matthewstory · January 20, 2022 15:05 · Mar 31, 2014 · Jan 16, 2013
diff --git a/gistfile1.py b/gistfile1.py
@@ -1,6 +1,7 @@
 import os
 import signal
 import sys 
+import select
 import errno
 
 from jsonrpclib.SimpleJSONRPCServer import SimpleJSONRPCServer
@@ -29,7 +30,7 @@ def _gogentle(signum, frame):
     '''Do not throw a KeyboardInterrupt Error'''
     os._exit(1)
 
-# API 
+# API
 def add(x, y): 
     '''Add x and y'''
     return x + y 
@@ -55,7 +56,7 @@ def main(name, *argv):
         # fork our current process
         pid = os.fork()
 
-        # if we are the child fork ... 
+        # if we are the child fork ...
         if 0 == pid:
             # die without unhandled exception
             for signum in ( signal.SIGINT, signal.SIGTERM, ):
@@ -75,8 +76,22 @@ def main(name, *argv):
 
     # wait on the kids
     while len(_PIDS):
-        pid, rc = os.waitpid(-1, 0)
-        _PIDS.remove(pid)
+        # 1s timeout here means we're checking for exiting children at most
+        # 1x per second, prevents a busy loop
+        reads, _, _ = select.select([sys.stdin], [], [], 1)
+        if sys.stdin in reads:
+            # blocking, read 1 line
+            cmd = sys.stdin.readline()
+            # kill ourselves ... kronos will propegate
+            if cmd.strip() == 'exit':
+                os.kill(os.getpid(), signal.SIGTERM)
+
+        # check for exited children, non-blocking
+        while True:
+            pid, rc = os.waitpid(-1, os.WNOHANG)
+            if not pid:
+                break
+            _PIDS.remove(pid)
 
     return 0
 

diff --git a/gistfile1.py b/gistfile1.py
@@ -0,0 +1,84 @@
+import os
+import signal
+import sys 
+import errno
+
+from jsonrpclib.SimpleJSONRPCServer import SimpleJSONRPCServer
+
+# BOOK-KEEPING
+_PIDS = []
+
+def _kronos(signum, frame):
+    '''As Kronos did before us, we too may have to devour our children'''
+    for pid in _PIDS:
+        try:
+            os.kill(pid, signum)
+        except OSError, e:
+            if e.errno == errno.ESRCH:
+                _PIDS.remove(pid)
+
+    # wait on all child processes
+    while len(_PIDS):
+        pid, rc = os.waitpid(-1, 0)
+        _PIDS.remove(pid)
+
+    # exit non-zero to signal abnormal termination
+    sys.exit(1)
+
+def _gogentle(signum, frame):
+    '''Do not throw a KeyboardInterrupt Error'''
+    os._exit(1)
+
+# API 
+def add(x, y): 
+    '''Add x and y'''
+    return x + y 
+
+def subtract(x, y): 
+    '''Subtract y from x'''
+    return x - y 
+
+# server
+def main(name, *argv):
+    global _PIDS
+
+    # JSON-RPC over HTTP on INET socket localhost:8888
+    # under the hood, this calls `socket.bind` then `socket.listen`
+    s = SimpleJSONRPCServer(( argv[0], int(argv[1]), ))
+
+    # register our logging math functions
+    for fn in ( add, subtract, ):
+        s.register_function(fn)
+
+    # simple pre-fork server, fork before accept
+    for i in range(int(argv[2])):
+        # fork our current process
+        pid = os.fork()
+
+        # if we are the child fork ... 
+        if 0 == pid:
+            # die without unhandled exception
+            for signum in ( signal.SIGINT, signal.SIGTERM, ):
+                signal.signal(signum, _gogentle)
+
+            # under the hood, this calls `socket.accept`
+            s.serve_forever()
+            os._exit(0)
+
+        # if we are the papa fork
+        else:
+            _PIDS.append(pid)
+
+    # setup signal relaying for INT and TERM
+    for signum in ( signal.SIGINT, signal.SIGTERM, ):
+        signal.signal(signum, _kronos)
+
+    # wait on the kids
+    while len(_PIDS):
+        pid, rc = os.waitpid(-1, 0)
+        _PIDS.remove(pid)
+
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main(*sys.argv))