Mercurial > cpython-lru_cache-weakref
diff Python/ceval.c @ 49940:3344804f327d legacy-trunk
Speed up Python (according to pybench and 2to3-on-itself) by 1-2% by caching
whether any thread has tracing turned on, which saves one load instruction in
the fast_next_opcode path in PyEval_EvalFrameEx(). See issue 4477.
| author | Jeffrey Yasskin <jyasskin@gmail.com> |
|---|---|
| date | Wed, 03 Dec 2008 06:46:45 +0000 |
| parents | 30485bc17268 |
| children | dc696deb2cf2 |
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--- a/Python/ceval.c Wed Dec 03 00:53:18 2008 +0000 +++ b/Python/ceval.c Wed Dec 03 06:46:45 2008 +0000 @@ -504,6 +504,13 @@ static enum why_code do_raise(PyObject *, PyObject *, PyObject *); static int unpack_iterable(PyObject *, int, PyObject **); +/* Records whether tracing is on for any thread. Counts the number of + threads for which tstate->c_tracefunc is non-NULL, so if the value + is 0, we know we don't have to check this thread's c_tracefunc. + This speeds up the if statement in PyEval_EvalFrameEx() after + fast_next_opcode*/ +static int _Py_TracingPossible = 0; + /* for manipulating the thread switch and periodic "stuff" - used to be per thread, now just a pair o' globals */ int _Py_CheckInterval = 100; @@ -886,7 +893,8 @@ /* line-by-line tracing support */ - if (tstate->c_tracefunc != NULL && !tstate->tracing) { + if (_Py_TracingPossible && + tstate->c_tracefunc != NULL && !tstate->tracing) { /* see maybe_call_line_trace for expository comments */ f->f_stacktop = stack_pointer; @@ -3414,6 +3422,7 @@ { PyThreadState *tstate = PyThreadState_GET(); PyObject *temp = tstate->c_traceobj; + _Py_TracingPossible += (func != NULL) - (tstate->c_tracefunc != NULL); Py_XINCREF(arg); tstate->c_tracefunc = NULL; tstate->c_traceobj = NULL;