From: Amit Kapila <amit.kapil...@gmail.com> > Why would all client backends wait for AccessExclusive lock on this > relation? Say, a client needs a buffer for some other relation and > that might evict this buffer after we release the lock on the > partition. In StrategyGetBuffer, it is important to either have a pin > on the buffer or the buffer header itself must be locked to avoid > getting picked as victim buffer. Am I missing something?
Ouch, right. (The year-end business must be making me crazy...) So, there are two choices here: 1) The current patch. 2) Acquire the buffer header spinlock before releasing the buffer mapping lwlock, and eliminate the buffer tag comparison as follows: BufTableLookup(); LockBufHdr(); LWLockRelease(); InvalidateBuffer(); I think both are okay. If I must choose either, I kind of prefer 1), because LWLockRelease() could take longer time to wake up other processes waiting on the lwlock, which is not very good to do while holding a spinlock. Regards Takayuki Tsunakawa
