GoDaddy: undocumented 20-second CPU time maximal execution limit? (python, ELF, etc)
16th October 2007
Today, setting up a relatively serious (in CPU resources needed) web-system, I ran into a weird problem of python scripts ending prematurely. After some investigation, it looked like any process which uses up more than 20 seconds of CPU time, is automatically killed. To verify this, I wrote an infinite loop in C,
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int main () {
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unsigned int i;
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for (i = 0; i <2 ; i++ ) {
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i = 0;
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}
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return 0;
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}
compiled it and executed several times on the GoDaddy shared hosting server. I did observe the program running for the maximum of 20 seconds of CPU time, not a second more. Please note, that 20 seconds of CPU time can be much more of "real" time, if the script isn't using 100% of CPU, which often the case for shared hosting. Thus if you have in your php.ini max_execution_time set to, say, 60 seconds, your php script may actually execute as long as one minute; but I'm pretty sure that if your script has lots of CPU-intensive procedures, then as soon as it uses 20 seconds of CPU time, it will be terminated (however, this statement still needs checking - anyone?).
To verify, I also created a cron job with the same file. It ran for 30 seconds CPU time.
Strangely, this behaviour is not documented anywhere.
This limit may also explain a number of other problems, if you have heavy web-applications: they just might be killed before they are finished, causing errors.
I do understand the reason for this limitation, and am sure similar limitations exist in other shared hosting environments. The only important thing here is that this limit should have been documented and even put upfront somewhere in the hosting plans descriptions.
I also wonder if the limit is the same for all godaddy shared hosting plans, or if it differs. 20 seconds when executed from PHP, and 30 seconds when executed as a cron job were observed on the Deluxe Linux Hosting plan.
Extensions, additions and comments are welcome.
October 19th, 2007 at 16:18
[...] GoDaddy: undocumented 20-second CPU time maximal execution limit? (python, ELF, etc) [...]
June 4th, 2008 at 18:51
[...] it’s better to have a 125MHz-clamp on CPU, than have a 20-seconds maximal CPU time limit [...]
October 19th, 2008 at 7:01
I guess you could probably try this out with a PHP script which has code like below:
sleep(10);
echo 'The script has been running for 10 seconds';
sleep(10);
echo 'the script has been running for 20 seconds';
sleep(10);
echo 'the script has been running for 30 seconds';
Etcetera? Not sure, just an idea.
Cheers,
Sid
October 19th, 2008 at 10:46
Sid,
that won't show anything, as "sleeping" doesn't consume CPU time as actively as an infinite loop - so this just is not the CPU time you would be trying to measure with this PHP script.
Moreover, as my little experiment with an infinite loop did work, there is no need in any additional testing.
October 19th, 2008 at 15:55
Ah, I did not realise the difference.
I'm on GoDaddy right now, and my scripts seem to be running fairly well, and Wordpress 2.6 with decent speed, although I noticed that the Deluxe plan had better performance than my Economy hosting plan, although this might have been a placebo.
Anyways,
Cheers,
Sid