package memprof-limits

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Memory limits, allocation limits, and thread cancellation

Install

Dune Dependency

gitlab.com Readme Changelog Edit opam file Versions (3)

Authors

G

Guillaume Munch-Maccagnoni <Guillaume.Munch-Maccagnoni@inria.fr>

Maintainers

G

Guillaume Munch-Maccagnoni <Guillaume.Munch-Maccagnoni@inria.fr>

Sources

memprof-limits-v0.2.1.tar.gz

md5=15026b85944ee405fe6784cc9f1575bb

sha512=6ae138bc582911ab221f8c8a4a461b58bfcb837933b989ea9f10ef8cdd54a445c300f41fa4a0ec70746a27c24ccae5598666c98195a8400bc7c5c37e9327480b

doc/memprof-limits/Memprof_limits/Memprof/index.html

Module `Memprof_limits.Memprof`Source

Use this reimplementation of the Memprof interface if you need to profile a program that uses Memprof-limits.

Note: the expectancy (1/sampling_rate) provided in Memprof.start is rounded to the nearest integer for the accuracy of allocation limits accounting.

include module type of Gc.Memprof

Sourcetype allocation_source =

| Normal
| Marshal
| Custom

Sourcetype allocation = private {

n_samples : int;
(*
The number of samples in this block (>= 1).
*)
size : int;
(*
The size of the block, in words, excluding the header.
*)
source : allocation_source;
(*
The type of the allocation.
*)
callstack : Printexc.raw_backtrace;
(*
The callstack for the allocation.
*)

}

The type of metadata associated with allocations. This is the type of records passed to the callback triggered by the sampling of an allocation.

Sourcetype ('minor, 'major) tracker = {

alloc_minor : allocation -> 'minor option;
alloc_major : allocation -> 'major option;
promote : 'minor -> 'major option;
dealloc_minor : 'minor -> unit;
dealloc_major : 'major -> unit;

}

A ('minor, 'major) tracker describes how memprof should track sampled blocks over their lifetime, keeping a user-defined piece of metadata for each of them: 'minor is the type of metadata to keep for minor blocks, and 'major the type of metadata for major blocks.

When using threads, it is guaranteed that allocation callbacks are always run in the thread where the allocation takes place.

If an allocation-tracking or promotion-tracking function returns None, memprof stops tracking the corresponding value.

Sourceval null_tracker : ('minor, 'major) tracker

Default callbacks simply return None or ()

Source

val start : 
  sampling_rate:float ->
  ?callstack_size:int ->
  ('minor, 'major) tracker ->
  unit

Start the sampling with the given parameters. Fails if sampling is already active.

The parameter sampling_rate is the sampling rate in samples per word (including headers). Usually, with cheap callbacks, a rate of 1e-4 has no visible effect on performance, and 1e-3 causes the program to run a few percent slower

The parameter callstack_size is the length of the callstack recorded at every sample. Its default is max_int.

The parameter tracker determines how to track sampled blocks over their lifetime in the minor and major heap.

Sampling is temporarily disabled when calling a callback for the current thread. So they do not need to be re-entrant if the program is single-threaded. However, if threads are used, it is possible that a context switch occurs during a callback, in this case the callback functions must be re-entrant.

Note that the callback can be postponed slightly after the actual event. The callstack passed to the callback is always accurate, but the program state may have evolved.

Sourceval stop : unit -> unit

Stop the sampling. Fails if sampling is not active.

This function does not allocate memory.

All the already tracked blocks are discarded. If there are pending postponed callbacks, they may be discarded.

Calling stop when a callback is running can lead to callbacks not being called even though some events happened.