Re: Something fishy happening on frogmouth

On 31.10.2013 16:43, Robert Haas wrote:
> Let me say this again: the dynamic shared memory code *does* clean up
> after itself.  If you kill -9 the postmaster and all of its children,
> you'll orphan the main shared memory segment and any dynamic shared
> memory segments that exist.  There is nothing we can do about that.
> When you restart the postmaster, both the main shared memory segment
> and any dynamic shared memory segments orphaned by the previous kill
> will be cleaned up.  I spent a lot of time trying to make sure that
> the handling of dynamic shared memory segments is, in all cases, as
> parallel to the handling of the main shared memory segment as
> possible.  There should be no cases where the main shared memory
> segment gets cleaned up and the dynamic shared memory segments do not.

1. initdb -D data1
2. initdb -D data2
3. postgres -D data1
4. killall -9 postgres
5. postgres -D data2

The system V shmem segment orphaned at step 4 will be cleaned up at step 
5. The DSM segment will not.

BTW, 9.3 actually made the situation a lot better for the main memory 
segment. You only leak the small interlock shmem segment, the large 
mmap'd block does get automatically free'd when the last process using 
it exits.

- Heikki