1. 24 May, 2012 1 commit
    • antirez's avatar
      Allow an AOF rewrite buffer > 2GB (Fix for issue #504). · edb95253
      antirez authored
      During the AOF rewrite process, the parent process needs to accumulate
      the new writes in an in-memory buffer: when the child will terminate the
      AOF rewriting process this buffer (that ist the difference between the
      dataset when the rewrite was started, and the current dataset) is
      flushed to the new AOF file.
      
      We used to implement this buffer using an sds.c string, but sds.c has a
      2GB limit. Sometimes the dataset can be big enough, the amount of writes
      so high, and the rewrite process slow enough that we overflow the 2GB
      limit, causing a crash, documented on github by issue #504.
      
      In order to prevent this from happening, this commit introduces a new
      system to accumulate writes, implemented by a linked list of blocks of
      10 MB each, so that we also avoid paying the reallocation cost.
      
      Note that theoretically modern operating systems may implement realloc()
      simply as a remaping of the old pages, thus with very good performances,
      see for instance the mremap() syscall on Linux. However this is not
      always true, and jemalloc by default avoids doing this because there are
      issues with the current implementation of mremap().
      
      For this reason we are using a linked list of blocks instead of a single
      block that gets reallocated again and again.
      
      The changes in this commit lacks testing, that will be performed before
      merging into the unstable branch. This fix will not enter 2.4 because it
      is too invasive. However 2.4 will log a warning when the AOF rewrite
      buffer is near to the 2GB limit.
      edb95253
  2. 14 May, 2012 2 commits
    • antirez's avatar
      Impovements for: Redis timer, hashes rehashing, keys collection. · a8a981a8
      antirez authored
      A previous commit introduced REDIS_HZ define that changes the frequency
      of calls to the serverCron() Redis function. This commit improves
      different related things:
      
      1) Software watchdog: now the minimal period can be set according to
      REDIS_HZ. The minimal period is two times the timer period, that is:
      
          (1000/REDIS_HZ)*2 milliseconds
      
      2) The incremental rehashing is now performed in the expires dictionary
      as well.
      
      3) The activeExpireCycle() function was improved in different ways:
      
      - Now it checks if it already used too much time using microseconds
        instead of milliseconds for better precision.
      - The time limit is now calculated correctly, in the previous version
        the division was performed before of the multiplication resulting in
        a timelimit of 0 if HZ was big enough.
      - Databases with less than 1% of buckets fill in the hash table are
        skipped, because getting random keys is too expensive in this
        condition.
      
      4) tryResizeHashTables() is now called at every timer call, we need to
         match the number of calls we do to the expired keys colleciton cycle.
      
      5) REDIS_HZ was raised to 100.
      a8a981a8
    • antirez's avatar
      Redis timer interrupt frequency configurable as REDIS_HZ. · f7f2b261
      antirez authored
      Redis uses a function called serverCron() that is very similar to the
      timer interrupt of an operating system. This function is used to handle
      a number of asynchronous things, like active expired keys collection,
      clients timeouts, update of statistics, things related to the cluster
      and replication, triggering of BGSAVE and AOF rewrite process, and so
      forth.
      
      In the past the timer was called 1 time per second. At some point it was
      raised to 10 times per second, but it still was fixed and could not be
      changed even at compile time, because different functions called from
      serverCron() assumed a given fixed frequency.
      
      This commmit makes the frequency configurable, so that it is simpler to
      pick a good tradeoff between overhead of this function (that is usually
      very small) and the responsiveness of Redis during a few critical
      circumstances where a lot of work is done inside the timer.
      
      An example of such a critical condition is mass-expire of a lot of keys
      in the same second. Up to a given percentage of CPU time is used to
      perform expired keys collection per expire cylce. Now changing the
      REDIS_HZ macro it is possible to do less work but more times per second
      in order to block the server for less time.
      
      If this patch will work well in our tests it will enter Redis 2.6-final.
      f7f2b261
  3. 12 May, 2012 1 commit
    • antirez's avatar
      More incremental active expired keys collection process. · 3a401464
      antirez authored
      If a large amonut of keys are all expiring about at the same time, the
      "active" expired keys collection cycle used to block as far as the
      percentage of already expired keys was >= 25% of the total population of
      keys with an expire set.
      
      This could block the server even for many seconds in order to reclaim
      memory ASAP. The new algorithm uses at max a small amount of
      milliseconds per cycle, even if this means reclaiming the memory less
      promptly it also means a more responsive server.
      3a401464
  4. 02 May, 2012 1 commit
  5. 21 Apr, 2012 1 commit
    • antirez's avatar
      Limit memory used by big SLOWLOG entries. · 590d55a2
      antirez authored
      Two limits are added:
      
      1) Up to SLOWLOG_ENTRY_MAX_ARGV arguments are logged.
      2) Up to SLOWLOG_ENTRY_MAX_STRING bytes per argument are logged.
      3) slowlog-max-len is set to 128 by default (was 1024).
      
      The number of remaining arguments / bytes is logged in the entry
      so that the user can understand better the nature of the logged command.
      590d55a2
  6. 13 Apr, 2012 2 commits
    • antirez's avatar
      Stop access to global vars. Not configurable. · 97cab309
      antirez authored
      After considering the interaction between ability to delcare globals in
      scripts using the 'global' function, and the complexities related to
      hanlding replication and AOF in a sane way with globals AND ability to
      turn protection On and Off, we reconsidered the design. The new design
      makes clear that there is only one good way to write Redis scripts, that
      is not using globals. In the rare cases state must be retained across
      calls a Redis key can be used.
      97cab309
    • antirez's avatar
      3e6a4463
  7. 10 Apr, 2012 2 commits
  8. 08 Apr, 2012 1 commit
  9. 05 Apr, 2012 1 commit
  10. 02 Apr, 2012 1 commit
  11. 31 Mar, 2012 1 commit
  12. 30 Mar, 2012 1 commit
  13. 29 Mar, 2012 1 commit
  14. 28 Mar, 2012 2 commits
  15. 27 Mar, 2012 1 commit
  16. 25 Mar, 2012 1 commit
    • antirez's avatar
      New INFO field aof_delayed_fsync introduced. · 81f32c7b
      antirez authored
      This new field counts all the times Redis is configured with AOF enabled and
      fsync policy 'everysec', but the previous fsync performed by the
      background thread was not able to complete within two seconds, forcing
      Redis to perform a write against the AOF file while the fsync is still
      in progress (likely a blocking operation).
      81f32c7b
  17. 22 Mar, 2012 1 commit
    • antirez's avatar
      Support for read-only slaves. Semantical fixes. · 05406168
      antirez authored
      This commit introduces support for read only slaves via redis.conf and CONFIG GET/SET commands. Also various semantical fixes are implemented here:
      
      1) MULTI/EXEC with only read commands now work where the server is into a state where writes (or commands increasing memory usage) are not allowed. Before this patch everything inside a transaction would fail in this conditions.
      
      2) Scripts just calling read-only commands will work against read only
      slaves, when the server is out of memory, or when persistence is into an
      error condition. Before the patch EVAL always failed in this condition.
      05406168
  18. 14 Mar, 2012 1 commit
  19. 13 Mar, 2012 1 commit
  20. 10 Mar, 2012 1 commit
  21. 08 Mar, 2012 3 commits
    • antirez's avatar
      Instantaneous ops/sec figure in INFO output. · 250e7f69
      antirez authored
      250e7f69
    • antirez's avatar
      run_id added to INFO output. · 91d664d6
      antirez authored
      The Run ID is a field that identifies a single execution of the Redis
      server. It can be useful for many purposes as it makes easy to detect if
      the instance we are talking about is the same, or if it is a different
      one or was rebooted. An application of run_id will be in the partial
      synchronization of replication, where a slave may request a partial sync
      from a given offset only if it is talking with the same master. Another
      application is in failover and monitoring scripts.
      91d664d6
    • antirez's avatar
      clusterGetRandomName() generalized into getRandomHexChars() so that we can use... · 44f508f1
      antirez authored
      clusterGetRandomName() generalized into getRandomHexChars() so that we can use it for the run_id field as well.
      44f508f1
  22. 07 Mar, 2012 4 commits
  23. 29 Feb, 2012 1 commit
  24. 28 Feb, 2012 4 commits
  25. 06 Feb, 2012 1 commit
  26. 04 Feb, 2012 2 commits
    • antirez's avatar
      This fixes issue #327, is a very complex fix (unfortunately), details: · f6b32c14
      antirez authored
      1) sendReplyToClient() now no longer stops transferring data to a single
      client in the case we are out of memory (maxmemory-wise).
      
      2) in processCommand() the idea of we being out of memory is no longer
      the naive zmalloc_used_memory() > server.maxmemory. To say if we can
      accept or not write queries is up to the return value of
      freeMemoryIfNeeded(), that has full control about that.
      
      3) freeMemoryIfNeeded() now does its math without considering output
      buffers size. But at the same time it can't let the output buffers to
      put us too much outside the max memory limit, so at the same time it
      makes sure there is enough effort into delivering the output buffers to
      the slaves, calling the write handler directly.
      
      This three changes are the result of many tests, I found (partially
      empirically) that is the best way to address the problem, but maybe
      we'll find better solutions in the future.
      f6b32c14
    • antirez's avatar
      Use less memory when emitting the protocol, by using more shared objects for... · 355f8591
      antirez authored
      Use less memory when emitting the protocol, by using more shared objects for commonly emitted parts of the protocol.
      355f8591
  27. 02 Feb, 2012 1 commit