[Tech Request]: Harden /debug/malloc pprof output for Pyroscope ingestion

[VioletQwQ-0]

Is there an existing issue for the same tech request?

• I have checked the existing issues.

Does this tech request not affect user experience?

• This tech request doesn't affect user experience.

What would you like to be added ?

Harden MatrixOne's custom /debug/malloc pprof output so that it can be ingested reliably by Pyroscope as a custom malloc profile family.

The malloc/off-heap profile should expose heap-style sample types:

• alloc_objects
• alloc_space
• inuse_objects
• inuse_space

It should also emit complete pprof metadata and mapping information expected by profiling backends.

Why is this needed ?

During Pyroscope validation, /debug/malloc could be fetched and parsed by go tool pprof, and Pyroscope could discover malloc profile types. However, agent/backend ingest could still fail with nil pointer dereference when profile metadata or Location.Mapping information was incomplete.

This issue tracks the MatrixOne-side compatibility hardening required for stable off-heap malloc profiling in Pyroscope.

Additional information

Related validation goals:

• /debug/malloc remains readable by go tool pprof
• emitted profiles pass profile.Parse(...) and p.CheckValid()
• every emitted profile.Location has a non-nil mapping
• Pyroscope can query malloc:inuse_space and malloc:alloc_space
• CN/DN malloc series and flamegraph data are queryable
• longer soak / overhead validation is handled separately in mo-auto-test