Thread: server crash on recursive function invocation

<br />hi,<br />i was just trying recursive function invocation and got a server crash when i changed a GUC variable
max_stack_depth, to a high number. <br />fallowing is what i have tried.<br /><br />select max_val from pg_settings
wherename='max_stack_depth'; -- returns 2097151<br />set max_stack_depth=2097151;<br />CREATE OR REPLACE FUNCTION
func()RETURNS INT AS $$<br />DECLARE<br />x int;<br />BEGIN<br />  null;<br />  x := func();<br />  return 0;<br
/>END;<br/>$$ LANGUAGE PLPGSQL;<br />select func();<br /> and the server get crashed.<br /><br /><pre><font><font
face="Arial,Helvetica, sans-serif">Any ideas?<br /><br />Thanks,<br />--Usman<br /></font></font></pre><br /><br /><br
/><br/><br /><p><hr size="1" />Be a chatter box. Enjoy <a
href="http://us.rd.yahoo.com/mail_us/taglines/postman12/*http://us.rd.yahoo.com/evt=39663/*http://messenger.yahoo.com">free
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Ali Baba said:
>
> hi,
> i was just trying recursive function invocation and got a server crash
> when i changed a GUC variable max_stack_depth,  to a high number.
> fallowing is what i have tried.
>
> select max_val from pg_settings where name='max_stack_depth'; --
> returns 2097151 set max_stack_depth=2097151;
> CREATE OR REPLACE FUNCTION func() RETURNS INT AS $$
> DECLARE
> x int;
> BEGIN
>  null;
>  x := func();
>  return 0;
> END;
> $$ LANGUAGE PLPGSQL;
> select func();
> and the server get crashed.
>
>
> Any ideas?
>


what the heck did you expect with an infinitely recursive function?

cheers

andrew

Ali Baba <idofyear@yahoo.com> writes:
> i was just trying recursive function invocation and got a server crash when i changed a GUC variable max_stack_depth,
to a high number. 
 

There's a reason why that variable is a superuser-only setting: you're
supposed to have some clue what you're doing when you change it ;-)

If you need more stack space, what you generally have to do is adjust
the ulimit setting that the postmaster is started under.  You can set
max_stack_depth up to a few hundred K less than the postmaster's
ulimit -s setting, but not more.

(We wouldn't even have the variable if there were a sufficiently
portable way to find out the ulimit stack depth automatically, but
there's not one that I know of.)
        regards, tom lane