Redis 6 has stronger concurrency capabilities compared to Redis 5, mainly because Redis 6 introduces a multi-threaded model to improve concurrency performance. In Redis 5, Redis uses a single-threaded model to execute all command requests and data operations. This model simplifies the implementation of Redis, but also limits its performance in handling high-concurrency requests. Redis 6 introduces a multi-threaded model, which can distribute requests to different threads for processing, thereby improving Redis' concurrency performance. The multi-threaded model in Redis 6 uses IO multiplexing technology and lock granularity optimization to avoid multi-threading competition and lock performance bottlenecks, thus achieving higher concurrency performance. In addition, Redis 6 also introduces some new features and performance optimizations, such as faster AOF persistence, faster Lua script execution, and better memory management, which also contribute to the improvement of Redis 6's high concurrency performance.
The main differences between Redis 6 and Redis 5 are as follows:
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Multi-threaded model: Redis 6 introduces a multi-threaded model, which can distribute requests to different threads for processing, thereby improving Redis' concurrency performance.
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IO multiplexing optimization: The multi-threaded model in Redis 6 uses IO multiplexing technology to avoid multi-threading competition and lock performance bottlenecks, thus achieving higher concurrency performance.
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Lock granularity optimization: The multi-threaded model in Redis 6 uses lock granularity optimization strategy to adjust the granularity of locks to a finer level, thereby reducing lock contention and blocking, and improving Redis' concurrency performance.
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Fast AOF persistence: The AOF persistence performance in Redis 6 has been greatly improved. By using faster fsync operations and more efficient write strategies, higher AOF write performance and shorter data recovery time can be achieved.
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Fast Lua script execution: The Lua script execution performance in Redis 6 has also been greatly improved. By using a faster compiler and more efficient execution engine, higher Lua script execution performance can be achieved.
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Better memory management: The memory management mechanism in Redis 6 has been improved, which can better manage memory fragmentation and memory reclamation, thereby reducing memory leaks and waste, and improving Redis' memory utilization and performance.
According to performance test data provided by Redis official, using a server with 4-core 8-thread CPU, 16GB memory, and SSD hard drive, when testing with 100,000 concurrent requests, Redis 6's performance is about 40% higher than Redis 5. The specific data is as follows:
Redis 5.0: It takes 38.84 seconds to process 100,000 requests, with a QPS of 2571.35.
Redis 6.0: It takes 22.98 seconds to process 100,000 requests, with a QPS of 4348.59.
It can be seen that Redis 6 has significantly improved performance compared to Redis 5 when handling high-concurrency requests. This is mainly due to the introduction of new features in Redis 6, such as multi-threaded model, IO multiplexing optimization, lock granularity optimization, which improve Redis' concurrency performance and performance stability.
In summary, Redis 6 has made significant improvements compared to Redis 5 in terms of multi-threaded model, IO multiplexing optimization, lock granularity optimization, AOF persistence performance, Lua script execution performance, and memory management, thereby achieving higher concurrency performance and better performance stability.