Writers won't queue up, rather they'll storm the place, taking turns at asking “can I go now” and sleeping for (tens, hundreds of) milliseconds at a time. This

Writers won't queue up, rather they'll storm the place, taking turns at asking “can I go now” and sleeping for (tens, hundreds of) milliseconds at a time. This only gets “worse” as computers get faster: imagine how many write transactions a serial writer could complete (WAL mode and normal synchronous mode) while all your writers are sleeping after the previous one left, because they didn't line up? And, if you have a single limited pool, your readers will now be stuck waiting for an available connection too (because they're all taken by sleeping writers). It's much fairer and more efficient for writers to line up with blocking application locks.