On Thu, Sep 04, 2025 at 04:12:09PM -0500, Sami Imseih wrote:
>> Yeah, I think modeling this after commit 4f2400c is a reasonable thing to
>> explore.
>
> Here it is as described above.
Thanks. This looks like the right idea to me, but let's give some time for
others to comment.
--
nathan
> Yeah, I think modeling this after commit 4f2400c is a reasonable thing to
> explore.
Here it is as described above.
--
Sami
v2-0001-Prevent-crash-when-retreiving-LWLock-tranches.patch
Description: Binary data
On Thu, Sep 04, 2025 at 01:23:26PM -0500, Sami Imseih wrote:
> I suggest we set an in progres flag for shmem_startup_hook, as we do for
> shmem_request_hook, and error out this function if called outside of this
> hook. The error will be something like this:
>
> ```
> ERROR: cannot return the add
commit 38b602b certainly doesn't do us any favors here since it
> removed NamedLWLockTrancheArray. Given the lack of reports from the field,
> I suspect the best path forward is to add an ERROR for unsafe accesses and
> to fix the documentation, as discussed upthread.
I suggest we set an in progr
Well, commit 38b602b certainly doesn't do us any favors here since it
removed NamedLWLockTrancheArray. Given the lack of reports from the field,
I suspect the best path forward is to add an ERROR for unsafe accesses and
to fix the documentation, as discussed upthread.
--
nathan
On Mon, Aug 25, 2025 at 04:28:09PM -0500, Sami Imseih wrote:
> Here it is.
Looks reasonable to me. I'll leave this one around for a week or two to
give others a chance to comment.
--
nathan
Here it is.
I was hoping we can even get rid of NamedLWLockTrancheRequests
altogether, but that's not going to be possible because
RequestNamedLWLockTranche happens earlier than
CreateLWLocks, so NamedLWLockTrancheRequests is essentially
tracking the requested lwlocks until we get a chance to crea
> > Another approach is to just change GetNamedLWLockTranche to use
> > NamedLWLockTrancheArray since that is already copied in EXEC_BACKEND, and
> > allow GetNamedLWLockTranche to continue to be used outside of startup. In
> > this case, we will need to add num_lwlocks field to
> > NamedLWLockTran
On Mon, Aug 25, 2025 at 01:44:22PM -0500, Sami Imseih wrote:
> Another approach is to just change GetNamedLWLockTranche to use
> NamedLWLockTrancheArray since that is already copied in EXEC_BACKEND, and
> allow GetNamedLWLockTranche to continue to be used outside of startup. In
> this case, we will
> Attached is a repro patch. You will need to set
> shared_preload_libraries = 'pg_stat_statements'
> as well.
I forgot to mention. Once patched, you can run a simple
select statement from a new connection to force the crash.
This is because GetNamedLWLockTranche will be called
at pgss_ExecutorEnd
> On Mon, Aug 25, 2025 at 12:58:08PM -0500, Sami Imseih wrote:
> >> If this fails, why doesn't the call in pgss_shmem_startup() also fail? Was
> >> pg_stat_statements not loaded via shared_preload_libraries?
> >
> > because the array is valid in postmaster, but it's not for a normal backend,
> > s
On Mon, Aug 25, 2025 at 12:58:08PM -0500, Sami Imseih wrote:
>> If this fails, why doesn't the call in pgss_shmem_startup() also fail? Was
>> pg_stat_statements not loaded via shared_preload_libraries?
>
> because the array is valid in postmaster, but it's not for a normal backend,
> since it's n
> On Fri, Aug 22, 2025 at 02:21:55PM -0500, Sami Imseih wrote:
> > While working on [0], I observed that $SUBJECT. I encountered this issue
> > while building test cases for [0], and in which GetNamedLWLockTranche is
> > called outside of startup.
> >
> > [...]
> >
> > I repro'd this on a Windows m
On Fri, Aug 22, 2025 at 02:21:55PM -0500, Sami Imseih wrote:
> While working on [0], I observed that $SUBJECT. I encountered this issue
> while building test cases for [0], and in which GetNamedLWLockTranche is
> called outside of startup.
>
> [...]
>
> I repro'd this on a Windows machine, but on
Hi,
While working on [0], I observed that $SUBJECT. I encountered this issue
while building test cases for [0], and in which GetNamedLWLockTranche is
called outside of startup.
This crash, reproducible on HEAD, occurs because NamedLWLockTrancheRequestArray
( a local array populated during shmem_r
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