Module prof 

Sampling heap profiler.

As in jemalloc, a thread takes a sample after a random number of allocated bytes, exponentially distributed around the sample interval, so each allocation is sampled with probability 1 - exp(-size / interval). A sample records the allocation’s stack; counts per stack are scaled by the inverse of that probability, which makes them unbiased estimates of the real totals.

Sampled allocations live in chunks of their own, so a free only needs to look at the chunk header to know whether it frees a sample.

Structs

Sample

A live sampled allocation, with the fixed point weights it added

Enums

DumpError

Why a heap profile could not be dumped

Constants

DEFAULT_INTERVAL

512 KiB, jemalloc’s default (lg_prof_sample:19)

Functions

activate

Starts sampling allocations

deactivate

Stops taking new samples; live samples stay in the profile

dump_pprof

The heap profile in pprof’s protobuf format, uncompressed (pprof reads both plain and gzipped files). Its sample types follow Go’s heap profiles: alloc_objects, alloc_space, inuse_objects and inuse_space, the default.

is_active

Whether allocations are being sampled

sample_interval

The mean number of bytes between samples

set_sample_interval

Sets the mean number of bytes between samples, from 1 byte to 128 TiB; values outside are clamped

write_pprof

Writes the heap profile to path; returns its size in bytes