PyPy significantly slower than CPython
I've been testing a cacheing system of my making. Its purpose is to speed up a Django web application. It stores everything in-memory. According to cProfile most of the time in my tests is spent inside QuerySet._clone() which turns out to be terribly inefficient (it's actually not that strange given the implementation).
I was having high hopes for using PyPy to speed things up. I've got a 64-bit machine. However after installing all the required libraries it turns out that PyPy compiled code runs about 2.5x slower than regular Python code, and I don't know what to make out of it. The code is CPU bound (there are absolutely no database queries, so IO-bounding is not an option). A single test runs for about 10 seconds, so I guess it should be enough for JIT to kick in. I'm using PyPy 1.5. One note - I didn't compile the sources myself, just downloaded a 64-bit linux version.
I'd like to know how frequent it is for a CPU intensive code to actually run slower under PyPy. Is there hopefully something wrong I could have done that would prevent PyPy from running at its best.
EDIT
Exact cPython output:
PyPy 1.5:
3439146 function calls (3218654 primitive calls) in 19.094 seconds
Ordered by: cumulative time
ncalls tottime percall cumtime percall filename:lineno(function)
2/1 0.000 0.000 18.956 18.956 <string>:1(<module>)
2/1 0.000 0.000 18.956 18.956 /path/to/my/project/common/integrity/models/transactions.py:200(newfn)
2/1 0.000 0.000 18.956 18.956 /path/to/my/project/common/integrity/models/transactions.py:134(recur)
2/1 0.000 0.000 18.956 18.956 /usr/local/pypy/site-packages/django/db/transaction.py:210(inner)
2/1 0.172 0.086 18.899 18.899 /path/to/my/project/common/integrity/tests/optimization.py:369(func_cached)
9990 0.122 0.000 18.632 0.002 /usr/local/pypy/site-packages/django/db/models/manager.py:131(get)
9990 0.127 0.000 16.638 0.002 /path/to/my/project/common/integrity/models/cache.py:1068(get)
9990 0.073 0.000 12.478 0.001 /usr/local/pypy/site-packages/django/db/models/query.py:547(filter)
9990 0.263 0.000 12.405 0.001 /path/to/my/project/common/integrity/models/cache.py:1047(_filter_or_exclude)
9990 0.226 0.000 12.096 0.001 /usr/local/pypy/site-packages/django/db/models/query.py:561(_filter_or_exclude)
9990 0.187 0.000 8.383 0.001 /path/to/my/project/common/integrity/models/cache.py:765(_clone)
9990 0.212 0.000 7.662 0.001 /usr/local/pypy/site-packages/django/db/models/query.py:772(_clone)
9990 1.025 0.000 7.125 0.001 /usr/local/pypy/site-packages/django/db/models/sql/query.py:226(clone)
129942/49972 1.674 0.000 6.021 0.000 /usr/local/pypy/lib-python/2.7/copy.py:145(deepcopy)
140575/110605 0.120 0.000 4.066 0.000 {len}
9990 0.182 0.000 3.972 0.000 /usr/local/pypy/site-packages/django/db/models/query.py:74(__len__)
19980 0.260 0.000 3.777 0.000 /path/to/my/project/common/integrity/models/cache.py:1062(iterator)
9990 0.255 0.000 3.154 0.000 /usr/local/pypy/site-packages/django/db/models/sql/query.py:1149(add_q)
9990 0.210 0.000 3.073 0.000 /path/to/my/project/common/integrity/models/cache.py:973(_query)
9990 0.371 0.000 2.316 0.000 /usr/local/pypy/site-packages/django/db/models/sql/query.py:997(add_filter)
9990 0.364 0.000 2.168 0.000 /path/to/my/project/common/integrity/models/cache.py:892(_deduct)
29974/9994 0.448 0.000 2.078 0.000 /usr/local/pypy/lib-python/2.7/copy.py:234(_deepcopy_tuple)
19990 0.362 0.000 2.065 0.000 /path/to/my/project/common/integrity/models/cache.py:566(__init__)
10000 0.086 0.000 1.874 0.000 /path/to/my/project/common/integrity/models/cache.py:1090(get_query_set)
19990 0.269 0.000 1.703 0.000 /usr/local/pypy/site-packages/django/db/models/query.py:31(__init__)
9990 0.122 0.000 1.643 0.000 /path/to/my/project/common/integrity/models/cache.py:836(_deduct_recur)
19980 0.274 0.000 1.636 0.000 /usr/local/pypy/site-packages/django/utils/tree.py:55(__deepcopy__)
9990 0.607 0.000 1.458 0.000 /path/to/my/project/common/integrity/models/cache.py:789(_deduct_local)
10020 0.633 0.000 1.437 0.000 /usr/local/pypy/site-packages/django/db/models/sql/query.py:99(__init__)
129942 0.841 0.000 1.191 0.000 /usr/local/pypy/lib-python/2.7/copy.py:267(_keep_alive)
9994/9992 0.201 0.000 1.019 0.000 /usr/local/pypy/lib-python/2.7/copy.py:306(_reconstruct)
Python 2.7:
3326403 function calls (3206359 primitive calls) in 12.430 CPU seconds
Ordered by: cumulative time
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 12.457 12.457 <string>:1(<module>)
1 0.000 0.000 12.457 12.457 /path/to/my/project/common/integrity/models/transactions.py:200(newfn)
1 0.000 0.000 12.457 12.457 /path/to/my/project/common/integrity/models/transactions.py:134(recur)
1 0.000 0.000 12.457 12.457 /usr/local/lib/python2.7/dist-packages/django/db/transaction.py:210(inner)
1 0.000 0.000 12.457 12.457 /path/to/my/project/common/integrity/models/transactions.py:165(recur2)
1 0.089 0.089 12.450 12.450 /path/to/my/project/common/integrity/tests/optimization.py:369(func_cached)
9990 0.198 0.000 12.269 0.001 /usr/local/lib/python2.7/dist-packages/django/db/models/manager.py:131(get)
9990 0.087 0.000 11.281 0.001 /path/to/my/project/common/integrity/models/cache.py:1068(get)
9990 0.040 0.000 8.161 0.001 /usr/local/lib/python2.7/dist-packages/django/db/models/query.py:547(filter)
9990 0.110 0.000 8.121 0.001 /path/to/my/project/common/integrity/models/cache.py:1047(_filter_or_exclude)
9990 0.127 0.000 7.983 0.001 /usr/local/lib/python2.7/dist-packages/django/db/models/query.py:561(_filter_or_exclude)
9990 0.100 0.000 5.593 0.001 /path/to/my/project/common/integrity/models/cache.py:765(_clone)
9990 0.122 0.000 5.125 0.001 /usr/local/lib/python2.7/dist-packages/django/db/models/query.py:772(_clone)
9990 0.405 0.000 4.899 0.000 /usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py:226(clone)
129942/49972 1.456 0.000 4.505 0.000 /usr/lib/python2.7/copy.py:145(deepcopy)
129899/99929 0.191 0.000 3.117 0.000 {len}
9990 0.111 0.000 2.968 0.000 /usr/local/lib/python2.7/dist-packages/django/db/models/query.py:74(__len__)
19980 0.070 0.000 2.843 0.000 /path/to/my/project/common/integrity/models/cache.py:1062(iterator)
9990 0.208 0.000 2.190 0.000 /path/to/my/project/common/integrity/models/cache.py:973(_query)
9990 0.182 0.000 2.114 0.000 /usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py:1149(add_q)
19984/9994 0.291 0.000 1.644 0.000 /usr/lib/python2.7/copy.py:234(_deepcopy_tuple)
9990 0.288 0.000 1.599 0.000 /usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py:997(add_filter)
9990 0.171 0.000 1.454 0.000 /path/to/my/project/common/integrity/models/cache.py:892(_deduct)
19980 0.177 0.000 1.208 0.000 /usr/local/lib/python2.7/dist-packages/django/utils/tree.py:55(__deepcopy__)
9990 0.099 0.000 1.199 0.000 /path/to/my/project/common/integrity/models/cache.py:836(_deduct_recur)
9990 0.349 0.000 1.040 0.000 /path/to/my/project/common/integrity/models/cache.py:789(_deduct_local)
Brushing aside the fact that PyPy might really be intrinsically slower for your case, there are some factors that could be making it unnecessarily slower:
You can also check the JIT Friendliness wiki page for more hints about what can make PyPy slower. A nightly build will probably be faster too, as there are many improvements relative to 1.5.
A more detailed description of your stack (server, OS, DB) and setup (how did you benchmark? how many queries?) would allow us to give better answers.
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