When empty strings are created, or when sdsMakeRoomFor() is called, we
are likely into an appending pattern. Use at least type 8 SDS strings
since TYPE 5 does not remember the free allocation size and requires to
call sdsMakeRoomFor() at every new piece appended.
When empty strings are created, or when sdsMakeRoomFor() is called, we
are likely into an appending pattern. Use at least type 8 SDS strings
since TYPE 5 does not remember the free allocation size and requires to
call sdsMakeRoomFor() at every new piece appended.
The previos attempt to process each client at least once every ten
seconds was not a good idea, because:
1. Usually because of the past min iterations set to 50, you get much
better processing period most of the times.
2. However when there are many clients and a normal setting for
server.hz, the edge case is triggered, and waiting 10 seconds for a
BLPOP that asked for 1 second is not ok.
3. Moreover, because of the high min-itereations limit of 50, when HZ
was set to an high value, the actual behavior was to process a lot of
clients per second.
Also the function checking for timeouts called gettimeofday() at each
iteration which can be costly.
The new implementation will try to process each client once per second,
gets the current time as argument, and does not attempt to process more
than 5 clients per iteration if not needed.
So now:
1. The CPU usage of an idle Redis process is the same or better.
2. The CPU usage of a busy Redis process is the same or better.
3. However a non trivial amount of work may be performed per iteration
when there are many many clients. In this particular case the user may
want to raise the "HZ" value if needed.
Btw with 4000 clients it was still not possible to noticy any actual
latency created by processing 400 clients per second, since the work
performed for each client is pretty small.
The previos attempt to process each client at least once every ten
seconds was not a good idea, because:
1. Usually because of the past min iterations set to 50, you get much
better processing period most of the times.
2. However when there are many clients and a normal setting for
server.hz, the edge case is triggered, and waiting 10 seconds for a
BLPOP that asked for 1 second is not ok.
3. Moreover, because of the high min-itereations limit of 50, when HZ
was set to an high value, the actual behavior was to process a lot of
clients per second.
Also the function checking for timeouts called gettimeofday() at each
iteration which can be costly.
The new implementation will try to process each client once per second,
gets the current time as argument, and does not attempt to process more
than 5 clients per iteration if not needed.
So now:
1. The CPU usage of an idle Redis process is the same or better.
2. The CPU usage of a busy Redis process is the same or better.
3. However a non trivial amount of work may be performed per iteration
when there are many many clients. In this particular case the user may
want to raise the "HZ" value if needed.
Btw with 4000 clients it was still not possible to noticy any actual
latency created by processing 400 clients per second, since the work
performed for each client is pretty small.
This is an attempt to use the refcount feature of the sds.c fork
provided in the Pull Request #2509. A new type, SDS_TYPE_5 is introduced
having a one byte header with just the string length, without
information about the available additional length at the end of the
string (this means that sdsMakeRoomFor() will be required each time
we want to append something, since the string will always report to have
0 bytes available).
More work needed in order to avoid common SDS functions will pay the
cost of this type. For example both sdscatprintf() and sdscatfmt()
should try to upgrade to SDS_TYPE_8 ASAP when appending chars.
This is an attempt to use the refcount feature of the sds.c fork
provided in the Pull Request #2509. A new type, SDS_TYPE_5 is introduced
having a one byte header with just the string length, without
information about the available additional length at the end of the
string (this means that sdsMakeRoomFor() will be required each time
we want to append something, since the string will always report to have
0 bytes available).
More work needed in order to avoid common SDS functions will pay the
cost of this type. For example both sdscatprintf() and sdscatfmt()
should try to upgrade to SDS_TYPE_8 ASAP when appending chars.
The command reports information about the hash table internal state
representing the specified database ID.
This can be used in order to investigate rehashings, memory usage issues
and for other debugging purposes.
The command reports information about the hash table internal state
representing the specified database ID.
This can be used in order to investigate rehashings, memory usage issues
and for other debugging purposes.
The new return value is the number of keys existing, among the ones
specified in the command line, counting the same key multiple times if
given multiple times (and if it exists).
See PR #2667.
The new return value is the number of keys existing, among the ones
specified in the command line, counting the same key multiple times if
given multiple times (and if it exists).
See PR #2667.
Rationale:
1. The commands look like internals exposed without a real strong use
case.
2. Whatever there is an use case, the client would implement the
commands client side instead of paying RTT just to use a simple to
reimplement library.
3. They add complexity to an otherwise quite straightforward API.
So for now KILLED ;-)
Rationale:
1. The commands look like internals exposed without a real strong use
case.
2. Whatever there is an use case, the client would implement the
commands client side instead of paying RTT just to use a simple to
reimplement library.
3. They add complexity to an otherwise quite straightforward API.
So for now KILLED ;-)
