From d0a70d4bab2ba95ce1d6eae73f61f1e4cdf35941 Mon Sep 17 00:00:00 2001 From: Jeffrey Yasskin Date: Fri, 12 Dec 2008 21:25:13 +0000 Subject: [PATCH] Unblocked and merged revisions 67494 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r67494 | jeffrey.yasskin | 2008-12-02 22:46:45 -0800 (Tue, 02 Dec 2008) | 5 lines 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. ........ --- Python/ceval.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/Python/ceval.c b/Python/ceval.c index 5bac65fd0dc..bd35185c846 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -504,6 +504,13 @@ enum why_code { 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 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag) /* 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; @@ -3432,6 +3440,7 @@ PyEval_SetTrace(Py_tracefunc func, PyObject *arg) { 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;