parallel processing - Is there a limit on the number of slaves that R snow can create? -


i'm trying build snow cluster around 120 processes on 3 different hosts. these amd servers 48 cores each. after building approx first 90 slaves error:

cl = makesockcluster(c(rep("localhost", 44), rep("host2", 46), rep("host3", 45))) error in socketconnection(port = port, server = true, blocking = true,  :    connections in use > traceback() 3: socketconnection(port = port, server = true, blocking = true,         open = "a+b") 2: newsocknode(names[[i]], options = options, rank = i) 1: makesockcluster(c(rep("localhost", 44), rep("host2", 46),         rep("host3", 45)))

i checked system limits , don't see problem:

# cat /proc/sys/fs/file-max 12897622 # grep "#define __fd_setsize" /usr/include/*.h /usr/include/*/*.h /usr/include/linux/posix_types.h:#define __fd_setsize   1024 # ulimit -a |grep open open files                      (-n) 65536

is there limit on number of processes snow can create?

yes, because there limit on total number of connections r can create (currently 128). includes more socket connections, that's why can ~90 worker nodes.

> grep "define nconnections" * connections.c:#define nconnections 128 /* snow needs 1 per slave node */

since you're using gnu/linux, suggest using multicore instead of snow.


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