I need to write code like this: Do operation 1, but if it takes more that 5 seconds then stop it and do operation 2. Is it possible to do this somehow without manual interruption?
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2 Answers
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You can use TimeConstrained for this. Here is an example
tMax = 1; (*second*)
f1[n_Integer] := Do[i^2, {i, n}];
TimeConstrained[f1[10^7], tMax]
(* $Aborted *)
You can use CheckAbort to check which function timed out or not, since TimeConstrained generated $Aborted. Here is an example
tMax = 5; (*second*)
f1[n_Integer] := Do[i^2, {i, n}];
n = {10^1, 10^6, 10^8};
CheckAbort[TimeConstrained[f1[#], 5, Abort[]], "timed out!"] & /@ n
(* {Null, Null, $Aborted} *)
So the last one timed out, but not the first two. You can customize this more as needed. (I need to find why the message "timed out" did not show up, but will look at this soon)
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$\begingroup$ It looks like
CheckAbortdoesnt see the interrupt caused byTimeConstrained(if you do Alt-. quick enough you get theCheckAbortexpression .. ) $\endgroup$ Commented Jun 13, 2014 at 20:16 -
$\begingroup$ @george2079 yes, something is strange with
CheckAborthere. it should have returned the message. I posted a question on chat now about it. Not relevant to this answer, as one does not have to use it. But it is strange. $\endgroup$– NasserCommented Jun 13, 2014 at 20:19 -
$\begingroup$ @Nasser - just found a horrible solution:
CheckAbort[TimeConstrained[f1[#], 5], ""] & /@ n /. $Aborted -> "timed out!"$\endgroup$– eldoCommented Jun 13, 2014 at 21:15 -
3$\begingroup$ @Nasser:
CheckAbort[TimeConstrained[f1[#], 5, Abort[]], "timed out!"] & /@ n$\endgroup$– ciaoCommented Jun 14, 2014 at 0:37 -
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I would use the 3-arg version of TimeConstrained:
op1[time_] := (Pause[time]; Print[1]; 1)
op2 := (Print[2]; 2)
An example where op1 doesn't time out:
TimeConstrained[op1[2], 3, op2]
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Notice that op2 never evaluates. Next, an example where op1 times out:
TimeConstrained[op1[2], 1, op2]
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This time op1 was aborted, and so it didn't get a chance to print 1, while op2 does evaluate and prints 2.
answered Mar 28, 2019 at 17:59
TimeConstrained. Example from helpTimeConstrained[Do[i^2, {i, 1000000}], 1]will terminate computation if it takes more than one second. You can adjust the time as needed. $\endgroup$Namesis often useful. The first entry forNames["Time*"]would have answered your question. $\endgroup$