Hello,
I spent a lot of a time on a weird bug, and I just managed to narrow it down.
In parallel code (here with parallel::mclappy, but I got it
doMC/multicore too), if the library(tcltk) is loaded, R hangs when
trying to open a DB connection.
I got the same behaviour on two different computers, one dual-core,
and one 2 xeon quad-core.
Here's the code:
library(parallel)
library(RSQLite)
library(tcltk)
#unloadNamespace("tcltk")
res <- mclapply(1:2, function(x) {
db <- DBI::dbConnect("SQLite", ":memory:")
}, mc.cores=2)
print("Done")
When I execute it (R --vanilla < test_parallel_db.R), it hangs
forever, and I have to type several times CTRL+C to interrupt it. I
then get this message:
Warning messages:
1: In selectChildren(ac, 1) : error 'Interrupted system call' in select
2: In selectChildren(ac, 1) : error 'Interrupted system call' in select
Then, just remove library(tcltk), or uncomment
unloadNamespace("tcltk"), and it works fine again.
I guess there's a bug somewhere, but where exactly ?
Best,
Karl Forner
Further info:
R version 2.15.1 (2012-06-22) -- "Roasted Marshmallows"
Copyright (C) 2012 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
Platform: x86_64-unknown-linux-gnu (64-bit)
ubuntu 12.04 and 12.10
ubuntu package tk8.5
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