How deeply does 100 Go Mistakes and How to Avoid Them cover heap profiling?

Explains sampling, four sample types, and how to read direct versus downstream allocations in a call graph.

Heap profiling

As explained in 100 Go Mistakes and How to Avoid Them

A heap profile is sampled data describing heap memory allocation and the current or historical state of heap usage.

A common mistake is to read a heap graph’s total for a function as memory allocated directly by that function. Follow the call chain: the total can include allocations made by functions it calls. section 12.8.1

Heap profiles sample allocations rather than recording every one. The default rate is one sample per 512 KB of heap allocation. Increasing sampling frequency collects more detail but requires more effort. section 12.8.1

Choose a sample type to match the question:

alloc_objects and alloc_space count all objects and bytes allocated. section 12.8.1
inuse_objects and inuse_space count objects and bytes not yet released. section 12.8.1

Trace an allocation total

A decode call accounts for 1,536 KB, or 6.32% of the heap total, but allocates none of it directly. The next decode call allocates 512 KB directly; another method accounts for the remaining 1,024 KB. section 12.8.1

$ go tool pprof -http=:8080 <file>

Download a profile from /debug/pprof/heap/?debug=0, then use this command with the downloaded file to inspect it in the pprof web UI. section 12.8.1

How 100 Go Mistakes and How to Avoid Them covers it

Cover of 100 Go Mistakes and How to Avoid Them

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Related concepts

monitoringused by · Monitoring is the ongoing observation and measurement of a system’s behavior, state, or operational signals to assess its condition and detect changes or problems.
memory leakaddresses · A memory leak is the unintended retention of allocated memory that a program no longer needs, preventing that memory from being reclaimed for reuse.
Node.jsuses · Node.js is an open-source JavaScript runtime built on the V8 engine that executes JavaScript outside web browsers and provides APIs for system and network operations.

This explainer was generated by Manning's knowledge graph from the text of 100 Go Mistakes and How to Avoid Them. The section links point to the parts of the book it draws on.