How to clean up R memory without the need to restart my PC

Question

I am running my code in R  under Windows  which involves a lot of in-memory data  I tried to use rm list ls    to clean up memory  but seems the memory is still occupied and I cannot rerun my code  I tried to close the R and restart R again  but it is the same  seems memory is still occupied as when I run the codes it says it can t allocate memory  but it could at the first time   The memory seems only cleaned up after I restart my PC   Is there any way to clean up the memory so that I can rerun my code without restarting my PC every time

User · Answer

I came under the same problem with R  I dig a bit and come with a solution  that we need to restart R session to fully clean the memory RAM  For this  you can use a simple code after removing everything from your workspace  the code is as follows    rm list   ls      rs restartR

User · Answer

Use ls   function to see what R objects are occupying space  use rm  objectName   to clear the objects from R memory that is no longer required  See this too

User · Answer

I ve found it helpful to go into my  tmp  folder and delete all hanging rsession files  This usually frees any memory that seems to be  stuck

User · Answer

memory size max T    gives the amount of memory obtained by the OS  1  1800 memory size max F    gives the amount of memory being used  1  261 17   Using Paul s example   m   matrix runif 10e7   10000  1000    Now  memory size max F   1  1024 18   To clear up the memory  gc   memory size max F   1  184 86   In other words  the memory should now be clear again  If you loop a code  it is a good idea to add a gc   as the last line of your loop  so that the memory is cleared up before starting the next iteration

User · Answer

Maybe you can try to use the function gc    A call of gc   causes a garbage collection to take place  It can be useful to call gc   after a large object has been removed  as this may prompt R to return memory to the operating system  gc   also return a summary of the occupy memory

User · Answer

Just adding this for reference in case anybody needs to restart and immediatly run a command   I m using this approach just to clear RAM from the system  Make sure you have deleted all objects no longer required  Maybe gc   can also help before hand  But nothing will clear RAM better as restarting the R session   library rstudioapi  restartSession command    print  x

User · Answer

An example under Linux  Fedora 16  shows that memory is freed when R is closed     free -m                                                                                                                                                                                                                                                  total       used       free     shared    buffers     cached                                                                                                                                                                     Mem           3829       2854        974          0        344       1440                                                                                                                                                                     -   buffers cache        1069       2759                                                                                                                                                                                                      Swap          4095         85       4010        2854 megabytes is used  Next I open an R session and create a large matrix of random numbers   m   matrix runif 10e7   10000  1000    when the matrix is created  3714 MB is used     free -m                                                                                                                                                                                                                                                  total       used       free     shared    buffers     cached                                                                                                                                                                     Mem           3829       3714        115          0        344       1442                                                                                                                                                                     -   buffers cache        1927       1902                                                                                                                                                                                                      Swap          4095         85       4010        After closing the R session  I nicely get back the memory I used  2856 MB free      free -m                                                                                                                                                                                                                                                  total       used       free     shared    buffers     cached                                                                                                                                                                     Mem           3829       2856        972          0        344       1442                                                                                                                                                                     -   buffers cache        1069       2759                                                                                                                                                                                                      Swap          4095         85       4010      Ofcourse you use Windows  but you could repeat this excercise in Windows and report how the available memory develops before and after you create this large dataset in R

User · Answer

There is only so much you can do with rm   and gc    As suggested by Gavin Simpson  even if you free the actual memory in R  Windows often won t reclaim it until you close R or it is needed because all the apparent Windows memory fills up   This usually isn t a problem  However  if you are running large loops this can sometimes lead to fragmented memory in the long term  such that even if you free the memory and restart R - the fragmented memory may prevent you allocating large chunks of memory  Especially if other applications were allocated fragmented memory while you were running R  rm   and gc   may delay the inevitable  but more RAM is better

[r] How to clean up R memory (without the need to restart my PC)?

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