1. 30 Apr, 2013 4 commits
    • antirez's avatar
      Redis 2.6.13 · d9649796
      antirez authored
      d9649796
    • antirez's avatar
      Sentinel: changes to tilt mode. · 4f38d032
      antirez authored
      Tilt mode was too aggressive (not processing INFO output), this
      resulted in a few problems:
      
      1) Redirections were not followed when in tilt mode. This opened a
         window to misinform clients about the current master when a Sentinel
         was in tilt mode and a fail over happened during the time it was not
         able to update the state.
      
      2) It was possible for a Sentinel exiting tilt mode to detect a false
         fail over start, if a slave rebooted with a wrong configuration
         about at the same time. This used to happen since in tilt mode we
         lose the information that the runid changed (reboot).
      
         Now instead the Sentinel in tilt mode will still remove the instance
         from the list of slaves if it changes state AND runid at the same
         time.
      
      Both are edge conditions but the changes should overall improve the
      reliability of Sentinel.
      4f38d032
    • antirez's avatar
      59ff2fe9
    • antirez's avatar
      Sentinel: only demote old master into slave under certain conditions. · fb0d08e3
      antirez authored
      We used to always turn a master into a slave if the DEMOTE flag was set,
      as this was a resurrecting master instance.
      
      However the following race condition is possible for a Sentinel that
      got partitioned or internal issues (tilt mode), and was not able to
      refresh the state in the meantime:
      
      1) Sentinel X is running, master is instance "A".
      3) "A" fails, sentinels will promote slave "B" as master.
      2) Sentinel X goes down because of a network partition.
      4) "A" returns available, Sentinels will demote it as a slave.
      5) "B" fails, other Sentinels will promote slave "A" as master.
      6) At this point Sentinel X comes back.
      
      When "X" comes back he thinks that:
      
      "B" is the master.
      "A" is the slave to demote.
      
      We want to avoid that Sentinel "X" will demote "A" into a slave.
      We also want that Sentinel "X" will detect that the conditions changed
      and will reconfigure itself to monitor the right master.
      
      There are two main ways for the Sentinel to reconfigure itself after
      this event:
      
      1) If "B" is reachable and already configured as a slave by other
      sentinels, "X" will perform a redirection to "A".
      2) If there are not the conditions to demote "A", the fact that "A"
      reports to be a master will trigger a failover detection in "X", that
      will end into a reconfiguraiton to monitor "A".
      
      However if the Sentinel was not reachable, its state may not be updated,
      so in case it titled, or was partiitoned from the master instance of the
      slave to demote, the new implementation waits some time (enough to
      guarantee we can detect the new INFO, and new DOWN conditions).
      
      If after some time still there are not the right condiitons to demote
      the instance, the DEMOTE flag is cleared.
      fb0d08e3
  2. 24 Apr, 2013 4 commits
    • antirez's avatar
      Sentinel: always redirect on master->slave transition. · 34a57a5b
      antirez authored
      Sentinel redirected to the master if the instance changed runid or it
      was the first time we got INFO, and a role change was detected from
      master to slave.
      
      While this is a good idea in case of slave->master, since otherwise we
      could detect a failover without good reasons just after a reboot with a
      slave with a wrong configuration, in the case of master->slave
      transition is much better to always perform the redirection for the
      following reasons:
      
      1) A Sentinel may go down for some time. When it is back online there is
      no other way to understand there was a failover.
      2) Pointing clients to a slave seems to be always the wrong thing to do.
      3) There is no good rationale about handling things differently once an
      instance is rebooted (runid change) in that case.
      34a57a5b
    • antirez's avatar
      967ae8ca
    • antirez's avatar
      AOF: sync data on disk every 32MB when rewriting. · c735116c
      antirez authored
      This prevents the kernel from putting too much stuff in the output
      buffers, doing too heavy I/O all at once. So the goal of this commit is
      to split the disk pressure due to the AOF rewrite process into smaller
      spikes.
      
      Please see issue #1019 for more information.
      c735116c
    • antirez's avatar
  3. 22 Apr, 2013 1 commit
  4. 19 Apr, 2013 1 commit
  5. 11 Apr, 2013 2 commits
    • antirez's avatar
      redis-cli: raise error on bad command line switch. · 40861516
      antirez authored
      Previously redis-cli never tried to raise an error when an unrecognized
      switch was encountered, as everything after the initial options is to be
      transmitted to the server.
      
      However this is too liberal, as there are no commands starting with "-".
      So the new behavior is to produce an error if there is an unrecognized
      switch starting with "-". This should not break past redis-cli usages
      but should prevent broken options to be silently discarded.
      
      As far the first token not starting with "-" is encountered, all the
      rest is considered to be part of the command, so you cna still use
      strings starting with "-" as values, like in:
      
          redis-cli --port 6380 set foo --my-value
      40861516
    • antirez's avatar
      redis-cli: --latency-history mode implemented. · 92a7b010
      antirez authored
      92a7b010
  6. 03 Apr, 2013 1 commit
  7. 02 Apr, 2013 1 commit
    • antirez's avatar
      Throttle BGSAVE attempt on saving error. · ed2d9881
      antirez authored
      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
      ed2d9881
  8. 29 Mar, 2013 2 commits
  9. 28 Mar, 2013 4 commits
  10. 27 Mar, 2013 4 commits
    • antirez's avatar
      Flag PUBLISH as read-only in the command table. · 6cb78606
      antirez authored
      6cb78606
    • antirez's avatar
      Transactions: propagate MULTI/EXEC only when needed. · 611dcb56
      antirez authored
      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.
      611dcb56
    • antirez's avatar
      889b0174
    • antirez's avatar
      Transactions: use the propagate() API to propagate MULTI. · d1369c3d
      antirez authored
      The behavior is the same, but the code is now cleaner and uses the
      proper interface instead of dealing directly with AOF/replication
      functions.
      d1369c3d
  11. 26 Mar, 2013 1 commit
  12. 25 Mar, 2013 2 commits
    • NanXiao's avatar
      Update config.c · ef1cf15c
      NanXiao authored
      Fix bug in configGetCommand function: get correct masterauth value.
      ef1cf15c
    • antirez's avatar
      redis-cli --stat, stolen from redis-tools. · 5576a289
      antirez authored
      Redis-tools is a connection of tools no longer mantained that was
      intented as a way to economically make sense of Redis in the pre-vmware
      sponsorship era. However there was a nice redis-stat utility, this
      commit imports one of the functionalities of this tool here in redis-cli
      as it seems to be pretty useful.
      
      Usage: redis-cli --stat
      
      The output is similar to vmstat in the format, but with Redis specific
      stuff of course.
      
      From the point of view of the monitored instance, only INFO is used in
      order to grab data.
      5576a289
  13. 13 Mar, 2013 3 commits
  14. 12 Mar, 2013 2 commits
  15. 11 Mar, 2013 8 commits