Just for the record, i just started programing on python, and this is the first time i try to do a daemon.
I have a problem handling DB connections in a daemon i've been working on, the first thing i do, is connect to my postgres db with:
try:
psycopg2.apilevel = '2.0'
psycopg2.threadsafety = 3
cnx = psycopg2.connect( "host='192.168.10.36' dbname='db' user='vas' password='vas'")
except Exception, e:
print "Unable to connect to DB. Error [%s]" % ( e,)
exit( )
after that I select all rows in the DB that are with status = 0:
try:
cursor = cnx.cursor( cursor_factory = psycopg2.extras.DictCursor)
cursor.execute( "SELECT * FROM table WHERE status = 0")
rows = cursor.fetchall( )
cursor.close( )
except Exception, e:
print "Error on sql query [%s]" % ( e,)
then if there are rows selected the program forks into:
while 1:
try:
psycopg2.apilevel = '2.0'
psycopg2.threadsafety = 3
cnx = psycopg2.connect( "host='192.168.10.36' dbname='sms' user='vas' password='vas'")
except Exception, e:
print "Unable to connect to DB. Error [%s]" % ( e,)
exit( )
if rows:
daemonize( )
for i in rows:
try:
global q, l
q = Queue.Queue( max_threads)
for i in rows:
cursor = cnx.cursor( cursor_factory = psycopg2.extras.DictCursor)
t = threading.Thread( target=sender, args=(i, cursor))
t.setDaemon( True)
t.start( )
for i in rows:
q.put( i)
q.join( )
except Exception, e:
print "Se ha producido el siguente error [%s]" % ( e,)
exit( )
else:
print "No rows where selected\n"
time.sleep( 5)
My daemonize function looks like this:
def daemonize( ):
try:
pid = os.fork()
if pid > 0:
sys.exit(0)
except OSError, e:
print >>sys.stderr, "fork #1 failed: %d (%s)" % (e.errno, e.strerror)
sys.exit(1)
os.chdir("/")
os.umask(0)
try:
pid = os.fork()
if pid > 0:
sys.exit(0)
except OSError, e:
print >>sys.stderr, "fork #2 failed: %d (%s)" % (e.errno, e.strerror)
sys.exit(1)
threads target to sender function:
def sender( row, db):
while 1:
item = q.get( )
if send_to( row['to'], row['text']):
db.execute( "UPDATE table SET status = 1 WHERE id = %d" % sms['id'])
else:
print "UPDATE table SET status = 2 WHERE id = %d" % sms['id']
db.execute( "UPDATE table SET status = 2 WHERE id = %d" % sms['id'])
db.close( )
q.task_done( )
send_to
function just opens a url and return true or false on success
Since yesterday i keep getting these error and cant find my way thru:
UPDATE outbox SET status = 2 WHERE id = 36
Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.6/threading.py", line 525, in __bootstrap_inner
self.run()
File "/usr/lib/python2.6/threading.py", line 477, in run
self.__target(*self.__args, **self.__kwargs)
File "sender.py", line 30, in sender
db.execute( "UPDATE table SET status = 2 WHERE id = %d" % sms['id'])
File "/usr/lib/python2.6/dist-packages/psycopg2/extras.py", line 88, in execute
return _cursor.execute(self, query, vars, async)
OperationalError: server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.