subprocess.Popen still waits when starting Rserve

Question

Local system: OSX 10.10.3 Yosemite Python 2.7

Remote Server: NAME="Amazon Linux AMI" VERSION="2014.09"

I'm trying to use Python to start (restart) the Rserve processes on the server. I'm able to start it as ec2-user either directly ($R CMD Rserve --vanilla) or using a SystemV script ($service Rserve restart)...however the Python script still hangs waiting for the started Rserve process to finish. Since it's a daemon, it doesn't finish and the script hangs.

I have tried both subprocess.call AND subprocess Popen.

log.error('Attempting to restart Rserve environment...')
PEM  = "/Users/xxx/ra.pem"
USER = "ec2-user"
PORT = '22'
SERVER = str(callobj.rhandler_host) # ends up confirmed correct IP
command = ['/sbin/service', 'Rserve', 'restart'] # Starts Rserve and hangs
# command = ['R', 'CMD', 'Rserve', '--vanilla'] # Starts Rserve and hangs
# command = ['ls'] # lists and finishes

ssh = ['ssh', '-i', PEM, '-p', PORT, USER + '@' + SERVER]
run = ssh + command

proc = subprocess.Popen(run, shell=False, 
#                         stdout=subprocess.PIPE) # Tried this, no change 
                          stdin=None, stdout=None, stderr=None, close_fds=True)

OUTPUT:

2015-06-06 16:51:51,362 - MRATrefactor - ERROR - [R] environment does not appear to be running on server '54.xxx.xxx.x2'. Connection denied, server not reachable or not accepting connections
2015-06-06 16:51:51,363 - MRATrefactor - ERROR - rserveHandler.connect: ; *args: None; **kwargs: None; RserveNotRunning: [R] environment does not appear to be running on server '54.xxx.xxx.x2'. Connection denied, server not reachable or not accepting connections. Rserve may not be running.
2015-06-06 16:51:51,363 - MRATrefactor - ERROR - Attempting to restart Rserve environment...
    PID: 8205
    Cannot match 8205 to running processes.
    Grepping for process [expecting PID: 8205]...

    grep count: 0
    0
    Stopping Rserve:  [FAILED]
    Starting Rserve: 
    R version 3.1.1 (2014-07-10) -- "Sock it to Me"
    Copyright (C) 2014 The R Foundation for Statistical Computing
    Platform: x86_64-redhat-linux-gnu (64-bit)

    R is free software and comes with ABSOLUTELY NO WARRANTY.
    You are welcome to redistribute it under certain conditions.
    Type 'license()' or 'licence()' for distribution details.

    Natural language support but running in an English locale

    R is a collaborative project with many contributors.
    Type 'contributors()' for more information and 'citation()' on how to cite R or R packages in publications.

    Type 'demo()' for some demos, 'help()' for on-line help, or 'help.start()' for an HTML browser interface to help.
    Type 'q()' to quit R.

    Rserv started in daemon mode.
    ec2-user 8385 1 0 14:51 ? 00:00:00 /usr/lib64/R/bin/Rserve --vanilla
    PID: 8385
    Starting Rserve:  [  OK  ]

(and script hangs here...apparently (maybe) waiting...?)