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Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 58 |
1 files changed, 58 insertions, 0 deletions
@@ -206,6 +206,13 @@ supports that behavior, or even that exact version. For more information, see the COMPATIBILITY section. +.IP "--gc-delta=number" + +The argument to this option must be a decimal integer. It represents +a megabyte value, the "GC delta": one megabyte is 1048576 bytes. The "GC +delta" controls an aspect of the garbage collector behavior. +See the gc-set-delta function for a description. + .IP --help Prints usage summary on standard output, and terminates successfully. @@ -15839,6 +15846,57 @@ pprof prints these statistics are printed in a concise report on the The pprof macro relies on the prof operator. +.SH GARBAGE COLLECTION + +.SS Function sys:gc + +.TP +Syntax: + + (sys:gc) + +.TP +Description: + +The gc function triggers garbage collection. Garbage collection means +that unreachable objects are identified and reclaimed, so that their +storage can be re-used. + +.SS Function sys:gc-set-delta + +.TP +Syntax: + + (sys:gc-set-delta <bytes>) + +.TP +Description: + +The gc-set-delta function sets the GC delta parameter. + +Note: This function may disappear in a future release of TXR or suffer +a backward-incompatible change in its syntax or behavior. + +When the amount of new dynamic memory allocated since the last garbage +collection equals or exceeds the GC delta, a garbage collection pass is +triggered. From that point, a new delta begins to be accumulated. + +Dynamic memory is used for allocating heaps of small garbage-collected objects +such as cons cells, as well as the satellite data attached to some objects: +like the storage arrays of vectors, strings or bignum integers. Most garbage +collector behaviors are based on counting objects in the heaps. + +Sometimes a program works with a small number of objects which are very large, +frequently allocating new, large objects and turning old ones into garbage. +For instance a single large integer could be many megabytes long. In such a +situation, a small number of heap objects therefore control a large amount of +memory. This requires garbage collection to be triggered much more often than +when working with small objects, such as conses, to prevent runaway allocation +of memory. It is for this reason that the garbage collector uses the GC delta. + +There is a default GC delta of 64 megabytes. This may be overridden in +special builds of TXR for small systems. + .SH MODULARIZATION .SS Special variable *self-path* |