FWIW there's a stupid bug in 0002, which is fixed here. I'm writing a simple test for it.
-- Álvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/ "Now I have my system running, not a byte was off the shelf; It rarely breaks and when it does I fix the code myself. It's stable, clean and elegant, and lightning fast as well, And it doesn't cost a nickel, so Bill Gates can go to hell."
>From ecf613092a3cbc4c5112d30af7eea55b668decec Mon Sep 17 00:00:00 2001 From: Alvaro Herrera <[email protected]> Date: Mon, 4 Mar 2024 11:49:01 +0100 Subject: [PATCH v3] Rework redundant loop in subtrans.c --- src/backend/access/transam/subtrans.c | 29 +++++++-------------------- 1 file changed, 7 insertions(+), 22 deletions(-) diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c index dc9566fb51..50bb1d8cfc 100644 --- a/src/backend/access/transam/subtrans.c +++ b/src/backend/access/transam/subtrans.c @@ -311,7 +311,7 @@ StartupSUBTRANS(TransactionId oldestActiveXID) FullTransactionId nextXid; int64 startPage; int64 endPage; - LWLock *prevlock; + LWLock *prevlock = NULL; LWLock *lock; /* @@ -324,42 +324,27 @@ StartupSUBTRANS(TransactionId oldestActiveXID) nextXid = TransamVariables->nextXid; endPage = TransactionIdToPage(XidFromFullTransactionId(nextXid)); - prevlock = SimpleLruGetBankLock(SubTransCtl, startPage); - LWLockAcquire(prevlock, LW_EXCLUSIVE); - while (startPage != endPage) + for (;;) { lock = SimpleLruGetBankLock(SubTransCtl, startPage); - - /* - * Check if we need to acquire the lock on the new bank then release - * the lock on the old bank and acquire on the new bank. - */ if (prevlock != lock) { - LWLockRelease(prevlock); + if (prevlock) + LWLockRelease(prevlock); LWLockAcquire(lock, LW_EXCLUSIVE); prevlock = lock; } (void) ZeroSUBTRANSPage(startPage); + if (startPage == endPage) + break; + startPage++; /* must account for wraparound */ if (startPage > TransactionIdToPage(MaxTransactionId)) startPage = 0; } - lock = SimpleLruGetBankLock(SubTransCtl, startPage); - - /* - * Check if we need to acquire the lock on the new bank then release the - * lock on the old bank and acquire on the new bank. - */ - if (prevlock != lock) - { - LWLockRelease(prevlock); - LWLockAcquire(lock, LW_EXCLUSIVE); - } - (void) ZeroSUBTRANSPage(startPage); LWLockRelease(lock); } -- 2.39.2
