Self-collecting mutators for the C programming language

• Copyright (c) 2010, the Short-term Memory Project Authors.
• All rights reserved. Please see the AUTHORS file for details.
• Use of this source code is governed by a BSD license that
• can be found in the LICENSE file.

Self-collecting mutators implement the short-term memory model described in:

@InProceedings{ISMM11, author = {M. Aigner and A. Haas and C.M. Kirsch and M. Lippautz and A. Sokolova and S. Stroka and A. Unterweger}, title = {Short-term Memory for Self-collecting Mutators}, booktitle = {Proc. International Symposium on Memory Management (ISMM)}, year = {2011}, publisher = {ACM} }

Abstract:

We propose a new memory model for heap management, called short-term memory, and concurrent implementations of short-term memory for Java and C, called self-collecting mutators. In short-term memory objects on the heap expire after a finite amount of time, which makes deallocation unnecessary. Self-collecting mutators require programmer support to control the progress of time and thereby enable reclaiming the memory of expired objects. We identify a class of programs for which programmer support is easy and correctness is guaranteed. Self-collecting mutators perform competitively with garbage-collected and explicitly managed systems, as shown by our experimental results on several benchmarks. Unlike garbage-collected systems, self-collecting mutators do not introduce pause times and provide constant execution time of all operations, independent of the number of live objects, and constant (short-term) memory consumption after a steady state has been reached. Self-collecting mutators can be linked against any unmodified C code introducing a one-word overhead per heap object and negligible runtime overhead. Short-term memory may then be used to remove explicit deallocation of some but not necessarily all objects.

The latest version also supports regions and multiple clocks.

• Use a recent version of gcc. libscm is known to work with gcc 4.4.3 on Linux x86.
• Run make to build the shared library.
• The library (libscm.so) and the public header files reside in the dist subdirectory.
• Take a look at the examples subdirectory (C files and Makefile) to find out how to build a program using libscm, see also the run-examples.sh script.
• There is also a port of sh6bench for benchmarking libscm in bench/sh6bench, see the run-bench.sh script.

Take a look at our project webpage:

http://tiptoe.cs.uni-salzburg.at/short-term-memory/

Detailed information regarding the implementation can be found here:

http://cs.uni-salzburg.at/~maigner/publications/masters_thesis.pdf