[Python-Dev] Python 3.4, marshal dumps slower (version 3 protocol)

[Wolfgang]

Hi,

I tested the latest beta from 3.4 (b3) and noticed there is a new marshal
protocol version 3.
The documentation is a little silent about the new features, not going into
detail.

I've run a performance test with the new protocol version and noticed the
new version is two times slower in serialization than version 2. I tested
it with a simple value tuple in a list (500000 elements).
Nothing special. (happens only if the tuple contains also a tuple)

Copy of the test code:


from time import time
from marshal import dumps

def genData(amount=500000):
  for i in range(amount):
    yield (i, i+2, i*2, (i+1,i+4,i,4), "my string template %s" % i, 1.01*i,
True)

data = list(genData())
print(len(data))
t0 = time()
result = dumps(data, 2)
t1 = time()
print("duration p2: %f" % (t1-t0))
t0 = time()
result = dumps(data, 3)
t1 = time()
print("duration p3: %f" % (t1-t0))



Is the overhead for the recursion detection so high ?

Note this happens only if there is a tuple in the tuple of the datalist.


Regards,

Wolfgang
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