thing I noticed when running top was that the program stalling out was almost always associated with a decrease in processor usage. When the program runs fine, it uses 400-600% of my CPU, but when it stalls out that number always drops to 100%.



      I'd be grateful for any ideas at all. Thanks in advance.










      share|improve this question







      New contributor




      AureySteader is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.












      I've been having some issues running code on my Ubuntu systems. The same error occurs on my 14.04 workstation, and my 16.04 laptop. I write code to diagonalize matrices or do tensor manipulations, and the task isn't one big, gigantic problem, but one relatively manageable problem repeated several hundred or thousand times, with certain parameters tweaked. For example, I could be running code to find eigenvalues of a matrix, and then the same matrix but with a few numbers changed, and again and again. This problem occurs with code I write in Julia and C++, though I expect similar things will happen if I use Python.



      When I run the code, at first the program seems to run smoothly, but after a few dozen iterations it stops producing output. Running top shows that the CPU is still being used for the process, but no more output is being produced, even though the same problem (with slightly different parameters) had run perfectly well for several dozen iterations before. The RAM usage is low (~5%), and Ubuntu doesn't freeze or slow down at all. There's nothing special about the exact moment when it stops working - I can rerun the code with the same parameters when the program stopped, and it works fine, until a few dozen more iterations pass and the problem occurs again.



      One special thing I noticed when running top was that the program stalling out was almost always associated with a decrease in processor usage. When the program runs fine, it uses 400-600% of my CPU, but when it stalls out that number always drops to 100%.



      I'd be grateful for any ideas at all. Thanks in advance.







      scripts c++ julia-lang






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