When WRITE lock attemp fails (exclusive lock for ALTER/DELETE), and
there are multiple READ locks (shared lock for SELECT/INSERT), i.e. one
INSERT is in progress and one SELECT is queued after ALTER/DELETE
started but before it fails, this SELECT will wait until INSERT will
finishes.
This happens because in case of WRITE lock failure it does not notify
the next READ lock that can be acquired.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
