When a BGSAVE fails, Redis used to flood itself trying to BGSAVE at
every next cron call, that is either 10 or 100 times per second
depending on configuration and server version.
This commit does not allow a new automatic BGSAVE attempt to be
performed before a few seconds delay (currently 5).
This avoids both the auto-flood problem and filling the disk with
logs at a serious rate.
The five seconds limit, considering a log entry of 200 bytes, will use
less than 4 MB of disk space per day that is reasonable, the sysadmin
should notice before of catastrofic events especially since by default
Redis will stop serving write queries after the first failed BGSAVE.
This fixes issue #849
When a BGSAVE fails, Redis used to flood itself trying to BGSAVE at
every next cron call, that is either 10 or 100 times per second
depending on configuration and server version.
This commit does not allow a new automatic BGSAVE attempt to be
performed before a few seconds delay (currently 5).
This avoids both the auto-flood problem and filling the disk with
logs at a serious rate.
The five seconds limit, considering a log entry of 200 bytes, will use
less than 4 MB of disk space per day that is reasonable, the sysadmin
should notice before of catastrofic events especially since by default
Redis will stop serving write queries after the first failed BGSAVE.
This fixes issue #849
This commit fixes two corner cases for the TTL command.
1) When the key was already logically expired (expire time older
than current time) the command returned -1 instead of -2.
2) When the key was existing and the expire was found to be exactly 0
(the key was just about to expire), the command reported -1 (that is, no
expire) instead of a TTL of zero (that is, about to expire).
This commit fixes two corner cases for the TTL command.
1) When the key was already logically expired (expire time older
than current time) the command returned -1 instead of -2.
2) When the key was existing and the expire was found to be exactly 0
(the key was just about to expire), the command reported -1 (that is, no
expire) instead of a TTL of zero (that is, about to expire).
MULTI/EXEC is now propagated to the AOF / Slaves only once we encounter
the first command that is not a read-only one inside the transaction.
The old behavior was to always propagate an empty MULTI/EXEC block when
the transaction was composed just of read only commands, or even
completely empty. This created two problems:
1) It's a bandwidth waste in the replication link and a space waste
inside the AOF file.
2) We used to always increment server.dirty to force the propagation of
the EXEC command, resulting into triggering RDB saves more often
than needed.
Note: even read-only commands may also trigger writes that will be
propagated, when we access a key that is found expired and Redis will
synthesize a DEL operation. However there is no need for this to stay
inside the transaction itself, but only to be ordered.
So for instance something like:
MULTI
GET foo
SET key zap
EXEC
May be propagated into:
DEL foo
MULTI
SET key zap
EXEC
While the DEL is outside the transaction, the commands are delivered in
the right order and it is not possible for other commands to be inserted
between DEL and MULTI.
MULTI/EXEC is now propagated to the AOF / Slaves only once we encounter
the first command that is not a read-only one inside the transaction.
The old behavior was to always propagate an empty MULTI/EXEC block when
the transaction was composed just of read only commands, or even
completely empty. This created two problems:
1) It's a bandwidth waste in the replication link and a space waste
inside the AOF file.
2) We used to always increment server.dirty to force the propagation of
the EXEC command, resulting into triggering RDB saves more often
than needed.
Note: even read-only commands may also trigger writes that will be
propagated, when we access a key that is found expired and Redis will
synthesize a DEL operation. However there is no need for this to stay
inside the transaction itself, but only to be ordered.
So for instance something like:
MULTI
GET foo
SET key zap
EXEC
May be propagated into:
DEL foo
MULTI
SET key zap
EXEC
While the DEL is outside the transaction, the commands are delivered in
the right order and it is not possible for other commands to be inserted
between DEL and MULTI.
