R help - Jul 2020 - parallel number of cores according to memory?

if I understand correctly, R makes a copy of the full environment for each
process.  thus, even if I have 32 processors, if I only have 64GB of RAM
and my R process holds about 10GB, I should probably not spawn 32 processes.

has anyone written a function that sets the number of cores for use (in
mclapply) to be guessed at by appropriate memory requirements (e.g.,
"amount-of-RAM"/"RAM held by R")?

(it would be even nicer if I could declare my 8GB data frame to be
read-only and to be shared among my processes, but this is presumably
technically very difficult.)

pointers appreciated.

/iaw

	[[alternative HTML version deleted]]

Use an operating system that supports forking, like Linux or MacOSX, and use the
parallel package mclapply function or similar to share memory for read
operations. [1]

And stop posting in HTML here.

[1] https://cran.r-project.org/web/views/HighPerformanceComputing.html

On July 7, 2020 9:20:39 PM PDT, ivo welch <ivowel at gmail.com>
wrote:
>if I understand correctly, R makes a copy of the full environment for
>each
>process.  thus, even if I have 32 processors, if I only have 64GB of
>RAM
>and my R process holds about 10GB, I should probably not spawn 32
>processes.
>
>has anyone written a function that sets the number of cores for use (in
>mclapply) to be guessed at by appropriate memory requirements (e.g.,
>"amount-of-RAM"/"RAM held by R")?
>
>(it would be even nicer if I could declare my 8GB data frame to be
>read-only and to be shared among my processes, but this is presumably
>technically very difficult.)
>
>pointers appreciated.
>
>/iaw
>
>	[[alternative HTML version deleted]]
>
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-- 
Sent from my phone. Please excuse my brevity.

ugghhh---apologies.  although in 2020, it would be nice if the mailing
list had an automatic html filter (or even bouncer!)

I am using macos.  alas, my experiments suggest that `mclapply()` on a
32-core intel system with 64GB of RAM, where the input data frame is
8GB and the output is about 500MB per core (to be stitched together
into about 16GB), the system starts swapping like crazy, comes to a
halt, and then usually crashes.

/iaw