[R] Way to make R idle for some time and try something again later

[Duncan Murdoch]

Don MacQueen wrote:
> I done something very similar -- have R watch a file, and whenever 
> new data is added to the file, read the new data from the file. In my 
> case, new data was arriving once per minute, so I needed to have R 
> wait about a minute before looking for new data.
> 
> On my unix-based system, I found that if I usd
>        Sys.sleep( N )
> then cpu usage immediately went up drastically. If the the system is 
> otherwise fairly idle, cpu usage goes up to nearly 100%. A cpu 
> monitor shows that R is using the cpu cycles.

This is system-specific.  In Windows, CPU usage measures in at 0% while 
in a Sys.sleep loop.  (It's not really zero, because R checks for events 
to update the display, but it's very low).

Duncan Murdoch

> 
> If I use instead
>       system('sleep N')
> cpu usage does not go up.
> 
> (where N is the number of seconds to sleep)
> 
> 
>> version
> 
>           _                       
> platform powerpc-apple-darwin7.9.0
> arch     powerpc                 
> os       darwin7.9.0             
> system   powerpc, darwin7.9.0    
> status                           
> major    2                       
> minor    1.1                     
> year     2005                    
> month    06                      
> day      20                      
> language R                       
> 
> 
> At 12:13 PM -0700 7/29/05, Tae-Hoon Chung wrote:
> 
>>Hi, All;
>>
>>I have a question. In R, what is the best way to make R idle for a while and
>>try something again later? For example, suppose there is an R job which
>>accesses a file that may be shared with other active jobs. So when the file
>>is being accessed by other job, your job will not be able to access the file
>>and your job will crash because of that. To avoid this, you want your job to
>>try to access the file repeatedly with some time interval, say every 10
>>seconds or something like that. Which is the best way to do this in R?
>>
>>Thanks in advance,
>>
>>Tae-Hoon Chung
>>
>>Post-Doctoral Researcher
>>Translational Genomics Research Institute (TGen)
>>445 N. 5th Street (Suite 530)
>>Phoenix, AZ 85004
>>1-602-343-8724 (Direct)
>>1-480-323-9820 (Mobile)
>>1-602-343-8840 (Fax)
>>
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> 
> 
>