How Big can a Python List Get?

How Big can a Python List Get?

According to the source code, the maximum size of a list is PY_SSIZE_T_MAX/sizeof(PyObject*).

PY_SSIZE_T_MAX is defined in pyport.h to be ((size_t) -1)>>1

On a regular 32bit system, this is (4294967295 / 2) / 4 or 536870912.

Therefore the maximum size of a python list on a 32 bit system is 536,870,912 elements.

As long as the number of elements you have is equal or below this, all list functions should operate correctly.

As the Python documentation says:


The largest positive integer supported by the platform’s Py_ssize_t type, and thus the maximum size lists, strings, dicts, and many other containers can have.

In my computer (Linux x86_64):

>>> import sys
>>> print sys.maxsize

How Big can a Python List Get?

Sure it is OK. Actually you can see for yourself easily:

l = range(12000)
l = sorted(l, reverse=True)

Running the those lines on my machine took:

real    0m0.036s
user    0m0.024s
sys  0m0.004s

But sure as everyone else said. The larger the array the slower the operations will be.

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