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The problem with a fixed count value is that it result in varying degrees of performance and memory impact proportions depending on the usage pattern of each script. E.g. if a script keeps using the same 1M objects, then a threshold of 10K objects will result in GC cycles which free only 1% of objects, which is hugely wasteful in terms of performance. On the other hand, if a script only uses 100 objects then a threshold of 10K means it uses 100 times more memory than it actually needs before GC triggers. Now the threshold is a target memory usage factor (of the minimum needed memory) which GC tries to aim at. This makes the GC impact have constant proportions. The default aims at a memory usage factor of 5, i.e. 80% garbage and 20% remaining on each GC cycle. The factor is only a target/goal because the actual overhead is not known until GC completes. However, most scripts exhibit consistent enough behavior such that the real overhead is within 10% or less of the goal even when the usage pattern changes over time. Within the v8 bench test suite, the actual GC threshold count varies between ~50K to ~500K, where only one test (raytrace.js) stabilizes on less than 10K (the previous fixed default) - at about 9K and its score decreases by ~5%. The splay.js score increases about x12 fold (or x50 fold from the previous commit which counts properties), other tests quite a bit less or none at all, and the overall score increases by nearly 40%. Also, change the count type from int to unsigned int to get twice the range. Preferably we should make it even bigger, maybe uint64_t. For instance the splay.js v8 bench test surpasses million non-garbage allocations within few seconds (that's why its score increased so much with a proportional overhead), and the default GC threshold is 5 times that number.
MuJS: an embeddable Javascript interpreter in C. ABOUT MuJS is a lightweight Javascript interpreter designed for embedding in other software to extend them with scripting capabilities. LICENSE MuJS is Copyright 2013-2017 Artifex Software, Inc. Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. The software is provided "as is" and the author disclaims all warranties with regard to this software including all implied warranties of merchantability and fitness. In no event shall the author be liable for any special, direct, indirect, or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of this software. COMPILING If you are building from source you can either use the provided Unix Makefile: make release Or compile the source with your preferred compiler: cc -O2 -c one.c -o libmujs.o INSTALLING To install the MuJS command line interpreter, static library and header file: make prefix=/usr/local install DOWNLOAD The latest development source is available directly from the git repository: git clone http://git.ghostscript.com/mujs.git REPORTING BUGS AND PROBLEMS Report bugs on the ghostscript bugzilla, with MuJS as the selected component. http://bugs.ghostscript.com/ The MuJS developers hang out on IRC in the #mupdf channel on irc.freenode.net.