[Zope-dev] Re: zdaemon fix

[Guido van Rossum]

BTW, here's the patch I propose:

*** Daemon.py	14 Aug 2002 22:12:52 -0000	1.11
--- Daemon.py	5 Oct 2002 08:14:51 -0000
***************
*** 17,22 ****
--- 17,28 ----
  import zLOG
  from SignalPasser import SignalPasser
  
+ # If zdaemon finds that it is continuously respawning more than 10
+ # times in 2 minutes, it will assume that there is an error, log a
+ # PANIC level message, and exit.
+ RESPAWN_TIME = 120 # 2 minutes
+ RESPAWN_LIMIT = 10 # 10 times
+ 
  pyth = sys.executable
  
  class DieNow(Exception):
***************
*** 32,38 ****
--- 38,54 ----
      if not os.environ.has_key('Z_DEBUG_MODE'):
          detach() # detach from the controlling terminal
  
+     starttimes = [] # for RESPAWN_LIMIT
      while 1:
+         # Give up if respawning too often
+         starttimes.append(time.time())
+         if len(starttimes) > RESPAWN_LIMIT:
+             del starttimes[0]
+             if starttimes[-1] - starttimes[0] < RESPAWN_TIME:
+                 pstamp('Respawning more than %d times in %d seconds. Quit.' %
+                        (RESPAWN_LIMIT, RESPAWN_TIME), zLOG.PANIC)
+                 sys.exit(1)
+             del starttimes[0]
          try:
              pid = os.fork()
              if pid:


While we're improving zdaemon, I have two other suggestions:

- Use grown-up language in log messages rather than "Aiieee!" and
  "Houston, we have forked"

- Why does zdaemon add "zdaemon: <timestamp>: " to its log messages?
  That info is already added by zLOG.

A typical set of zdaemon log messages now looks like this:

------
2002-10-05T04:23:31 INFO(0) zdaemon zdaemon: Sat Oct  5 04:23:31 2002: Houston,
                    we have forked: pid 2915
------
2002-10-05T04:24:12 ERROR(200) zdaemon zdaemon: Sat Oct  5 04:24:12 2002:
                    Aiieee! Process 2915 terminated normally, exit status: 1
------

while it could look like this:

------
2002-10-05T04:23:31 INFO(0) zdaemon Started subprocess: pid 2915
------
2002-10-05T04:24:12 ERROR(200) zdaemon Process 2915 terminated normally, exit
                    status: 1
------

--Guido van Rossum (home page: http://www.python.org/~guido/)