1. 10 Jul, 2023 4 commits
  2. 07 Jul, 2023 1 commit
    • Binbin's avatar
      Initialize cluster owner_not_claiming_slot to avoid warning (#12391) · 14f802b3
      Binbin authored
      valgrind report a Uninitialised warning:
      ```
      ==25508==  Uninitialised value was created by a heap allocation
      ==25508==    at 0x4848899: malloc (in
      /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
      ==25508==    by 0x1A35A1: ztrymalloc_usable_internal (zmalloc.c:117)
      ==25508==    by 0x1A368D: zmalloc (zmalloc.c:145)
      ==25508==    by 0x21FDEA: clusterInit (cluster.c:973)
      ==25508==    by 0x19DC09: main (server.c:7306)
      ```
      
      Introduced in #12344
      14f802b3
  3. 06 Jul, 2023 2 commits
    • zhaozhao.zz's avatar
      add an assertion to make sure numkeys is 0 in getKeysUsingKeySpecs (#12389) · aefdc57f
      zhaozhao.zz authored
      This is an addition to #12380, to prevent potential bugs when collecting
      keys from multiple commands in the future.
      Note that this function also resets numkeys in some cases.
      aefdc57f
    • Sankar's avatar
      Process loss of slot ownership in cluster bus (#12344) · 1190f25c
      Sankar authored
      Process loss of slot ownership in cluster bus
      
      When a node no longer owns a slot, it clears the bit corresponding
      to the slot in the cluster bus messages. The receiving nodes
      currently don't record the fact that the sender stopped claiming
      a slot until some other node in the cluster starts claiming the slot.
      This can cause a slot to go missing during slot migration when subjected
      to inopportune race with addition of new shards or a failover.
      This fix forces the receiving nodes to process the loss of ownership
      to avoid spreading wrong information.
      1190f25c
  4. 05 Jul, 2023 2 commits
    • Job Henandez Lara's avatar
      redis-benchmark: add documentation for the amount of clients needed (#12372) · b35e20d1
      Job Henandez Lara authored
      In cluster mode, we need more clients than the number of nodes.
      b35e20d1
    • Binbin's avatar
      Fix and increase tollerance of event loop test, add verbose logs (#12385) · d56a7d9b
      Binbin authored
      The test fails on freebsd CI:
      ```
      *** [err]: stats: eventloop metrics in tests/unit/info.tcl
      Expected '31777' to be less than '16183' (context: type eval line 17 cmd
      {assert_lessthan $el_sum2 [expr $el_sum1+10000] } proc ::test)
      ```
      
      The test added in #11963, fails on freebsd CI which is slow,
      increase tollerance and also add some verbose logs, now we can
      see these logs in verbose mode (for better views):
      ```
      eventloop metrics cycle1: 12, cycle2: 15
      eventloop metrics el_sum1: 315, el_sum2: 411
      eventloop metrics cmd_sum1: 126, cmd_sum2: 137
      [ok]: stats: eventloop metrics (111 ms)
      instantaneous metrics instantaneous_eventloop_cycles_per_sec: 8
      instantaneous metrics instantaneous_eventloop_duration_usec: 55
      [ok]: stats: instantaneous metrics (1603 ms)
      [ok]: stats: debug metrics (112 ms)
      ```
      d56a7d9b
  5. 03 Jul, 2023 1 commit
    • Lior Lahav's avatar
      Fix possible crash in command getkeys (#12380) · b7559d9f
      Lior Lahav authored
      
      
      When getKeysUsingKeySpecs processes a command with more than one key-spec,
      and called with a total of more than 256 keys, it'll call getKeysPrepareResult again,
      but since numkeys isn't updated, getKeysPrepareResult will not bother to copy key
      names from the old result (leaving these slots uninitialized). Furthermore, it did not
      consider the keys it already found when allocating more space.
      Co-authored-by: default avatarOran Agra <oran@redislabs.com>
      b7559d9f
  6. 02 Jul, 2023 1 commit
  7. 01 Jul, 2023 1 commit
  8. 29 Jun, 2023 1 commit
  9. 27 Jun, 2023 5 commits
  10. 26 Jun, 2023 1 commit
    • Chen Tianjie's avatar
      Support TLS service when "tls-cluster" is not enabled and persist both plain... · 22a29935
      Chen Tianjie authored
      Support TLS service when "tls-cluster" is not enabled and persist both plain and TLS port in nodes.conf (#12233)
      
      Originally, when "tls-cluster" is enabled, `port` is set to TLS port. In order to support non-TLS clients, `pport` is used to propagate TCP port across cluster nodes. However when "tls-cluster" is disabled, `port` is set to TCP port, and `pport` is not used, which means the cluster cannot provide TLS service unless "tls-cluster" is on.
      ```
      typedef struct {
          // ...
          uint16_t port;  /* Latest known clients port (TLS or plain). */
          uint16_t pport; /* Latest known clients plaintext port. Only used if the main clients port is for TLS. */
          // ...
      } clusterNode;
      ```
      ```
      typedef struct {
          // ...
          uint16_t port;   /* TCP base port number. */
          uint16_t pport;  /* Sender TCP plaintext port, if base port is TLS */
          // ...
      } clusterMsg;
      ```
      This PR renames `port` and `pport` in `clusterNode` to `tcp_port` and `tls_port`, to record both ports no matter "tls-cluster" is enabled or disabled.
      
      This allows to provide TLS service to clients when "tls-cluster" is disabled: when displaying cluster topology, or giving `MOVED` error, server can provide TLS or TCP port according to client's connection type, no matter what type of connection cluster bus is using.
      
      For backwards compatibility, `port` and `pport` in `clusterMsg` are preserved, when "tls-cluster" is enabled, `port` is set to TLS port and `pport` is set to TCP port, when "tls-cluster" is disabled, `port` is set to TCP port and `pport` is set to TLS port (instead of 0).
      
      Also, in the nodes.conf file, a new aux field displaying an extra port is added to complete the persisted info. We may have `tls_port=xxxxx` or `tcp_port=xxxxx` in the aux field, to complete the cluster topology, while the other port is stored in the normal `<ip>:<port>` field. The format is shown below.
      ```
      <node-id> <ip>:<tcp_port>@<cport>,<hostname>,shard-id=...,tls-port=6379 myself,master - 0 0 0 connected 0-1000
      ```
      Or we can switch the position of two ports, both can be correctly resolved.
      ```
      <node-id> <ip>:<tls_port>@<cport>,<hostname>,shard-id=...,tcp-port=6379 myself,master - 0 0 0 connected 0-1000
      ```
      22a29935
  11. 25 Jun, 2023 2 commits
    • Binbin's avatar
      Move clusterBeforeSleep before blockedBeforeSleep (#12343) · 9600553e
      Binbin authored
      The new blockedBeforeSleep was added in #12337, it breaks the order in 2ecb5edf.
      
      This may be related to #2288, quoted from comment in #2288:
      ```
      Moreover the clusterBeforeSleep() call was misplaced at the end of the chain of the
      beforeSleep() call in redis.c. It should be at the top, before processing un blocking
      clients. This is exactly the reason in the specific instance of the bug as reported,
      why the state was not updated in time before clients served.
      ```
      9600553e
    • Meir Shpilraien (Spielrein)'s avatar
      Fix use after free on blocking RM_Call. (#12342) · 153f8f08
      Meir Shpilraien (Spielrein) authored
      blocking RM_Call was introduced on: #11568, It allows a module to perform
      blocking commands and get the reply asynchronously.If the command gets
      block, a special promise CallReply is returned that allow to set the unblock
      handler. The unblock handler will be called when the command invocation
      finish and it gets, as input, the command real reply.
      
      The issue was that the real CallReply was created using a stack allocated
      RedisModuleCtx which is no longer available after the unblock handler finishes.
      So if the module keeps the CallReply after the unblock handler finished, the
      CallReply holds a pointer to invalid memory and will try to access it when the
      CallReply will be released.
      
      The solution is to create the CallReply with a NULL context to make it totally
      detached and can be freed freely when the module wants.
      
      Test was added to cover this case, running the test with valgrind before the
      fix shows the use after free error. With the fix, there are no valgrind errors.
      
      unrelated: adding a missing `$rd close` in many tests in that file.
      153f8f08
  12. 22 Jun, 2023 2 commits
    • guybe7's avatar
      Modules: Unblock from within a timer coverage (#12337) · 32301999
      guybe7 authored
      Apart from adding the missing coverage, this PR also adds `blockedBeforeSleep`
      that gathers all block-related functions from `beforeSleep`
      
      The order inside `blockedBeforeSleep` is different: now `handleClientsBlockedOnKeys`
      (which may unblock clients) is called before `processUnblockedClients` (which handles
      unblocked clients).
      It makes sense to have this order.
      
      There are no visible effects of the wrong ordering, except some cleanups of the now-unblocked
      client would have  happen in the next `beforeSleep` (will now happen in the current one)
      
      The reason we even got into it is because i triggers an assertion in logresreq.c (breaking
      the assumption that `unblockClient` is called **before** actually flushing the reply to the socket):
      `handleClientsBlockedOnKeys` is called, then it calls `moduleUnblockClientOnKey`, which calls
      `moduleUnblockClient`, which adds the client to `moduleUnblockedClients` back to `beforeSleep`,
      we call `handleClientsWithPendingWritesUsingThreads`, it writes the data of buf to the client, so
      `client->bufpos` became 0
      On the next `beforeSleep`, we call `moduleHandleBlockedClients`, which calls `unblockClient`,
      which calls `reqresAppendResponse`, triggering the assert. (because the `bufpos` is 0) - see https://github.com/redis/redis/pull/12301#discussion_r1226386716
      32301999
    • Gabi Ganam's avatar
      Fix typos in comments (#12338) · 9e5f45f2
      Gabi Ganam authored
      9e5f45f2
  13. 21 Jun, 2023 3 commits
    • Binbin's avatar
      Print strerror when bio initialization fails (#12333) · 47f32bc9
      Binbin authored
      Now we can see something like this:
      ```
      Fatal: Can't initialize Background Jobs. Error message: Cannot allocate memory
      ```
      47f32bc9
    • guybe7's avatar
      Improve moduleBlockClient timeout overflow handling (#12174) · d46ef886
      guybe7 authored
      Continuation of https://github.com/redis/redis/pull/11338
      avoid overflow adding input timeout to "now" in moduleBlockClient.
      d46ef886
    • Madelyn Olson's avatar
      Make nodename test more consistent (#12330) · 73cf0243
      Madelyn Olson authored
      To determine when everything was stable, we couldn't just query the nodename since they aren't API visible by design. Instead, we were using a proxy piece of information which was bumping the epoch and waiting for everyone to observe that. This works for making source Node 0 and Node 1 had pinged, and Node 0 and Node 2 had pinged, but did not guarantee that Node 1 and Node 2 had pinged. Although unlikely, this can cause this failure message. To fix it I hijacked hostnames and used its validation that it has been propagated, since we know that it is stable.
      
      I also noticed while stress testing this sometimes the test took almost 4.5 seconds to finish, which is really close to the current 5 second limit of the log check, so I bumped that up as well just to make it a bit more consistent.
      73cf0243
  14. 20 Jun, 2023 10 commits
    • guybe7's avatar
      Align RM_ReplyWithErrorFormat with RM_ReplyWithError (#12321) · 20fa1560
      guybe7 authored
      Introduced by https://github.com/redis/redis/pull/11923 (Redis 7.2 RC2)
      
      It's very weird and counterintuitive that `RM_ReplyWithError` requires the error-code
      **without** a hyphen while `RM_ReplyWithErrorFormat` requires either the error-code
      **with** a hyphen or no error-code at all
      ```
      RedisModule_ReplyWithError(ctx, "BLA bla bla");
      ```
      vs.
      ```
      RedisModule_ReplyWithErrorFormat(ctx, "-BLA %s", "bla bla");
      ```
      
      This commit aligns RM_ReplyWithErrorFormat to behvae like RM_ReplyWithError.
      it's a breaking changes but it's done before 7.2 goes GA.
      20fa1560
    • Oran Agra's avatar
      Fix broken protocol when PUBLISH emits local push inside MULTI (#12326) · 8ad8f0f9
      Oran Agra authored
      When a connection that's subscribe to a channel emits PUBLISH inside MULTI-EXEC,
      the push notification messes up the EXEC response.
      
      e.g. MULTI, PING, PUSH foo bar, PING, EXEC
      the EXEC's response will contain: PONG, {message foo bar}, 1. and the second PONG
      will be delivered outside the EXEC's response.
      
      Additionally, this PR changes the order of responses in case of a plain PUBLISH (when
      the current client also subscribed to it), by delivering the push after the command's
      response instead of before it.
      This also affects modules calling RM_PublishMessage in a similar way, so that we don't
      run the risk of getting that push mixed together with the module command's response.
      8ad8f0f9
    • judeng's avatar
      use embedded string object and more efficient ll2string for long long value... · 93708c7f
      judeng authored
      
      use embedded string object and more efficient ll2string for long long value convert to string (#12250)
      
      A value of type long long is always less than 21 bytes when convert to a
      string, so always meets the conditions for using embedded string object
      which can always get memory reduction and performance gain (less calls
      to the heap allocator).
      Additionally, for the conversion of longlong type to sds, we also use a faster
      algorithm (the one in util.c instead of the one that used to be in sds.c). 
      
      For the DECR command on 32-bit Redis, we get about a 5.7% performance
      improvement. There will also be some performance gains for some commands
      that heavily use sdscatfmt to convert numbers, such as INFO.
      Co-authored-by: default avatarOran Agra <oran@redislabs.com>
      93708c7f
    • Binbin's avatar
      zrangeGenericCommand add check for negative offset (#9052) · d9c2ef8a
      Binbin authored
      Now we will check the offset in zrangeGenericCommand.
      With a negative offset, we will throw an error and return.
      
      This also resolve the issue of zeroing the destination key
      in case of the "store" variant when we input a negative offset.
      ```
      127.0.0.1:6379> set key value
      OK
      127.0.0.1:6379> zrangestore key myzset 0 10 byscore limit -1 10
      (integer) 0
      127.0.0.1:6379> exists key
      (integer) 0
      ```
      
      This change affects the following commands:
      - ZRANGE / ZRANGESTORE / ZRANGEBYLEX / ZRANGEBYSCORE
      - ZREVRANGE / ZREVRANGEBYSCORE / ZREVRANGEBYLEX
      d9c2ef8a
    • Wen Hui's avatar
      adding geo command edge cases tests (#12274) · 66ea178c
      Wen Hui authored
      For geosearch and georadius we have already test coverage for wrong type, but we dont have for geodist, geohash, geopos commands. So adding the wrong type test cases for geodist, geohash, geopos commands.
      
      Existing code, we have verify_geo_edge_response_bymember function for wrong type test cases which has member as an option. But the function is being called in other test cases where the output is not inline with these commnds(geodist, geohash, geopos). So I could not include these commands(geodist, geohash, geopos) as part of existing function, hence implemented a new function verify_geo_edge_response_generic and called from the test case.
      66ea178c
    • Binbin's avatar
      Fix ZRANK/ZREVRANK reply_schema description (#12331) · d306d861
      Binbin authored
      The parameter name is WITHSCORE instead of WITHSCORES.
      d306d861
    • mstmdev's avatar
      13e17e94
    • Wen Hui's avatar
      Sanitizer reported memory leak for '--invalid' option or port number is missed... · 813924b4
      Wen Hui authored
      
      Sanitizer reported memory leak for '--invalid' option or port number is missed cases to redis-server. (#12322)
      
      Observed that the sanitizer reported memory leak as clean up is not done
      before the process termination in negative/following cases:
      
      **- when we passed '--invalid' as option to redis-server.**
      
      ```
       -vm:~/mem-leak-issue/redis$ ./src/redis-server --invalid
      
      *** FATAL CONFIG FILE ERROR (Redis 255.255.255) ***
      Reading the configuration file, at line 2
      >>> 'invalid'
      Bad directive or wrong number of arguments
      
      =================================================================
      ==865778==ERROR: LeakSanitizer: detected memory leaks
      
      Direct leak of 8 byte(s) in 1 object(s) allocated from:
          #0 0x7f0985f65867 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145
          #1 0x558ec86686ec in ztrymalloc_usable_internal /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:117
          #2 0x558ec86686ec in ztrymalloc_usable /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:135
          #3 0x558ec86686ec in ztryrealloc_usable_internal /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:276
          #4 0x558ec86686ec in zrealloc /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:327
          #5 0x558ec865dd7e in sdssplitargs /home/ubuntu/mem-leak-issue/redis/src/sds.c:1172
          #6 0x558ec87a1be7 in loadServerConfigFromString /home/ubuntu/mem-leak-issue/redis/src/config.c:472
          #7 0x558ec87a13b3 in loadServerConfig /home/ubuntu/mem-leak-issue/redis/src/config.c:718
          #8 0x558ec85e6f15 in main /home/ubuntu/mem-leak-issue/redis/src/server.c:7258
          #9 0x7f09856e5d8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      
      SUMMARY: AddressSanitizer: 8 byte(s) leaked in 1 allocation(s).
      
      ```
      
      **- when we pass '--port' as option and missed to add port number to redis-server.**
      
      ```
      vm:~/mem-leak-issue/redis$ ./src/redis-server --port
      
      *** FATAL CONFIG FILE ERROR (Redis 255.255.255) ***
      Reading the configuration file, at line 2
      >>> 'port'
      wrong number of arguments
      
      =================================================================
      ==865846==ERROR: LeakSanitizer: detected memory leaks
      
      Direct leak of 8 byte(s) in 1 object(s) allocated from:
          #0 0x7fdcdbb1f867 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145
          #1 0x557e8b04f6ec in ztrymalloc_usable_internal /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:117
          #2 0x557e8b04f6ec in ztrymalloc_usable /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:135
          #3 0x557e8b04f6ec in ztryrealloc_usable_internal /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:276
          #4 0x557e8b04f6ec in zrealloc /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:327
          #5 0x557e8b044d7e in sdssplitargs /home/ubuntu/mem-leak-issue/redis/src/sds.c:1172
          #6 0x557e8b188be7 in loadServerConfigFromString /home/ubuntu/mem-leak-issue/redis/src/config.c:472
          #7 0x557e8b1883b3 in loadServerConfig /home/ubuntu/mem-leak-issue/redis/src/config.c:718
          #8 0x557e8afcdf15 in main /home/ubuntu/mem-leak-issue/redis/src/server.c:7258
          #9 0x7fdcdb29fd8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      
      Indirect leak of 10 byte(s) in 1 object(s) allocated from:
          #0 0x7fdcdbb1fc18 in __interceptor_realloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:164
          #1 0x557e8b04f9aa in ztryrealloc_usable_internal /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:287
          #2 0x557e8b04f9aa in ztryrealloc_usable /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:317
          #3 0x557e8b04f9aa in zrealloc_usable /home/ubuntu/mem-leak-issue/redis/src/zmalloc.c:342
          #4 0x557e8b033f90 in _sdsMakeRoomFor /home/ubuntu/mem-leak-issue/redis/src/sds.c:271
          #5 0x557e8b033f90 in sdsMakeRoomFor /home/ubuntu/mem-leak-issue/redis/src/sds.c:295
          #6 0x557e8b033f90 in sdscatlen /home/ubuntu/mem-leak-issue/redis/src/sds.c:486
          #7 0x557e8b044e1f in sdssplitargs /home/ubuntu/mem-leak-issue/redis/src/sds.c:1165
          #8 0x557e8b188be7 in loadServerConfigFromString /home/ubuntu/mem-leak-issue/redis/src/config.c:472
          #9 0x557e8b1883b3 in loadServerConfig /home/ubuntu/mem-leak-issue/redis/src/config.c:718
          #10 0x557e8afcdf15 in main /home/ubuntu/mem-leak-issue/redis/src/server.c:7258
          #11 0x7fdcdb29fd8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      
      SUMMARY: AddressSanitizer: 18 byte(s) leaked in 2 allocation(s).
      
      ```
      
      As part analysis found that the sdsfreesplitres is not called when this condition checks are being hit.
      
      Output after the fix:
      
      
      ```
      vm:~/mem-leak-issue/redis$ ./src/redis-server --invalid
      
      *** FATAL CONFIG FILE ERROR (Redis 255.255.255) ***
      Reading the configuration file, at line 2
      >>> 'invalid'
      Bad directive or wrong number of arguments
      vm:~/mem-leak-issue/redis$
      
      ===========================================
      vm:~/mem-leak-issue/redis$ ./src/redis-server --jdhg
      
      *** FATAL CONFIG FILE ERROR (Redis 255.255.255) ***
      Reading the configuration file, at line 2
      >>> 'jdhg'
      Bad directive or wrong number of arguments
      
      ---------------------------------------------------------------------------
      vm:~/mem-leak-issue/redis$ ./src/redis-server --port
      
      *** FATAL CONFIG FILE ERROR (Redis 255.255.255) ***
      Reading the configuration file, at line 2
      >>> 'port'
      wrong number of arguments
      ```
      Co-authored-by: default avatarOran Agra <oran@redislabs.com>
      813924b4
    • Shaya Potter's avatar
      Add ability for modules to know which client is being cmd filtered (#12219) · 07316f16
      Shaya Potter authored
      Adds API
      - RedisModule_CommandFilterGetClientId()
      
      Includes addition to commandfilter test module to validate that it works
      by performing the same command from 2 different clients
      07316f16
    • Binbin's avatar
      Fix cluster human_nodename Getter data loss in nodes.conf (#12325) · cd4f3e20
      Binbin authored
      auxHumanNodenameGetter limited to %.40s, since we did not limit the
      length of config cluster-announce-human-nodename, %.40s will cause
      nodename data loss (we will persist it in nodes.conf).
      
      Additional modified auxHumanNodenamePresent to use sdslen.
      cd4f3e20
  15. 19 Jun, 2023 1 commit
    • Binbin's avatar
      Optimize PSUBSCRIBE and PUNSUBSCRIBE from O(N*M) to O(N) (#12298) · b5106249
      Binbin authored
      In the original implementation, the time complexity of the commands
      is actually O(N*M), where N is the number of patterns the client is
      already subscribed and M is the number of patterns to subscribe to.
      The docs are all wrong about this.
      
      Specifically, because the original client->pubsub_patterns is a list,
      so we need to do listSearchKey which is O(N). In this PR, we change it
      to a dict, so the search becomes O(1).
      
      At the same time, both pubsub_channels and pubsubshard_channels are dicts.
      Changing pubsub_patterns to a dictionary improves the readability and
      maintainability of the code.
      b5106249
  16. 18 Jun, 2023 2 commits
    • Oran Agra's avatar
      Set Jemalloc --disable-cache-oblivious to reduce memory overhead (#12315) · 07c14672
      Oran Agra authored
      Apparently for large size classes Jemalloc allocate some extra
      memory (can be up to 25% overhead for allocations of 16kb).
      see https://github.com/jemalloc/jemalloc/issues/1098#issuecomment-1589870476
      
      p.s. from Redis's perspective that looks like external fragmentation,
      (i.e. allocated bytes will be low, and active pages bytes will be large)
      which  can cause active-defrag to eat CPU cycles in vain.
      
      Some details about this mechanism we disable:
      ---------------------------------------------------------------
      Disabling this mechanism only affects large allocations (above 16kb)
      Not only that it isn't expected to cause any performance regressions,
      it's actually recommended, unless you have a specific workload pattern
      and hardware that benefit from this feature -- by default it's enabled and
      adds address randomization to all large buffers, by over allocating 1 page
      per large size class, and offsetting into that page to make the starting
      address of the user buffer randomized. Workloads such as scientific
      computation often handle multiple big matrixes at the same time, and the
      randomization makes sure that the cacheline level accesses don't suffer
      bad conflicts (when they all start from page-aligned addresses).
      
      However the downsize is also quite noticeable, like you observed that extra
      page per large size can cause memory overhead, plus the extra TLB entry.
      The other factor is, hardware in the last few years started doing the
      randomization at the hardware level, i.e. the address to cacheline mapping isn't
      a direct mapping anymore. So there's debate to disable the randomization by default,
      but we are still hesitant because when it matters, it could matter a lot, and having
      it enabled by default limits that worst case behavior, even though it means the
      majority of workloads suffers a regression.
      
      So in short, it's safe and offers better performance in most cases.
      07c14672
    • Wen Hui's avatar
      Cluster human readable nodename feature (#9564) · 070453ee
      Wen Hui authored
      
      
      This PR adds a human readable name to a node in clusters that are visible as part of error logs. This is useful so that admins and operators of Redis cluster have better visibility into failures without having to cross-reference the generated ID with some logical identifier (such as pod-ID or EC2 instance ID). This is mentioned in #8948. Specific nodenames can be set by using the variable cluster-announce-human-nodename. The nodename is gossiped using the clusterbus extension in #9530.
      Co-authored-by: default avatarMadelyn Olson <madelyneolson@gmail.com>
      070453ee
  17. 16 Jun, 2023 1 commit
    • sundb's avatar
      Use Reservoir Sampling for random sampling of dict, and fix hang during fork (#12276) · b00a2351
      sundb authored
      
      
      ## Issue:
      When a dict has a long chain or the length of the chain is longer than
      the number of samples, we will never be able to sample the elements
      at the end of the chain using dictGetSomeKeys().
      This could mean that SRANDMEMBER can be hang in and endless loop.
      The most severe case, is the pathological case of when someone uses SCAN+DEL
      or SSCAN+SREM creating an unevenly distributed dict.
      This was amplified by the recent change in #11692 which prevented a
      down-sizing rehashing while there is a fork.
      
      ## Solution
      1. Before, we will stop sampling when we reach the maximum number
        of samples, even if there is more data after the current chain.
        Now when we reach the maximum we use the Reservoir Sampling
        algorithm to fairly sample the end of the chain that cannot be sampled
      2. Fix the rehashing code, so that the same as it allows rehashing for up-sizing
        during fork when the ratio is extreme, it will allow it for down-sizing as well.
      
      Issue was introduced (or became more severe) by #11692
      Co-authored-by: default avatarOran Agra <oran@redislabs.com>
      b00a2351