Maxima的ezunit中的比较(例如<)在Maxima 5.42.0中要比5.41.0慢得多

Question

对我来说，这个比较的运行时:Maxima5.42.0(以及5.42.2、5.43.0和5.43.2)中的1`g < 2`g似乎比5.41.0慢得多。(请注意，第一次运行总是比较慢。)

在5.41.0和5.42.0之间是否有可能导致这种放缓？还是我做错什么了？

示例运行时：

Maxima 5.41.0与SBCL 1.5.7

Maxima 5.41.0 http://maxima.sourceforge.net
using Lisp SBCL 1.5.7
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) showtime:true;
Evaluation took 0.0000 seconds (0.0000 elapsed) using 0 bytes.
(%o1)                                true
(%i2) load(ezunits);
Evaluation took 2.7650 seconds (2.7780 elapsed) using 1046.148 MB.
(%o2)      /usr/local/share/maxima/5.41.0/share/ezunits/ezunits.mac
(%i3) 1`g < 1`g;
Evaluation took 0.0860 seconds (0.0860 elapsed) using 33.078 MB.
(%o3)                                1 < 1
(%i4) 1`g < 1`g;
Evaluation took 0.0040 seconds (0.0040 elapsed) using 511.469 KB.
(%o4)                                1 < 1
(%i5) 1`g < 1`g;
Evaluation took 0.0040 seconds (0.0040 elapsed) using 543.547 KB.
(%o5)                                1 < 1

Maxima5.42.0与SBCL 1.5.7

Maxima 5.42.0 http://maxima.sourceforge.net
using Lisp SBCL 1.5.7
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) showtime:true;
Evaluation took 0.0000 seconds (0.0010 elapsed) using 0 bytes.
(%o1)                                true
(%i2) load(ezunits);
Evaluation took 2.6460 seconds (2.6600 elapsed) using 1033.502 MB.
(%o2)      /usr/local/share/maxima/5.42.0/share/ezunits/ezunits.mac
(%i3) 1`g < 2`g;
Evaluation took 1.0400 seconds (1.0400 elapsed) using 434.087 MB.
(%o3)                                1 < 2
(%i4) 1`g < 2`g;
Evaluation took 0.4350 seconds (0.4360 elapsed) using 170.099 MB.
(%o4)                                1 < 2
(%i5) 1`g < 2`g;
Evaluation took 0.4330 seconds (0.4340 elapsed) using 170.119 MB.
(%o5)                                1 < 2

这似乎与Lisp版本无关。

Maxima 5.42.0与Clisp 2.49

Maxima 5.42.0 http://maxima.sourceforge.net
using Lisp CLISP 2.49 (2010-07-07)
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) showtime:true;
Evaluation took 0.0000 seconds (0.0000 elapsed) using 56 bytes.
(%o1)                                true
(%i2) load(ezunits);
Evaluation took 5.4127 seconds (5.4136 elapsed) using 82.926 MB.
(%o2)      /usr/local/share/maxima/5.42.0/share/ezunits/ezunits.mac
(%i3) 1`g < 2`g;
Evaluation took 1.7984 seconds (1.7984 elapsed) using 53.569 MB.
(%o3)                                1 < 2
(%i4) 1`g < 2`g;
Evaluation took 0.1951 seconds (0.1951 elapsed) using 3.291 MB.
(%o4)                                1 < 2
(%i5) 1`g < 2`g;
Evaluation took 0.1597 seconds (0.1598 elapsed) using 3.291 MB.
(%o5)                                1 < 2

我自己在Docker中编译了Maxima和Lisp版本，这样我就可以使用以下命令在AWS Lambda上运行它：

wget --quiet --output-document sbcl-1.5.7-source.tar.bz2 https://sourceforge.net/projects/sbcl/files/sbcl/1.5.7/sbcl-1.5.7-source.tar.bz2/download \
    && tar --bzip2 -xf sbcl-1.5.7-source.tar.bz2 \
    && cd sbcl-1.5.7 \
    && sh make.sh "clisp" \
    && sh install.sh

wget --quiet --output-document maxima-5.42.0.tar.gz https://sourceforge.net/projects/maxima/files/Maxima-source/5.42.0-source/maxima-5.42.0.tar.gz/download \
    && tar -xzvf maxima-5.42.0.tar.gz \
    && cd maxima-5.42.0 \
    && ./configure --enable-sbcl-exec \
    && make \
    && make install

更新

我们已经试着亲自调查这个问题了。不幸的是，我们对lisp缺乏足够的经验，无法找到解决方案。

我们发现，当我们使用GCL预编译的Maxima5.43.0版本时，性能很好。这个版本可以在这里找到：https://sourceforge.net/projects/maxima/files/Maxima-Linux/5.43.0-Linux/

Maxima 5.43.0与GCL 2.6.12

Maxima 5.43.0 http://maxima.sourceforge.net
using Lisp GNU Common Lisp (GCL) GCL 2.6.12
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) showtime:true;
Evaluation took 0.0000 seconds (0.0000 elapsed)
(%o1)                                true
(%i2) load(ezunits);
Evaluation took 0.4100 seconds (0.5600 elapsed)
(%o2)         /usr/share/maxima/5.43.0/share/ezunits/ezunits.mac
(%i3) 1`g < 2`g;
Evaluation took 0.1700 seconds (0.1700 elapsed)
(%o3)                                1 < 2
(%i4) 1`g < 2`g;
Evaluation took 0.0500 seconds (0.0500 elapsed)
(%o4)                                1 < 2

这也是在码头集装箱中运行的。Maxima是使用以下命令安装的：

wget --quiet https://downloads.sourceforge.net/project/maxima/Maxima-Linux/5.43.0-Linux/maxima-5.43.0-1.x86_64.rpm \
    && wget --quiet https://downloads.sourceforge.net/project/maxima/Maxima-Linux/5.43.0-Linux/maxima-exec-gcl-5.43.0-1.x86_64.rpm \
    && rpm --install --verbose --hash maxima-5.43.0-1.x86_64.rpm maxima-exec-gcl-5.43.0-1.x86_64.rpm

Answer 1

跟踪一些涉及到的函数，看起来处理1 ` g < 2 ` g的时间中最大的一部分花费在dimensions中，这是一个用于计算单元尺寸(质量、时间、长度等)的函数，而在dimensions中，大部分时间花费在一个名为rff的表达式匹配规则中，该规则如下所示：

(%i22) disprule(rff);
(%t22) rff : dimensions(ff%) -> block([ff%2 : 
ev(ff%, args(known_unit_conversions), infeval)], 
if ff%2 # ff% then dimensions(ff%2) else dimensions(ff%))

这里，ff%是像g这样的符号。rff的作用是将g转换为kg/1000，然后在kg (和1000)上操作其他规则，发现维度是mass。

ev(ff%, args(known_unit_conversions), infeval)是查找基本单元的一种简单方法，但正如您所指出的，它相对缓慢，因为它将整个单元转换列表输入到图片中，而只有一个是真正需要的。我同意一个更有效的方法是可取的，因为这样可能会加快一般单位的运作速度。请随时提交关于此问题的错误报告(https://sourceforge.net/p/maxima/bugs/)。

我没有查看提交历史，所以我不知道不同版本之间发生了什么变化。无论如何，似乎很清楚，目前版本的瓶颈在哪里。