Hi, On 8 August 2016 at 16:09, hubo <h...@jiedaibao.com> wrote: > P.S. it is interesting that though I thought recv_into() should be more > efficient thant recv() since it reduces extra object creation / destruction, > the test result shows that recv() outperforms recv_into(), even with > CPython. With CPython, it seems server with recv() costs less CPU time than > recv_into(), but having the same I/O performance.
As you found out, recv_into() is not better than recv() in your use case. (There are other use cases where it can be useful, e.g. to receive in the middle of a buffer where there is already some data in the beginning of the buffer and you want all data concatenated.) Indeed, the current PyPy implementation of recv_into() is definitely bad. It just does a regular recv(), and then it manually copies the data into the buffer! So it always done one more copy of the data than recv(). I just fixed it in e53ea5c9c384. Now in PyPy (like in CPython), both recv() and recv_into() don't copy the received data at all. The difference between the two in this case is completely lost in the noise---it's the difference between doing a malloc or not, which costs nothing compared to transferring 2MB of data from the kernel to userspace. A bientôt, Armin. _______________________________________________ pypy-dev mailing list pypy-dev@python.org https://mail.python.org/mailman/listinfo/pypy-dev
