Funcion adjustOpenFilesLimit() has an implicit parameter, which is server.maxclients.
This function aims to ajust maximum file descriptor number according to server.maxclients
by best effort, which is "bestlimit" could be lower than "maxfiles" but greater than "oldlimit".
When we try to increase "maxclients" using CONFIG SET command, we could increase maximum
file descriptor number to a bigger value without calling aeResizeSetSize the same time.
When later more and more clients connect to server, the allocated fd could be bigger and bigger,
and eventually exceeds events size of aeEventLoop.events. When new nodes joins the cluster,
new link is created, together with new fd, but when calling aeCreateFileEvent, we did not
check the return value. In this case, we have a non-null "link" but the associated fd is not
registered.
So when we dynamically set "maxclients" we could reach an inconsistency between maximum file
descriptor number of the process and server.maxclients. And later could cause cluster link and link
fd inconsistency.
While setting "maxclients" dynamically, we consider it as failed when resulting "maxclients" is not
the same as expected. We try to restore back the maximum file descriptor number when we failed to set
"maxclients" to the specified value, so that server.maxclients could act as a guard as before.
This bug is from the first version of Redis. Probably the problem here
is that before we used an SDS split function that created empty strings
for additional spaces, like in "SET foo bar".
AFAIK later we replaced it with the curretn sdssplitarg() API that has
no such a problem. As a result, we introduced a bug, where it is no
longer possible to do something like:
SET foo ""
Using the inline protocol. Now it is fixed.
- make lua-replicate-commands mutable (it never was, but i don't see why)
- make tcp-backlog immutable (fix a recent refactory mistake)
- increase the max limit of a few configs to match what they were before
the recent refactory
This commit solves several edge cases that are related to
exhausting the streamID limits: We should correctly calculate
the succeeding streamID instead of blindly incrementing 'seq'
This affects both XREAD and XADD.
Other (unrelated) changes:
Reply with a better error message when trying to add an entry
to a stream that has exhausted last_id
With the previous API, a NULL return value was ambiguous and could
represent either an old value of NULL or an error condition. The new API
returns a status code and allows the old value to be returned
by-reference.
This commit also includes test coverage based on
tests/modules/datatype.c which did not exist at the time of the original
commit.
since the refactory of config.c, it was initialized from config_hz in initServer
but apparently that's too late since the config file loading creates objects
which call LRU_CLOCK
This is useful to tell redis and modules to try to avoid doing things that may
increment the replication offset, and should be used when draining a master
and waiting for replicas to be in perfect sync before a failover.
