On Wed, Feb 10, 2016 at 1:32 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > The reason for using centralized way is that we need to request > named tranches before initialization of shared memory and as far as > I can see, currently there is no way in the subsystems where they can > issue such a request, so one possibility is that we introduce new API's > like InitBufferLWLocks(), InitLmgrLWLocks(), InitPredicateLWLocks() > in respective subsystem and call them in > CreateSharedMemoryAndSemaphores() before shared memory > initialization. Does by doing that way addresses your concern?
Well, if we're going to have new functions like that, I think the place to call them from is PostmasterMain() just before process_shared_preload_libraries(). After all, if extensions were requesting tranches, they'd do it from process_shared_preload_libraries(), so it seems like the right place. However, since the number of locks we need for each of these subsystems is fixed at compile time, it seems a bit of a shame to have to do something about them at runtime. I wonder if we should just hard-code this in CreateLWLocks() instead of trying to use the named-tranche facility. That is, where that function does this: MainLWLockTranche.name = "main"; MainLWLockTranche.array_base = MainLWLockArray; MainLWLockTranche.array_stride = sizeof(LWLockPadded); LWLockRegisterTranche(LWTRANCHE_MAIN, &MainLWLockTranche); ...register four tranches instead. And where it does this: /* Initialize all fixed LWLocks in main array */ for (id = 0, lock = MainLWLockArray; id < numLocks; id++, lock++) LWLockInitialize(&lock->lock, LWTRANCHE_MAIN); ...have four loops instead, each initializing with a different tranche ID. Then the current method of computing the location of those locks would still work just fine; the code changes would be a lot more isolated, and we wouldn't have to do runtime save-and-restore of more variables on Windows. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers