On Wed, May 17, 2017 at 1:30 AM, Robert Haas <robertmh...@gmail.com> wrote:
> On Sat, May 13, 2017 at 7:27 AM, Amit Kapila <amit.kapil...@gmail.com> wrote:
>> On Fri, May 12, 2017 at 9:14 AM, Tom Lane <t...@sss.pgh.pa.us> wrote:
>>> Robert Haas <robertmh...@gmail.com> writes:
>>>> On Wed, May 10, 2017 at 8:39 PM, Masahiko Sawada <sawada.m...@gmail.com> 
>>>> wrote:
>>>>> ... I'd like to propose to change relation
>>>>> extension lock management so that it works using LWLock instead.
>>>> That's not a good idea because it'll make the code that executes while
>>>> holding that lock noninterruptible.
>>> Is that really a problem?  We typically only hold it over one kernel call,
>>> which ought to be noninterruptible anyway.
>> During parallel bulk load operations, I think we hold it over multiple
>> kernel calls.
> We do.  Also, RelationGetNumberOfBlocks() is not necessarily only one
> kernel call, no?  Nor is vm_extend.

Yeah, these functions could call more than one kernel calls while
holding extension lock.

> Also, it's not just the backend doing the filesystem operation that's
> non-interruptible, but also any waiters, right?
> Maybe this isn't a big problem, but it does seem to be that it would
> be better to avoid it if we can.

I agree to change it to be interruptible for more safety.


Masahiko Sawada
NTT Open Source Software Center

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