Michael, On Fri, Oct 27, 2023 at 9:52 AM Michael Paquier <mich...@paquier.xyz> wrote: > > On Tue, May 23, 2023 at 01:47:52PM +0300, Aleksander Alekseev wrote: > > That's me still talking to myself :) > > Let's be two then.
Many thanks for your feedback. > + <para> > + It is convenient to use <literal>shmem_startup_hook</literal> which > allows > + placing all the code responsible for initializing shared memory in one > place. > + When using <literal>shmem_startup_hook</literal> the extension still > needs > + to acquire <function>AddinShmemInitLock</function> in order to work > properly > + on all the supported platforms including Windows. > > Yeah, AddinShmemInitLock is useful because extensions have no base > point outside that, and they may want to update their local variables. > Still, this is not completely exact because EXEC_BACKEND on > non-Windows platform would still need it, so this should be mentioned. > Another thing is that extensions may do like autoprewarm.c, where > the shmem area is not initialized in the startup shmem hook. This is > a bit cheating because this is a scenario where shmem_request_hook is > not requested, so shmem needs overallocation, but you'd also need a > LWLock in this case, even for non-WIN32. Got it. Let's simply remove the "including Windows" part then. > > + on all the supported platforms including Windows. This is also the reason > + why the return value of <function>GetNamedLWLockTranche</function> is > + conventionally stored in shared memory instead of local process memory. > + </para> > > Not sure to follow this sentence, the result of GetNamedLWLockTranche > is the lock, so this sentence does not seem really necessary? To be honest, by now I don't remember what was meant here, so I removed the sentence. > While we're on it, why not improving this part of the documentation more > modern? We don't mention LWLockNewTrancheId() and > LWLockRegisterTranche() at all, so do you think that it would be worth > adding a sample of code with that, mentioning autoprewarm.c as > example? Agree, these functions deserve to be mentioned in this section. PFA patch v4. -- Best regards, Aleksander Alekseev
v4-0001-Clarify-the-38.10.10.-Shared-Memory-and-LWLocks-s.patch
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