MEMORY MALLOC-STATS

Introduction and Use Case(s)

MEMORY MALLOC-STATS is a debugging command in Redis used to display internal statistics from the memory allocator. This command provides detailed information about memory usage patterns, which can be invaluable for diagnosing memory fragmentation issues and optimizing memory usage in Redis instances.

Syntax

  1. MEMORY MALLOC-STATS

Parameter Explanations

MEMORY MALLOC-STATS does not take any parameters.

Return Values

The command returns a bulk string with details about the memory allocator’s internal state. The output is typically extensive and includes various metrics related to memory allocation and usage.

Example Output

  1. ___ Begin jemalloc statistics ___
  2. Version: 5.1.0-0-g4e8a9e104889e7e0906cde300e2b313dd843d1e7
  3. Assertions enabled
  4. Run-time option settings:
  5.   opt.abort: false
  6.   opt.lg_chunk: 21
  7. ...
  8. Allocated: 8388608, active: 9437184, metadata: 118784, resident: 9961472, mapped: 100663296, retained: 0
  9. ___ End jemalloc statistics ___

Code Examples

  1. dragonfly> MEMORY MALLOC-STATS
  2. "___ Begin jemalloc statistics ___\nVersion: 5.1.0-0-g4e8a9e104889e7e0906cde300e2b313dd843d1e7\nAssertions enabled\nRun-time option settings:\n  opt.abort: false\n  opt.lg_chunk: 21\n...\nAllocated: 8388608, active: 9437184, metadata: 118784, resident: 9961472, mapped: 100663296, retained: 0\n___ End jemalloc statistics ___"

Best Practices

  • Use MEMORY MALLOC-STATS primarily in development or staging environments where you can safely analyze and act upon the detailed memory statistics without impacting production stability.
  • Combine this command with other memory-related commands like INFO memory for a comprehensive understanding of your Redis instance’s memory usage.

Common Mistakes

  • Avoid running MEMORY MALLOC-STATS frequently in production as the data returned can be verbose and may slightly affect performance due to the overhead in generating the statistics.

FAQs

What is the main use of MEMORY MALLOC-STATS?

MEMORY MALLOC-STATS is mainly used for debugging purposes to understand how the memory allocator in Redis is managing memory, useful for diagnosing memory fragmentation or leaks.

Can MEMORY MALLOC-STATS be used in all versions of Redis?

No, this command is specific to Redis versions that use the Jemalloc allocator, which is generally the default allocator for Redis.