[Python-Dev] eval() slowdown in 2.2 on MacOS X?

[Skip Montanaro]

    >> BTW, I forgot to pass this on yesterday, but I tried the code in Tim
    >> Peters' e-mail yesterday and the delay happens during the code =
    >> compile(...)  statement.

I saw the same effect on my Linux laptop (with a mere 128MB).  The disk went
nuts when it tried compiling

    "[" + "2," * 200000 + "]"

VM size as reported by top went to 98.5MB.  This does not appear to be
exclusively a 2.2 issue, as I got this with the fresh 2.1.2 I built this
morning.

If you consider what this compiles to:

     LOAD_CONST               1 (2)
     LOAD_CONST               1 (2)
     LOAD_CONST               1 (2)
     LOAD_CONST               1 (2)
     ...
     LOAD_CONST               1 (2)
     LOAD_CONST               1 (2)
     LOAD_CONST               1 (2)
     LOAD_CONST               1 (2)
     BUILD_LIST               200000

To generate that it has to generate and parse a pretty deep abstract syntax
tree.  It looks like symtable_node gets called once for each list element.
There are probably other functions that are called once per list element as
well.   

Skip