On Wed, Jul 17, 2019 at 7:08 PM Tom Lane <
tgl@sss.pgh.pa.us> wrote:
>
> Asim R P <
apraveen@pivotal.io> writes:
> > Cancel/terminate requests are held off during "PREPARE TRANSACTION"
> > processing in function PrepareTransaction(). However, a subroutine invoked
> > by PrepareTransaction() may perform elog(ERROR) or elog(FATAL).
>
> The correct response, if you notice code doing that, is to fix it so
> it doesn't do that. Typically the right answer is to move the
> failure-prone operation to pre-commit processing.
Thank you for the response. There is nothing particularly alarming. There is one case in LWLockAcquire that may error out if (num_held_lwlocks >= MAX_SIMUL_LWLOCKS). This problem also exists in CommitTransaction() and AbortTransaction() code paths. Then there is arbitrary add-on code registered as Xact_callbacks.
SyncRepWaitForLSN() directly checks ProcDiePending and QueryCancelPending without going through CHECK_FOR_INTERRUPTS and that is for good reason. Moreover, it only emits a WARNING, so no problem there.
Asim