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NAME

ocamlrun - The OCaml bytecode interpreter

SYNOPSIS

ocamlrun [ options ] filename argument ...

DESCRIPTION

The ocamlrun(1) command executes bytecode files produced by the linking phase of the ocamlc(1) command.

The first non-option argument is taken to be the name of the file containing the executable bytecode. (That file is searched in the executable path as well as in the current directory.) The remaining arguments are passed to the OCaml program, in the string array Sys.argv. Element 0 of this array is the name of the bytecode executable file; elements 1 to n are the remaining arguments.

In most cases, the bytecode executable files produced by the ocamlc(1) command are self-executable, and manage to launch the ocamlrun(1) command on themselves automatically.

OPTIONS

The following command-line options are recognized by ocamlrun(1).

-m file

Print the magic number of the bytecode executable file and exit.

-version

Print version string and exit.

ENVIRONMENT VARIABLES

The following environment variable are also consulted:
CAML_LD_LIBRARY_PATH

Additional directories to search for dynamically-loaded libraries.

OCAMLLIB

The directory containing the OCaml standard library. (If OCAMLLIB is not set, CAMLLIB will be used instead.) Used to locate the ld.conf configuration file for dynamic loading. If not set, default to the library directory specified when compiling OCaml.

OCAMLRUNPARAM

Set the runtime system options and garbage collection parameters. (If OCAMLRUNPARAM is not set, CAMLRUNPARAM will be used instead.) This variable must be a sequence of parameter specifications separated by commas. A parameter specification is a letter, optionally followed by an = sign, a decimal number (or a hexadecimal number prefixed by 0x), and an optional multiplier. If the letter is followed by anything else, the corresponding option is set to 1. Unknown letters are ignored. The options are documented below; the options a, i, l, m, M, n, o, O, s, v, w correspond to the fields of the control record documented in The OCaml user’s manual, chapter "Standard Library", section "Gc".
a (allocation_policy)

The policy used for allocating in the OCaml heap. Possible values are 0 for the next-fit policy, 1 for the first-fit policy, and 2 for the best-fit policy. The default is 2. See the Gc module documentation for details.

i (major_heap_increment)

The default size increment for the major heap (in words if greater than 1000, else in percents of the heap size).

l (stack_limit)

The limit (in words) of the stack size.

m (custom_minor_ratio)

Bound on floating garbage for out-of-heap memory held by custom values in the minor heap. A minor GC is triggered when this much memory is held by custom values located in the minor heap. Expressed as a percentage of minor heap size. Note: this only applies to values allocated with caml_alloc_custom_mem (e.g. bigarrays).
Default: 100.

M (custom_major_ratio)

Target ratio of floating garbage to major heap size for out-of-heap memory held by custom values located in the major heap. The GC speed is adjusted to try to use this much memory for dead values that are not yet collected. Expressed as a percentage of major heap size. The default value keeps the out-of-heap floating garbage about the same size as the in-heap overhead. Note: this only applies to values allocated with caml_alloc_custom_mem (e.g. bigarrays). Default: 44.

n (custom_minor_max_size)

Maximum amount of out-of-heap memory for each custom value allocated in the minor heap. When a custom value is allocated on the minor heap and holds more than this many bytes, only this value is counted against custom_minor_ratio and the rest is directly counted against custom_major_ratio. Note: this only applies to values allocated with caml_alloc_custom_mem (e.g. bigarrays). Default: 8192 bytes.

o (space_overhead)

The major GC speed setting.

O (max_overhead)

The heap compaction trigger setting.

s (minor_heap_size)

The size of the minor heap (in words).

v (verbose)

What GC messages to print to stderr. This is a sum of values selected from the following:

0x001 Start and end of major GC cycle.

0x002 Minor collection and major GC slice.

0x004 Growing and shrinking of the heap.

0x008 Resizing of stacks and memory manager tables.

0x010 Heap compaction.

0x020 Change of GC parameters.

0x040 Computation of major GC slice size.

0x080 Calling of finalisation functions.

0x100 Startup messages (loading the bytecode executable file, resolving shared libraries).

0x200 Computation of compaction-triggering condition.

0x400 Output GC statistics at program exit, in the same format as Gc.print_stat.

w (window_size)

Set size of the window used by major GC for smoothing out variations in its workload. This is an integer between 1 and 50. (Default: 1)

The multiplier is k, M, or G, for multiplication by 2^10, 2^20, and 2^30 respectively.

If the option letter is not recognized, the whole parameter is ignored; if the equal sign or the number is missing, the value is taken as 1; if the multiplier is not recognized, it is ignored.

For example, on a 32-bit machine under bash, the command export OCAMLRUNPARAM=’s=256k,v=1’ tells a subsequent ocamlrun to set its initial minor heap size to 1 megabyte and to print a message at the start of each major GC cycle.
CAMLRUNPARAM

If OCAMLRUNPARAM is not found in the environment, then CAMLRUNPARAM will be used instead. If CAMLRUNPARAM is also not found, then the default values will be used.

SEE ALSO

ocamlc(1).
The OCaml user’s manual, chapter "Runtime system".