Restarting a program after exception
Refactor this - you'll get a stackoverflow error sooner or later if you have enough failures.
queryRepeatedly
should just be query
. It should return void
and throw exceptions on failures.
Wrap in something that looks like this, your true queryRepeatedly
function?
while True:
try:
query()
except:
#handle
time.sleep(15)
All looping, no recursion needed.
Note that you must think carefully about how much of your program you need to restart. From your question it sounded like your actual problem was ensuring the query could try again if it sporadically fails, which is what my solution ensures. But if you want to clean up program resources - say, bounce SQL connections, which may have broken - then you need to think more carefully about how much of your program you need to "restart." In general you need to understand why your query failed to know what to fix, and in the extreme case, the right thing to do is an email or SMS to someone on call who can inspect the situation and write an appropriate patch or fix.
To restart anything, just use a while
loop outside the try
. For example:
def foo():
while True:
try:
foo2()
except:
pass
else:
break
And if you want to pass the exception up the chain, just do this in the outer function instead of the inner function:
def queryRepeatedly():
while True:
while True:
try:
foo()
bar()
baz()
except:
pass
else:
break
time.sleep(15)
def foo():
foo2()
All that indentation is a little hard to read, but it's easy to refactor this:
def queryAttempt()
foo()
bar()
baz()
def queryOnce():
while True:
try:
queryAttempt()
except:
pass
else:
break
def queryRepeatedly():
while True:
queryOnce()
time.sleep(15)
But if you think about it, you can also merge the two while
loops into one. The use of continue
may be a bit confusing, but see if you like it better:
def queryRepeatedly():
while True:
try:
foo()
bar()
baz()
except:
continue
time.sleep(15)