why is bytearray treated so inefficiently by pickle?

[Irmen de Jong]

Hi,

A bytearray is pickled (using max protocol) as follows:

>>> pickletools.dis(pickle.dumps(bytearray([255]*10),2))
    0: \x80 PROTO      2
    2: c    GLOBAL     '__builtin__ bytearray'
   25: q    BINPUT     0
   27: X    BINUNICODE u'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff'
   52: q    BINPUT     1
   54: U    SHORT_BINSTRING 'latin-1'
   63: q    BINPUT     2
   65: \x86 TUPLE2
   66: q    BINPUT     3
   68: R    REDUCE
   69: q    BINPUT     4
   71: .    STOP

>>> bytearray("\xff"*10).__reduce__()
(<type 'bytearray'>, (u'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff', 'latin-1'), None)


Is there a particular reason it is encoded so inefficiently? Most notably, the actual
*bytes* in the bytearray are represented by an UTF-8 string. This needs to be
transformed into a unicode string and then encoded back into bytes, when unpickled. The
thing being a bytearray, I would expect it to be pickled as such: a sequence of bytes.
And then possibly converted back to bytearray using the constructor that takes the bytes
directly (BINSTRING/BINBYTES pickle opcodes).

The above occurs both on Python 2.x and 3.x.

Any ideas? Candidate for a patch?


Irmen.