5358bd7cdd
#### Problem Statement: For any read/update operation during rehashing, we're doing ~10+ random DRAM lookups to do the rehashing, as we are using the `rehashidx` to rehash 10 buckets, whose dict entries most likely aren't cached in the CPU or near the bucket we are operating on. If these random bucket are empty, the rehashing process during that command execution is skipped. #### Implementation: For reducing the performance recession while dict is rehashing, we determine the index at which the key would be stored in the 0th HT, we check if that index has already been rehashed, if not we will rehash the bucket containing the key and the bucket will be moved from 0th HT to the 1st HT. If the key has already been rehashed, we perform the random access bucket rehash (using `rehashidx`) and we again verify if rehashing is still ongoing and look up the key in the respective HT. This ensures rehashing is not skipped in any command call and that we rehash a particular bucket or random bucket in each call. #### Changes in this PR: - Added a new method `dictBucketRehash` to perform rehash on a single bucket. - Helper function `moveKeysInBucketOldtoNew` for `dictRehash` and `dictBucketRehash` to move all the keys in a bucket from the old to the new hash HT. - Helper function `verifyMoreRehashRequired` for `dictRehash` and `dictBucketRehash` to check if we have already rehashed the whole table and if more rehashing is required. ### Benchmark: - This PR still shows **~13%** improvement in the latency during rehashing. - Rehashing is now **~2%** faster for this PR when compared to unstable. --------- Co-authored-by: Oran Agra <oran@redislabs.com> Co-authored-by: Madelyn Olson <34459052+madolson@users.noreply.github.com>
Redis Test Suite
The normal execution mode of the test suite involves starting and manipulating
local redis-server instances, inspecting process state, log files, etc.
The test suite also supports execution against an external server, which is
enabled using the --host and --port parameters. When executing against an
external server, tests tagged external:skip are skipped.
There are additional runtime options that can further adjust the test suite to match different external server configurations:
| Option | Impact |
|---|---|
--singledb |
Only use database 0, don't assume others are supported. |
--ignore-encoding |
Skip all checks for specific encoding. |
--ignore-digest |
Skip key value digest validations. |
--cluster-mode |
Run in strict Redis Cluster compatibility mode. |
--large-memory |
Enables tests that consume more than 100mb |
Tags
Tags are applied to tests to classify them according to the subsystem they test, but also to indicate compatibility with different run modes and required capabilities.
Tags can be applied in different context levels:
start_servercontexttagscontext that bundles several tests together- A single test context.
The following compatibility and capability tags are currently used:
| Tag | Indicates |
|---|---|
external:skip |
Not compatible with external servers. |
cluster:skip |
Not compatible with --cluster-mode. |
large-memory |
Test that requires more than 100mb |
tls:skip |
Not compatible with --tls. |
needs:repl |
Uses replication and needs to be able to SYNC from server. |
needs:debug |
Uses the DEBUG command or other debugging focused commands (like OBJECT REFCOUNT). |
needs:pfdebug |
Uses the PFDEBUG command. |
needs:config-maxmemory |
Uses CONFIG SET to manipulate memory limit, eviction policies, etc. |
needs:config-resetstat |
Uses CONFIG RESETSTAT to reset statistics. |
needs:reset |
Uses RESET to reset client connections. |
needs:save |
Uses SAVE or BGSAVE to create an RDB file. |
When using an external server (--host and --port), filtering using the
external:skip tags is done automatically.
When using --cluster-mode, filtering using the cluster:skip tag is done
automatically.
When not using --large-memory, filtering using the largemem:skip tag is done
automatically.
In addition, it is possible to specify additional configuration. For example, to
run tests on a server that does not permit SYNC use:
./runtest --host <host> --port <port> --tags -needs:repl