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[;1m-spec erlang:memory() -> [{Type, Size}][0m
[;1m when[0m
[;1m Type :: memory_type(),[0m
[;1m Size :: non_neg_integer().[0m
Types:
-type memory_type() ::
total | processes | processes_used | system | atom |
atom_used | binary | code | ets.
Returns a list with information about memory dynamically allocated
by the Erlang emulator. Each list element is a tuple [;;4m{Type, Size}[0m.
The first element [;;4mType[0m is an atom describing memory type. The
second element [;;4mSize[0m is the memory size in bytes.
Memory types:
[;;4m[;;4mtotal[0m[0m:
The total amount of memory currently allocated. This is the
same as the sum of the memory size for [;;4mprocesses[0m and [;;4msystem[0m.
[;;4m[;;4mprocesses[0m[0m:
The total amount of memory currently allocated for the Erlang
processes.
[;;4m[;;4mprocesses_used[0m[0m:
The total amount of memory currently used by the Erlang
processes. This is part of the memory presented as [;;4mprocesses[0m
memory.
[;;4m[;;4msystem[0m[0m:
The total amount of memory currently allocated for the
emulator that is not directly related to any Erlang process.
Memory presented as [;;4mprocesses[0m is not included in this
memory. [;;4minstrument(3)[0m can be used to get a more detailed
breakdown of what memory is part of this type.
[;;4m[;;4matom[0m[0m:
The total amount of memory currently allocated for atoms. This
memory is part of the memory presented as [;;4msystem[0m memory.
[;;4m[;;4matom_used[0m[0m:
The total amount of memory currently used for atoms. This
memory is part of the memory presented as [;;4matom[0m memory.
[;;4m[;;4mbinary[0m[0m:
The total amount of memory currently allocated for binaries.
This memory is part of the memory presented as [;;4msystem[0m
memory.
[;;4m[;;4mcode[0m[0m:
The total amount of memory currently allocated for Erlang
code. This memory is part of the memory presented as [;;4msystem[0m
memory.
[;;4m[;;4mets[0m[0m:
The total amount of memory currently allocated for ETS tables.
This memory is part of the memory presented as [;;4msystem[0m
memory.
[;;4m[;;4mlow[0m[0m:
Only on 64-bit halfword emulator. The total amount of memory
allocated in low memory areas that are restricted to < 4 GB,
although the system can have more memory.
Can be removed in a future release of the halfword emulator.
[;;4m[;;4mmaximum[0m[0m:
The maximum total amount of memory allocated since the
emulator was started. This tuple is only present when the
emulator is run with instrumentation.
For information on how to run the emulator with
instrumentation, see [;;4minstrument(3)[0m and/or [;;4merl(1)[0m.
Note:
The [;;4msystem[0m value is not complete. Some allocated memory that
is to be part of this value is not.
When the emulator is run with instrumentation, the [;;4msystem[0m
value is more accurate, but memory directly allocated for [;;4m[0m
[;;4mmalloc[0m (and friends) is still not part of the [;;4msystem[0m value.
Direct calls to [;;4mmalloc[0m are only done from OS-specific
runtime libraries and perhaps from user-implemented Erlang
drivers that do not use the memory allocation functions in the
driver interface.
As the [;;4mtotal[0m value is the sum of [;;4mprocesses[0m and [;;4msystem[0m,
the error in [;;4msystem[0m propagates to the [;;4mtotal[0m value.
The different amounts of memory that are summed are not
gathered atomically, which introduces an error in the result.
The different values have the following relation to each other.
Values beginning with an uppercase letter is not part of the
result.
total = processes + system
processes = processes_used + ProcessesNotUsed
system = atom + binary + code + ets + OtherSystem
atom = atom_used + AtomNotUsed
RealTotal = processes + RealSystem
RealSystem = system + MissedSystem
More tuples in the returned list can be added in a future release.
Note:
The [;;4mtotal[0m value is supposed to be the total amount of memory
dynamically allocated by the emulator. Shared libraries, the
code of the emulator itself, and the emulator stacks are not
supposed to be included. That is, the [;;4mtotal[0m value is not
supposed to be equal to the total size of all pages mapped to
the emulator.
Also, because of fragmentation and prereservation of memory
areas, the size of the memory segments containing the
dynamically allocated memory blocks can be much larger than
the total size of the dynamically allocated memory blocks.
Note:
As from ERTS 5.6.4, [;;4merlang:memory/0[0m requires that all [;;4m[0m
[;;4merts_alloc(3)[0m allocators are enabled (default behavior).
Failure: [;;4mnotsup[0m if an [;;4merts_alloc(3)[0m allocator has been
disabled.
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