On 16/05/12 11:39, Heikki Linnakangas wrote:
One of the issues we've been looking at with PostGIS is how to interrupt
long-running processing tasks in external libraries, particularly GEOS.
After a few tests here, it seems that even the existing SIGALRM handler
doesn't get called if statement_timeout is reached when in an external
library, e.g. with PostgreSQL 9.0/PostGIS 2.0 trunk/GEOS:
If you interrupt an external library call, it might leave memory in an
inconsistent state, or some other such thing. It's not generally safe to
interrupt arbitrary 3rd party code.
However, if you're absolutely positively sure that the library function
can tolerate that, you can set "ImmediateInterruptOK = true" before
calling it. See e.g PGSemaphoreLock() on how that's done before starting
to sleep on a semapgore.
Hi Heikki,
Yes that appears to work fine on the surface - just testing now to
determine what state everything is left in when queries are aborted
prematurely.
Many thanks,
Mark.
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