- 09 Mar, 2022 1 commit
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Oran Agra authored
* stats and latency commands have non-deterministic output. * the ones about latency should be sent to ALL_NODES (considering reads from replicas) * the ones about running scripts and memory usage only to masters. * stats aggregation is SPECIAL (like in INFO)
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- 05 Jan, 2022 1 commit
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filipe oliveira authored
Added INFO LATENCYSTATS section: latency by percentile distribution/latency by cumulative distribution of latencies (#9462) # Short description The Redis extended latency stats track per command latencies and enables: - exporting the per-command percentile distribution via the `INFO LATENCYSTATS` command. **( percentile distribution is not mergeable between cluster nodes ).** - exporting the per-command cumulative latency distributions via the `LATENCY HISTOGRAM` command. Using the cumulative distribution of latencies we can merge several stats from different cluster nodes to calculate aggregate metrics . By default, the extended latency monitoring is enabled since the overhead of keeping track of the command latency is very small. If you don't want to track extended latency metrics, you can easily disable it at runtime using the command: - `CONFIG SET latency-tracking no` By default, the exported latency percentiles are the p50, p99, and p999. You can alter them at runtime using the command: - `CONFIG SET latency-tracking-info-percentiles "0.0 50.0 100.0"` ## Some details: - The total size per histogram should sit around 40 KiB. We only allocate those 40KiB when a command was called for the first time. - With regards to the WRITE overhead As seen below, there is no measurable overhead on the achievable ops/sec or full latency spectrum on the client. Including also the measured redis-benchmark for unstable vs this branch. - We track from 1 nanosecond to 1 second ( everything above 1 second is considered +Inf ) ## `INFO LATENCYSTATS` exposition format - Format: `latency_percentiles_usec_<CMDNAME>:p0=XX,p50....` ## `LATENCY HISTOGRAM [command ...]` exposition format Return a cumulative distribution of latencies in the format of a histogram for the specified command names. The histogram is composed of a map of time buckets: - Each representing a latency range, between 1 nanosecond and roughly 1 second. - Each bucket covers twice the previous bucket's range. - Empty buckets are not printed. - Everything above 1 sec is considered +Inf. - At max there will be log2(1000000000)=30 buckets We reply a map for each command in the format: `<command name> : { `calls`: <total command calls> , `histogram` : { <bucket 1> : latency , < bucket 2> : latency, ... } }` Co-authored-by:
Oran Agra <oran@redislabs.com>
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- 15 Dec, 2021 1 commit
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guybe7 authored
Delete the hardcoded command table and replace it with an auto-generated table, based on a JSON file that describes the commands (each command must have a JSON file). These JSON files are the SSOT of everything there is to know about Redis commands, and it is reflected fully in COMMAND INFO. These JSON files are used to generate commands.c (using a python script), which is then committed to the repo and compiled. The purpose is: * Clients and proxies will be able to get much more info from redis, instead of relying on hard coded logic. * drop the dependency between Redis-user and the commands.json in redis-doc. * delete help.h and have redis-cli learn everything it needs to know just by issuing COMMAND (will be done in a separate PR) * redis.io should stop using commands.json and learn everything from Redis (ultimately one of the release artifacts should be a large JSON, containing all the information about all of the commands, which will be generated from COMMAND's reply) * the byproduct of this is: * module commands will be able to provide that info and possibly be more of a first-class citizens * in theory, one may be able to generate a redis client library for a strictly typed language, by using this info. ### Interface changes #### COMMAND INFO's reply change (and arg-less COMMAND) Before this commit the reply at index 7 contained the key-specs list and reply at index 8 contained the sub-commands list (Both unreleased). Now, reply at index 7 is a map of: - summary - short command description - since - debut version - group - command group - complexity - complexity string - doc-flags - flags used for documentation (e.g. "deprecated") - deprecated-since - if deprecated, from which version? - replaced-by - if deprecated, which command replaced it? - history - a list of (version, what-changed) tuples - hints - a list of strings, meant to provide hints for clients/proxies. see https://github.com/redis/redis/issues/9876 - arguments - an array of arguments. each element is a map, with the possibility of nesting (sub-arguments) - key-specs - an array of keys specs (already in unstable, just changed location) - subcommands - a list of sub-commands (already in unstable, just changed location) - reply-schema - will be added in the future (see https://github.com/redis/redis/issues/9845) more details on these can be found in https://github.com/redis/redis-doc/pull/1697 only the first three fields are mandatory #### API changes (unreleased API obviously) now they take RedisModuleCommand opaque pointer instead of looking up the command by name - RM_CreateSubcommand - RM_AddCommandKeySpec - RM_SetCommandKeySpecBeginSearchIndex - RM_SetCommandKeySpecBeginSearchKeyword - RM_SetCommandKeySpecFindKeysRange - RM_SetCommandKeySpecFindKeysKeynum Currently, we did not add module API to provide additional information about their commands because we couldn't agree on how the API should look like, see https://github.com/redis/redis/issues/9944 . ### Somehow related changes 1. Literals should be in uppercase while placeholder in lowercase. Now all the GEO* command will be documented with M|KM|FT|MI and can take both lowercase and uppercase ### Unrelated changes 1. Bugfix: no_madaory_keys was absent in COMMAND's reply 2. expose CMD_MODULE as "module" via COMMAND 3. have a dedicated uint64 for ACL categories (instead of having them in the same uint64 as command flags) Co-authored-by:
Itamar Haber <itamar@garantiadata.com>
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