26.02.2025 11:52, Andrey Borodin wrote: >> On 25 Feb 2025, at 20:19, Alexander Korotkov <aekorot...@gmail.com> wrote: >> >> > > > Hi! > > One little piece of code looks suspicious to me. But I was not raising > concern because I see similar code everywhere in the codebase. But know > Kirill asked to me explain what is going on and I cannot. > > This seems to be relevant… so. > > + while (upto >= pg_atomic_read_u64(&XLogCtl->InitializedUpTo)) > // Assume ConditionVariableBroadcast() happened here, but before next line > + ConditionVariableSleep(&XLogCtl->InitializedUpToCondVar, > WAIT_EVENT_WAL_BUFFER_INIT); > + ConditionVariableCancelSleep(); > > Won’t this sleep wait forever?
Because ConditionVariableSleep doesn't sleep for the first time. It just performs ConditionVariablePrepareToSleep and immediately returns. So actual condition of `while` loop is checked at least twice before going to sleep. > > I see about 20 other occurrences of similar code, so, perhaps, everything is > fine. But I would greatly appreciate a little pointers on why it works. ------- regards Yura Sokolov aka funny-falcon
