On 2 August 2019 at 16:23, Sun Yijiang wrote:
| The R script I run daily for hours looks like this:
|
| while (!finish) {
| Sys.sleep(0.1)
| time = as.integer(format(Sys.time(), "%H%M")) # always crash here
| if (new.data.timestamp() <= time)
| next
| # ... do some jobs for about 2 minutes ...
| gc()
| }
|
| Basically it waits for new data, which comes in every 10 minutes, and
| do some jobs, then gc(), then loop again. It works great most of the
| time, but crashes strangely once a month or so. Although infrequent,
| it always crashes at the same place and gives the same error info,
| like this:
A really long time ago in a galaxy not too far away I also shephearded such
jobs where the job were left running for a long time from a single "outer"
call, and aimed to control resources via gc(), Sys.sleep()and alike.
Doing that, I learned a different session. As R is an fact _an environment_
taking care of a great many things, robustness can be had more easily via
fresh processes. Since then I mostly control the jobs _from the outside_ via
cron, and aim to have well-defined taks (with few dependencies, a different
topic). I do the same for e.g. package testing and loading/unloading of
shared libraries: hard to get right, easier to test in vanilla sessions.
These are also some of the reasons I joined Jeff Horner in his then-nascient
littler project, and continue to look after it. I run many (automated) jobs
with it from cron, and this generally works _great_. Rscript came just a
little bit later, has also improved over time and is a fine alternative.
Lastly, I would recommend to take advantage of the fact that POSIXct is in
fact numeric internally and rewrite this as
currentTime <- as.numeric(Sys.time())
if (currentTime > prevTime + minDelta) {
# do stuff ...
prevTime <- currentTime
}
That alone may help you as you no longer need all the temporary string
objects you were chasing through the debugger.
Good luck, and keep re-engineering your scripts. R can be a very, very
reliable tool when driven the right way.
Cheers, Dirk
--
http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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