The tail size of c->reply is 16kb, but in the test only publish a
few chars each time, due to a change in #8699, the obuf limit
is now checked a new memory allocation is made, so this test
would have sometimes failed to trigger a soft limit disconnection
in time.
The solution is to write bigger payloads to the output buffer, but
still limit their rate (not more than 100k/s).
Before this commit, we would have continued to add replies to the reply buffer even if client
output buffer limit is reached, so the used memory would keep increasing over the configured limit.
What's more, we shouldn’t write any reply to the client if it is set 'CLIENT_CLOSE_ASAP' flag
because that doesn't conform to its definition and we will close all clients flagged with
'CLIENT_CLOSE_ASAP' in ‘beforeSleep’.
Because of code execution order, before this, we may firstly write to part of the replies to
the socket before disconnecting it, but in fact, we may can’t send the full replies to clients
since OS socket buffer is limited. But this unexpected behavior makes some commands work well,
for instance ACL DELUSER, if the client deletes the current user, we need to send reply to client
and close the connection, but before, we close the client firstly and write the reply to reply
buffer. secondly, we shouldn't do this despite the fact it works well in most cases.
We add a flag 'CLIENT_CLOSE_AFTER_COMMAND' to mark clients, this flag means we will close the
client after executing commands and send all entire replies, so that we can write replies to
reply buffer during executing commands, send replies to clients, and close them later.
We also fix some implicit problems. If client output buffer limit is enforced in 'multi/exec',
all commands will be executed completely in redis and clients will not read any reply instead of
partial replies. Even more, if the client executes 'ACL deluser' the using user in 'multi/exec',
it will not read the replies after 'ACL deluser' just like before executing 'client kill' itself
in 'multi/exec'.
We added some tests for output buffer limit breach during multi-exec and using a pipeline of
many small commands rather than one with big response.
Co-authored-by: Oran Agra <oran@redislabs.com>
Now clients that are ready to be terminated asynchronously are processed
more often in beforeSleep() instead of being processed in serverCron().
This means that the test will not be able to catch the moment the client
was terminated, also note that the 'omem' figure now changes in big
steps, because of the new client output buffers layout.
So we have to change the test range in order to accomodate for that.
Yet the test is useful enough to be worth taking, even if its precision
is reduced by this commit. Probably if we get more problems, a thing
that makes sense is just to check that the limit is < 200k. That's more
than enough actually.
