Re: Relations being opened without any lock whatever

Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> writes:
> On 2018/10/01 4:20, Tom Lane wrote:
>> Running the regression tests with the patch I showed in
>> https://www.postgresql.org/message-id/16565.1538327894@sss.pgh.pa.us

> Maybe you've noticed but the relation_open calls coming from bootstrap.c
> all pass NoLock which trigger the WARNING:

Yeah, I'd missed noticing that at the time I posted that patch, but I
sure noticed after changing the WARNING to an Assert ;-)

> Do we need to do something about that, like teaching boot_openrel() and
> gettype() in bootstrap.c to pass AccessShareLock instead of NoLock?

No, bootstrap mode has no need for locking.  I think the right fix is
just to skip the check:
 
+    /*
+     * If we didn't get the lock ourselves, assert that caller holds one,
+     * except in bootstrap mode where no locks are used.
+     */
+    Assert(lockmode != NoLock ||
+           IsBootstrapProcessingMode() ||
+           CheckRelationLockedByMe(r, AccessShareLock, true));

It's possible that at some point we'd decide to make bootstrap mode
do locking the same as normal mode, but that's not a change I want
to make as part of this patch.

            regards, tom lane